Odogun, S - The Design of an Architectural Retrofit for On-Site Water Treatment in Apartment Buil... by jacques_23

THE DESIGN OF AN ARCHITECTURAL RETROFIT FOR ON-SITE GREYWATER TREATMENT IN APARTMENT BUILDINGS: A CASE STUDY OF ZETHUSHOF FLATS IN PRETORIA

SAMUEL OLUKAYODE ODOGUN

+ RETROFIT:/ Addition to an outdated version of an object or system already manufactured (Oxford English Dictionary, 2021)

PREFACE

“THOUSANDS HAVE LIVED WITHOUT LOVE, NOT ONE WITHOUT WATER” -W.H Auden, 1957“ THE BEST WAY TO PREDICT THE FUTURE IS TO DESIGN IT” -Buckminster Fuller, 2012-

THE DESIGN OF AN ARCHITECTURAL RETROFIT FOR ON-SITE GREYWATER TREATMENT IN APARTMENT BUILDINGS: A CASE STUDY OF ZETHUSHOF FLATS IN PRETORIA by Samuel Olukayode Odogun Submitted in partial fulfilment of the requirements for the degree. Master of Architecture in Architectural Technology at the Department of Architecture and Industrial Design in the FACULTY OF ENGINEERING AND THE BUILT ENVIRONMENT at the TSHWANE UNIVERSITY OF TECHNOLOGY Study leader: Prof. Jacques Laubscher Co-supervisor Mr Stephen Steyn Co-supervisor Mr Hendrik N van der Linde PRETORIA 2021 I hereby declare that this dissertation submitted for the Master of Architecture in Architectural Technology: Professional at the Tshwane University of Technology, is my own original work and has not previously been submitted to any other institution. All quoted texts and figures are indicated and acknowledged by a comprehensive list of references.

PREFACE Despite trends from leading international practices of on-site greywater treatment systems in buildings, greywater recycling in buildings, and its understanding seems generally low and vague among households in South Africa. This limited understanding is because most on-site greywater treatment systems in buildings are submerged below the natural ground level. The knowledge of greywater recycling in an urban context is that the water reclamation systems are operated by sewage treatment plants in a far-away geographical location. However, the practice of on-site greywater treatment systems seems to be the latest trend in water recycling in buildings. The future of on-site greywater treatment systems has to be didactic to create an awareness of greywater recycling works. It is the author’s opinion that the current system design approaches of on-site greywater treatment systems should be reviewed to adopt a suitable system design method of on-site didactic greywater treatment system for the retrofit of urban apartment buildings in Pretoria.

Address: P.O Box 0083 620, Park Street, Zethushof Flats, Arcadia, Pretoria 0083 Cell number: +27 84 90 38 147 Email address: Samuelodogun@gmail.com Published by the author in 2022

Video: scan QR code (Author, 2021)

MR. S.O Odogun

DEDICATION This book is dedicated to the Almighty God for his grace and wisdom throughout the study.

ACKNOLEDGEMENTS I wish to acknowledge the following, for their special contributions throughout the study: • • • • • •

Prof. Jacques Laubscher, for his guidance, knowledge, and support throughout the year. The success of this study would not have been possible without his expertise. Stephen Steyn, for his insight on the research topic, thorough guidance, advice, persistence, and consistent involvement through the process of the study. Hendrik van der Linde, for his co-supervision, effective advice, diligence, and knowledge throughout the study. PS Ntsane- Zethushof Flats’ manager, for her accomodation during the site visits and building investigation. Tanya Pretorius, for her editorial service. My parents, family, and friends, for their continuous support and encouragement. Thank you all for believing in me.

LIST OF ACRONYMNS AND ABBREVIATIONS AD BW EPA GW GBCSA LEED NBR OGTS PT PTA ROI RTF SANS SP ST STPs SD TT TUT UAB USGBC WW WC WHB WWRS ZF

Architectural devices Blackwater Environmental Protection Agency Greywater Greenstar Building Council South Africa Leadership in Energy and Environment Design National Building Regulation On-site greywater treatment system Primary treatment Pretoria Return on investment Retrofitting South Africa National Building Standard Sharon’s Place Secondary treatment Sewage treatment plants Systems design Tertiary treatment Tshwane University of Technology Urban apartment buildings United States Green Building Council Wastewater Water closets wash hand basins Wastewater recycling systems Zethushof Flats

SELECTED TERMS • Architectural devices – architectural elements from plumbing, electrical and structural devices. • Blackwater – wastewater from WCs. • Design thinking- cognitive, strategic, and practical processes adopted by designers to tackle design problems. • Greywater – wastewater from bathtubs, washing machines, kitchen sinks, showers, washbasins, and dishwashers. • On-site greywater treatment system – a system that recycles greywater in buildings. • Retrofit – adding to or improving an outdated version of an object already manufactured. • Sewage treatment plants – facilities that treat domestic wastewater from buildings. • Systems design – a method of programming wastewater recycling in buildings. • Systems thinking - an approach that shows how system’s constituents part interrelate and functions over time. • Wastewater recycling – the treatment of domestic wastewater for reuse. • Wastewater – the polluted form of water produced in buildings such as blackwater and greywater.

VII

TABLE OF CONTENTS PREFACE.......................................................................................................................................V DEDICATION.............................................................................................................................VI ACKNOWLEDGEMENTS........................................................................................................VI LIST OF ACRONYMNS AND ABBREVIATIONS..............................................................VII SELECTED TERMS..................................................................................................................VII LIST OF FIGURES......................................................................................................................XI LIST OF TABLES......................................................................................................................XIII ABSTRACT.................................................................................................................................XV

CHAPTER 1- INTRODUCTION AND BACKGROUND 1.1 INTRODUCTION......................................................................................................................................01 1.2 PROBLEM SETTINGS...............................................................................................................................02 1.2.1 STATEMENT OF THE MAIN PROBLEM..............................................................................02 1.2.2 SUB-PROBLEMS AND HYPOTHESES..................................................................................02 1.3 DELIMITATIONS.......................................................................................................................................03 1.4 ASSUMPTIONS..........................................................................................................................................03 1.5 OBJECTIVES...............................................................................................................................................03 1.6 AIMS.............................................................................................................................................................03 1.7 RESEARCH METHODOLOGY................................................................................................................04 1.8 PHASES OF THE RESEARCH DESIGN.................................................................................................04 1.9 IMPORTANCE AND BENEFITS OF THE STUDY...............................................................................06 1.10 CONCLUSION............................................................................................................................................06

CHAPTER 2- LITERATURE REVIEW 2.1 URBANISATION........................................................................................................................................07 2.2 SEWAGE TREATMENT PLANTS............................................................................................................07 2.2.1 WASTEWATER............................................................................................................................08 2.2.2 GREYWATER...............................................................................................................................08 2.2.3 BLACKWATER............................................................................................................................09 2.3 GREYWATER RECYCLING......................................................................................................................09 2.3.1 ARCHITECTURAL DEVICES..................................................................................................09 2.3.2 SYSTEMS DESIGN......................................................................................................................10 2.4 WASTEWATER TREATMENT SYSTEMS...............................................................................................11 2.4.1 PRIMARY TREATMENT............................................................................................................11 2.4.2 SECONDARY TREATMENT.....................................................................................................11 2.4.3 TERTIARY TREATMENT..........................................................................................................12 2.4.4 WASTEWATER RECYCLING SYSTEMS (WWRS) DESIGN IN BUILDINGS................12 2.5 ON-SITE TREATMENT SYSTEMS.........................................................................................................14 2.6 LOCAL AND INTERNATIONAL ON-SITE GREYWATER TREATMENT SYSTEMS..................15 2.6.1 UNITED STATES OF AMERICA - BIOMICROBICS...........................................................15 2.6.2 TAIWAN - AQUA2USE..............................................................................................................16 2.6.3 SOUTH AFRICA - AQUA AERO VITAE................................................................................17 2.6.4 SOUTH AFRICA - BIOROCK..................................................................................................17 2.7 BEST PRACTICES SUMMARY.................................................................................................................18 2.8 RETROFITTING BUILDINGS..................................................................................................................19 2.9 CASE STUDIES...........................................................................................................................................20 2.9.1 RETROFIT CASE STUDY 1: ZETHUSHOF FLATS BUILDING, PRETORIA.................20 2.9.2 BUILT-TO-PURPOSE CASE STUDY 2: SHARON’S PLACE, PRETORIA........................21 2.10 CONCLUSION............................................................................................................................................22

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CHAPTER 3- SYSTEM DESIGN DEVELOPMENT 3.1 INTRODUCTION..................................................................................................................................23 3.2 DESIGN DEVELOPMENT...................................................................................................................23 3.3 SPECIFIC TREATMENT OF THE MAIN PROBLEM AND SUB-PROBLEMS (3 AND 4)......23 3.3.1 SUB-PROBLEM 3...................................................................................................................33 3.3.2 SUB-PROBLEM 4...................................................................................................................33 3.4 PHASE 2.1: BACKGROUND................................................................................................................24 3.4.1 ZETHUSHOF FLATS’ WASTEWATER SYSTEM FOR A RETROFIT ..........................25 3.4.3 EXISTING ZETHUSHOF FLATS’ WASTEWATER SYSTEM.........................................26 3.4.4 COMPARISON BETWEEN SHARON’S PLACE AND ZETHUSHOF FLATS’ WASTEWATER SYSTEM......................................................................................................27 3.4.5 PROPOSED SYSTEM DESIGN............................................................................................28 3.5 PHASE 2.2: DESIGN DEVELOPMENT..............................................................................................31 3.5.1 OGTS CAPACITY..................................................................................................................31 3.5.2 ZETHUSHOF FLATS’ GREYWATER CALCULATION..................................................32 3.5.3 ASSUMPTIONS......................................................................................................................32 3.5.4 DEFINING THE SHAPE OF EACH TANK THROUGH SKETCH...............................34 3.6 TANK ASSEMBLY OF THE DESIGNED OGTS OF THE TREATMENT PHASE....................37 3.7 VIEWS OF THE DESIGNED OGTS OF THE TREATMENT PHASE.........................................38 3.8 MATERIAL SPECIFICATION FOR EACH PIPE IN THE DESIGNED OGTS............................39 3.8.1 GALVANISED STEEL PIPE..................................................................................................39 3.8.2 DUCTILE (DI) IRON PIPE...................................................................................................39 3.8.3 PLASTIC PIPES- UNPLASTICIZED POLYVINYL CHLORIDE (UPVC) AND POLYVINYL CHLORIDE (PVC)........................................................................................39 3.8.4 SELECTED MATERIAL: DUCTILE IRON........................................................................40 3.9 MATERIAL SPECIFICATION OF THE TANKS..............................................................................41 3.9.1 UNPLASTICISED POLYVINYL CHLORIDE (UPVC)...................................................41 3.9.2 POLYETHYLENE TEREPHTHALATE (PET)..................................................................41 3.9.3 HIGH-DENSITY POLYETHYLENE (HDPE)...................................................................41 3.9.4 SELECTED MATERIAL: PET AND HDPE.......................................................................42 3.10 FULL DESCRIPTION OF THE DESIGNED OGTS OF THE TREATMENT PHASE................42 3.11 FILTER SPECIFICATION OF THE DESIGNED OGTS- MAIN TREATMENT PHASE.....................................................................................................................................................43 3.12 CROSS-SECTION PERSPECTIVE OF THE DESIGNED OGTS...................................................43 3.13 FLOW DIAGRAM OF THE DESIGNED OGTS OF THE TREATMENT PHASE.....................44 3.14 EXPLODED VIEW OF THE DESIGNED OGTS OF THE TREATMENT PHASE....................45 3.15 FULL PROTOTYPE AND LAYOUT OF THE DESIGNED OGTS FOR APARTMENT BUILDINGS.................................................................................................................45 3.16 COMPARISON BETWEEN THE DESIGNED OGTS AND THE SELECTED BEST PRACTICES OF OGTS.........................................................................................................................46 3.17 FINDINGS..............................................................................................................................................47 3.18 CONCLUSION.......................................................................................................................................47

CHAPTER 4- SYSTEM APPLICATION 4.1 INTRODUCTION.......................................................................................................................................48 4.2 REVIEW OF THE RESEARCH DESIGN.................................................................................................48 4.3 MOUNTING DETAILS OF THE FIXED COMPONENTS OF THE DESIGNED OGTS................49 4.3.1 SKELETAL STRUCTURES HOLDING THE DESIGNED OGTS IN PLACE TO ZETHUSHOF FLATS’ FACADE...........................................................................50 4.3.2 DESIGNED OGTS MOUNTED ONTO ZF’ FAÇADE...........................................................50 4.4 THE DESIGNED OGTS MOUNTED TO ZETHUSHOF FLATS’ FACADE......................................53 4.7 COMPONENTS OF THE DESIGNED OGTS........................................................................................54 4.8 SPECIFICATION OF THE OGTS ADDITION......................................................................................55 4.9 DIVISION OF THE DESIGNED OGTS TO ZETHUSHOF FLATS’ FLOOR PLAN AND FACADE........................................................................................................................................................56 4.10 ZETHUSHOF FLATS’ FAÇADE DEVELOPMENT- A RETROFIT.....................................................59 4.10.1 AUTONOMOUS MOVEMENT OF THE OGTS’ RECYCLING TANK ONTO ZETHUSHOF FLATS’ FAÇADE..................................................................................................60 4.11 SYSTEM ILLUSTRATION ON THE SELECTED CASE STUDIES OF URBAN APARTMENT BUILDINGS IN PRETORIA.......................................................................................................................61 4.12 FINDINGS....................................................................................................................................................61 4.13 CONCLUSION.............................................................................................................................................61

CHAPTER 5- FINDINGS, RECOMMENDATIONS, AND CONCLUSION 5.1 5.2 5.3

SUMMARY OF THE RESEARCH.............................................................................................................62 RESEARCH HYPOTHESES / RESEARCH FINDINGS........................................................................63 RESEARCH RECOMMENMDATIONS..................................................................................................63

5.4 5.5

FUTURE RESEARCH................................................................................................................................64 RESEARCH CONCLUSION......................................................................................................................64

REFERENCES....................................................................................................................................................65

LIST OF FIGURES Figure 1: Water systems (Nyengineers, 2021).......................................................................................................01 Figure 2: The process of a municipal sewage treatment plant (Temboo, 2019: 1)............................................07 Figure 3: Breakdown of wastewater from buildings (Amoatey & Bani, 2016: 380).........................................08 Figure 4: Pipe network of architectural devices (Fane & Reardon, 2008: 37) as cited by (Smith & Stasinopoulos, 2010)...............................................................................................................................09 Figure 5: Definition sketch showing various forms of satellite wastewater systems: (a) commercial building interception type (b) extraction type (c) upstream type (d) individual home with greywater interception type (Leverenz & Tchobanoglous, 2012: 5595).....................................................................................................10 Figure 6: Primary treatment operation diagram (EPA, 1998: 3)........................................................................11 Figure 7: Secondary treatment operation (EPA, 1998: 4)....................................................................................11 Figure 8: Wastewater recycling system in a storey building (Raček, 2020: 1)...................................................12 Figure 9: AgriNesture building wastewater recycling system (H & P Architects, 2018: 38)...........................13 Figure 10: Optimal energy-water management in urban residential buildings through greywater recycling in sustainable cities and society (Wanjiru & Xia, 2017: 655)..............................................................................13 Figure 11: Typical view of a water supply point in an informal settlement (Carden et al., 2008: 3)..............14 Figure 12: Pit privy, wastewater treatment using a septic tank (WEDC, 2002: 105; Harvey et al., 2002)................................................................................................................14 Figure 13: Conventional OWTS (NSFC, 2000) & Gilbert Gedeon, Port Elizabeth.........................................15 Figure 14: Biomicrobics on-site greywater treatment system. Country: USA (Biomicrobics, 2021)............16 Figure 15: Aqua2use domestic greywater treatment system. Country: Taiwan (Aqua2use, 2021)................16 Figure 16: Aqualoop greywater treatment system. Country: South Africa (Aqua Aero Vitae, 2021)...........17 Figure 17: Biorock greywater treatment system. Country: South Africa (Biorock, 2021)..............................17 Figure 18: Retrofit of a building structure (CiviConcepts, 2021).......................................................................19 Figure 19: Zethushof Flats, Pretoria southern view (Author, 2021)..................................................................20 Figure 20: Sharon’s Place western view (Armourelite, 2021)..............................................................................21 Figure 21: Sharon’s Place secluded floor for the hot water supply system (IBSM, 2014)................................21 Figure 22: Zethushof Flats fifth-floor plan indicating the wastewater duct point (Figure 24 or Section x-x) drawn to scale 1:100 (Author, 2021) adapted from TUT architecture department resource.........................25 Figure 23: Zethushof Flats’ wastewater system drawn from Section x-x in Figure 23 on scale 1:100 (Author, 2021)...........................................................................................................................................................26 Figure 24: Zethushof Flats’ wastewater system (Author, 2021)..........................................................................27 Figure 25: Effects of the Zethushof Flats’ wastewater system (Author, 2021)..................................................27 Figure 26: Sharon’s Place wastewater system (IBSM, 2014)................................................................................27 Figure 27: Zethushof Flats’ wastewater system (Author, 2021)..........................................................................27 Figure 28: First conceptual 2D sketch on elevation view to be mounted onto the Zethushof Flats’ facade (Author, 2021)...........................................................................................................................................................28 Figure 29: First conceptual 2D sketch (in motion). Elevation view to be mounted onto the Zethushof Flats’ facade (Author, 2021)...............................................................................................................................................29 Figure 30: 2D view of the finalised conceptual sketch (Author, 2021)..............................................................29 Figure 31: 2D view of the proposed system schematic diagram on scale 1:100 (Author, 2021)....................30 Figure 32: Water use for a family of four in South Africa (Water Wise, 2021).................................................32 Figure 33: Sketch proposal of the designed OGTS- not to scale........................................................................34 Figure 34: Preliminary treatment tank dimension. Isometric and elevation views are drawn to scale 1:100 (Author, 2021)...........................................................................................................................................................35 Figure 35: Main treatment tank dimension. Isometric and elevation views are drawn to scale 1:100 (Author, 2021)...........................................................................................................................................................35 Figure 36: First storage tank dimension. Isometric and elevation views are drawn to scale 1:100 (Author, 2021)...........................................................................................................................................................35 Figure 37: Recycling tank dimension. The isometric and elevation views are drawn to scale 1:100 (Author, 2021)...........................................................................................................................................................36 Figure 38: Second storage tank dimension. The isometric and elevation views are to scale 1:100 (Author, 2021)...........................................................................................................................................................36 Figure 39: Greywater storage tank dimension- Isometric & elevation views- drawn to scale 1:100 (Author, 2021)...........................................................................................................................................................36 Figure 40: Tank assembly front and isometric view are drawn to scale 1:100 (Author, 2021) .......................37 Figure 41: Air vent cover for the designed system. Front and isometric views are drawn to scale 1:100 (Author, 2021)...........................................................................................................................................................37 Figure 42: Top view (left) and bottom view (right) of the treatment phase are drawn to scale 1:100 (Author, 2021)...........................................................................................................................................................38

Figure 43: Elevation view. Front, rear, right, and left of the treatment phase are drawn to scale 1:100 (Author, 2021).....................................................................................................................................................................38 Figure 44: Isometric view. Left, right, and rear of the treatment phase is drawn to scale 1:100 (Author, 2021)....38 Figure 45: Left, right, and rear of the fish-eye view of the treatment phase are drawn to scale 1:100 (Author, 2021).....................................................................................................................................................................39 Figure 46: Pipe specification of the designed system on an isometric view drawn to scale 1:100 (Author, 2021).....................................................................................................................................................................40 Figure 47: Pipe specification of the designed system. Final storage tank isometric view arise drawn to scale 1:100 (Author, 2021).....................................................................................................................................................................41 Figure 48: Full description of the designed system of the treatment phase on isometric view on scale 1:100 (Author, 2021).....................................................................................................................................................................42 Figure 49: Cross-section of the designed OGTS of the treatment phase is drawn to scale 1:100 (Author, 2021).....................................................................................................................................................................43 Figure 50: Flow diagram of the designed OGTS of the treatment phase is drawn to scale 1:100 (Author, 2021).....................................................................................................................................................................44 Figure 51: Exploded view of the designed OGTS of the treatment phase on scale 1:100 (Author, 2021)..............45 Figure 52: Front view of the full unit of the designed OGTS-scale 1:100 (Author, 2021)........................................45 Figure 53: Isometric view of the full unit of the designed OGTS-scale 1:100 (Author, 2021) .................................46 Figure 54: Preliminary treatment tank. Isometric view front and rear are drawn to scale 1:100 (Author, 2021).....................................................................................................................................................................49 Figure 55: Main treatment tank. Isometric views of the front and rear are drawn to scale 1:100 (Author, 2021).....................................................................................................................................................................49 Figure 56: First storage tank. Isometric views of the front and rear are drawn to scale 1:100 (Author, 2021).......49 Figure 57: Assembled OGTS of the treatment phase (rear, rear- isometric fisheye view) drawn to scale 1:100 (Author, 2021).....................................................................................................................................................................50 Figure 58: Skeletal structural element. Elevation view is drawn to scale 1:10 (Author, 2021) .................................50 Figure 59: Mounting skeletal structure of the treatment phase to a wall. The left fisheye view is drawn to scale 1:100 (Author, 2021)...........................................................................................................................................................50 Figure 60: Second storage tank. Elevation view is drawn to scale 1:100 (Author, 2021)...........................................51 Figure 61: Mounting skeletal structure of the second storage tank (left fisheye view)to scale 1:100 (Author, 2021).....................................................................................................................................................................52 Figure 62: The designed OGTS of the treatment phase and second storage tank mounted onto a wall facade (fisheye and front view) to scale 1:100 (Author, 2021)..................................................................................................52 Figure 63: Front view of the full unit of the designed OGTS to scale 1:100 (Author, 2021)....................................53 Figure 64: Isometric view of the full unit of the designed OGTS to scale 1:100 (Author, 2021).............................53 Figure 65: Components of the designed OGTS on isometric view- scale 1:100 (Author, 2021).............................54 Figure 66: The division of the designed OGTS on the Zethushof Flats fifth-floor plan to scale 1:100 (Author, 2021).....................................................................................................................................................................57 Figure 67: First section of the system treatment on the Zethushof Flats fifth-floor plan and isometric view to scale 1:100 (Author, 2021).................................................................................................................................................58 Figure 68: Second section of the system treatment on the Zethushof Flats fifth-floor plan and isometric view to scale 1:100 (Author, 2021).................................................................................................................................................58 Figure 69: Third section of the system treatment on the Zethushof Flats fifth-floor plan and isometric view to scale 1:100 (Author, 2021).................................................................................................................................................59 Figure 70: The designed OGTS mounted onto the Zethushof Flats’ facade in divisions to scale 1:100, perspective view (Author, 2021)............................................................................................................................................................59 Figure 71: Rendered view of the designed system onto Zethushof Flats’ façade to scale 1:100, perspective view (Author, 2021).....................................................................................................................................................................60 Figure 72: Autonomous movement of the designed system’s recycling tank’s elevation view to scale 1:100 (Author, 2021)............................................................................................................................................................................60 Figure 73: Designed OGTS mounted onto the Sharon’s Place eastern facade (Author, 2021).................................61 Figure 74: Designed OGTS mounted on the Zethushof Flats southern facade (Author, 2021)...............................61

XII XI

LIST OF TABLES Table 1: The sub-problems and their associated hypotheses................................................................................03 Table 2: Research design outline (compiled by author)........................................................................................05 Table 3: Selected best practices of OGTS...............................................................................................................16 Table 4: The features of a biomicrobics system......................................................................................................16 Table 5: The features of Aqua2use system...............................................................................................................17 Table 6: The features of Aqualoop system...............................................................................................................18 Table 7: Features of the Biorock system..................................................................................................................18 Table 8: Summary of features from the selected international and local best practices of OGTS..................19 Table 9: Research objectives (Chapter 1)...............................................................................................................23 Table 10: Sub-problems 3 and 4..............................................................................................................................23 Table 11: Summary of the research design, Phase 2.1 (compiled by the author)..............................................24 Table 12: Summary of the research design, Phase 2.2 (compiled by the author)..............................................31 Table 13: Occupancy or building classification – SANS 10400-XA: 2011 (redrawn by the author)..............31 Table 14: Design population, SANS 10400-XA: 2011 (redrawn by the author)................................................31 Table 15: Greywater calculation (Water Wise) (Figure 33).................................................................................33 Table 16: Entire tank capacity in relation to its dimension (Figure 32 to 36)...................................................33 Table 17: Summary of the designed tanks’ capacity (litres).................................................................................34 Table 18: Comparison between UPVC and PVC material...................................................................................40 Table 19: Comparison between PVC, PET, and HDPE material.........................................................................41 Table 20: Comparison between sand filters and cartridge filters.........................................................................43 Table 21: Comparison between the designed OGTS and selected best practices of OGTS............................46 Table 22: Research objectives from Chapter 1.......................................................................................................47 Table 23: Review of research objective 1.8.5 from Chapter 1..............................................................................48 Table 24: Review of sub-problem 4.........................................................................................................................48 Table 25: Summary of the research design, Phase 3 (compiled by author)........................................................48 Table 26: The specification of the system addition................................................................................................55 Table 27: Review of the research objectives from Chapter 1 (compiled by the author)...................................62 Table 28: Review of the research hypotheses versus the research findings (compiled by the author)...........63

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ABSTRACT The purpose of this study is to determine an applicable system design for on-site greywater recycling and management in urban apartment buildings. This study is of higher significance to engineers and serve as a design blueprint for modelling the designed on-site greywater treatment system to apartment buildings in Pretoria. According to research, urbanisation and the increasing population growth in South Africa are major factors putting pressure on the operational load of sewage treatment plants- causing them to malfunction. Access to safe drinking water and basic sanitation in urban buildings in South Africa is an essential part of the Sustainable Development Goals (SDGs) for the 2030 Agenda. The author questions the use of fresh potable water for flushing WCs. This could be used to supplement other important water needs in urban buildings. This study explores greywater recycling and reuse for flushing WCs in apartment buildings. Sewage treatment plants can then treat blackwater effectively, improve city-wide water quality, and lessen or eliminate contaminants reaching nearby water bodies. The methodology of the study involved the investigation of the existing wastewater system in Zethushof Flats, Pretoria, South Africa. An on-site greywater treatment system was designed for flushing WCs. Design practices were used to limit, develop, and further the investigation. Design and systems thinking methodologies were also applied. The study concludes that the adoption of the designed on-site greywater treatment system onto apartment buildings’ facades enhances occupants’ interaction with the designed system and creates awareness of on-site greywater treatment works and water usage. Keywords: Greywater recycling, on-site greywater treatment system, retrofit, system design, urban apartment buildings, wastewater.

CHAPTER 1 1.1 INTRODUCTION

Figure 1: Water systems (Nyengineers, 2021)

The distribution network of water systems in buildings typically resembles the circulatory system of the human body. The appearance (supply) and disappearance (exit) of water in buildings seems vague and its exposure would be didactic if visible. Water systems in buildings are known to be hidden mostly in ducts or building’s structural elements. Buildings are built for human beings. However, most building systems are not didactic to its users.

The future of water systems is envisaged to be didactic and visible so that building occupants experience and interact with water systems in buildings, such as the interactive view of rivers. The author considers this concept to be biophilic. This biophilic approach could enhance the ratio of greywater recycling to water consumption among building households. A sustainable building is one efficient to meet the users’ demand for water and energy; however, rapid urbanisation and population growth in urban centres and cities are factors that have put much pressure on the limited resources supplied to urban buildings (Neyestani, 2017: 5). From a study by Mitchell, Blignaut, & Crookes, (2014: 48), the author deduces that increasing level of urbanisation in South Africa’s Gauteng province has intensified the need for water in urban buildings. Urbanisation has thus also intensified the demand for alternative wastewater treatment systems, due to the operational load pressure of the municipal sewage treatment plants (Mitchell, de Wit, Blignaut, & Crookes, 2014: 48). South Africa is a semi-arid country with a surface area of roughly 1,219 million square kilometres. Constantine, Musingafi, & Tom, (2014: 72), states that South Africa’s water resources are scarce and severely limited because of its low annual rainfall, leading to occasional drought in some parts of the country (Constantine, Musingafi, & Tom, 2014: 72). The country’s average annual rainfall (450mm) is well below the world’s average around 860mm (Basson, 2011: 1). The country’s rapid urbanisation has resulted in the deterioration of water quality in urban streams and lakes because of the imbalance between the demand and supply of water (Constantine, Musingafi, & Tom, 2014: 72). Studies acknowledge that South Africa’s urban sewage treatment infrastructure is in poor condition, leading to the country’s myriad pollution issues (Herbig, 2019: 1). In the Green Drop Report by the Water Affairs, South Africa, Minister Buyelwa Sonjica, also notes that “the bulk of the plants can be described as poor to non-functional” (Hegley, 2010: 14-15). Estimates suggest that from 449 of the 852 wastewater treatment plants evaluated in South Africa, only 203 scored “better than 50% in measurement against the stringent criteria set” (Hegley, 2010: 14-15). The author hypothesises that the current state of most sewage treatment plants in South Africa is due to the bulk loads of treating wastewater (blackwater and greywater) from urban buildings that have increased the concentration of water contaminants to waterbodies nearby. The Green Drop Report concludes with a demand for an investigation into alternative means of wastewater treatment to reduce the operational load of sewage treatment plants in Pretoria (Hegley, 2010). There are various studies regarding on-site greywater treatment systems, and this study suggests and elaborates on the data collected in those studies through a design project.

1.2 PROBLEM SETTINGS Water is a scarce commodity in South Africa. There are other significant needs for water in urban buildings, such as bathing and flushing WCs. The current COVID-19 pandemic raises the need for water for hand washing. It is advisable not to waste water, specifically greywater. The level of urbanisation and rapid population growth has increased the need for potable water. The urbanisation of South Africa’s Gauteng Province has put pressure on the operation of most of the province’s sewage treatment plants, causing them to malfunction (Mitchell et al., 2014: 3). Research also notes that the ratio of wastewater recycling to water consumption in urban buildings is generally low in South Africa (Binnie & Kimber, 2008: 6 & 11). Greywater recycling should be widely adopted to urban buildings (Kvarnström, 2005: 7). 1.2.1 STATEMENT OF THE MAIN PROBLEM The main problem statement is set as “what alternative approach should be adopted to enhance on-site greywater recycling and management in urban apartment buildings?” 1.2.2 SUB-PROBLEMS AND HYPOTHESES Table 1: Sub-problems and their associated hypotheses- (compiled by the author) SUB-PROBLEMS 1-4

HYPOTHESES

-Sub-problem 1What are the specific wastewater systems in urban apartment buildings in Pretoria?

-Hypothesis 1It is hypothesised that the wastewater systems in urban apartment buildings in Pretoria are largely similar- wastewater from urban buildings channelled to the sewage plants for treatment.

-Sub-problem 2How could the sewage treatment plant in Pretoria reduce operational load pressure?

-Hypothesis 2It is hypothesised that the sewage treatment plants in Pretoria would have reduced operational load pressure if the wastewater treatment load were reduced.

-Sub-problem 3How could the sewage treatment plant in Pretoria achieve a reduced treatment load of wastewater?

-Sub-problem 4What could enhance wastewater recycling in urban apartment buildings in Pretoria?

-Hypothesis 4It is hypothesised that wastewater recycling in urban apartment buildings in Pretoria would be enhanced if an appropriate system is designed to adopt on-site treatment system.

1.3 DELIMITATIONS This study is limited to the following: • • • • •

This study focuses on urban apartment buildings in Pretoria, applying the case study of ZF, Pretoria, to represent a typical urban apartment building. This study does not intervene in the building structure of ZF, Pretoria, or other urban apartment buildings. This study excludes the treatment of water for potable use. Though rainwater harvesting may contribute to sustainability, it does not reduce the operational load of sewage treatment plants. Therefore, this consideration is excluded as a focus of the study. This study excludes the recycling of blackwater.

1.4 ASSUMPTIONS The study is performed under the following assumptions: • • •

The pipe and tank material properties as identified via research are accurate. The data sourced from Waterwise are accurate. The data sourced from the selected international and local best practices of on-site greywater treatment systems are accurate.

1.5 OBJECTIVES Consequently, the specific sub-objectives of this study are: • To explore specific wastewater systems in urban apartment buildings from both international and local case studies. • To investigate the wastewater system in ZF through site visits and architectural drawing review. • To compare the wastewater system in ZF with international and local best-practice case studies. • To design an on-site treatment system design that recycles greywater in urban apartment buildings using ZF through selected data from the literature review. • To design an on-site greywater treatment system design blueprint that could be adapted to diverse urban apartment buildings in Pretoria. 1.6 AIMS The specific aims are as follows: Firstly, • to define the importance of an architectural retrofit to existing urban apartment buildings in Pretoria, • to identify specific concepts of retrofitting buildings, • to identify the need for retrofitting the ZF wastewater system, • to identify specific wastewater systems that have been used in urban apartment buildings. Secondly, • to emphasise the effects of urbanisation on the operational load of sewage treatment plants, • to identify and define the sewage treatment plants’ process of collecting, treating, and recycling wastewater from urban buildings. 03

Thirdly, • to briefly note the importance of on-site greywater treatment systems in urban apartment buildings, • to explore international best practices of on-site greywater treatment systems to inform the system to be designed, • to explore local best practices of on-site greywater treatment systems to inform the system to be designed. 1.7

RESEARCH METHODOLOGY

The methodology of this study involves the investigation, development, and proposal of a modified wastewater system in ZF, Pretoria. Comparative studies of international, local, and ZF’ wastewater systems were carried out for the author to make recommendations for a unique system design method for apartment buildings. A design research methodology was explored where architectural design practices were used to limit, develop, and further the investigation. Design thinking and systems thinking were other methodologies explored. The following methods were used to gather data: • Archival research • Desk review • Design research. 1.8

PHASES OF THE RESEARCH DESIGN

The research design is framed in a particular environment. Studies emphasise the effects of urbanisation and overpopulation to the built environment in cities and this inspired the author to take the course of the research.

Table 2 outlines the research design as compiled by the author Table 2:

Research design outline (compiled by the author)

PHASE 1.1:

CHAPTER 2

Theme: Architectural retrofit Focus area: Background study on key literatures Data source: Selected literature (articles, books, electronic media) 1.1.1 Define the problem settings and the importance of retrofitting urban buildings 1.1.2 Define wastewater and its classification 1.1.3 Identify the need to retrofit the ZF wastewater system. 1.1.4 Identify the specific techniques of retrofitting buildings

PHASE 1.2:

CHAPTER 2

Theme: Wastewater recycling Focus area: Identifying specific process of wastewater recycling Data source: Selected literature (articles, books, electronic media) 1.2.1 Identify specific wastewater systems in urban apartment buildings. 1.2.2 Identify the challenges faced by the sewage treatment plants in South Africa 1.2.3 Identify specific wastewater treatment processes by sewage treatment plants.

PHASE 1.3:

CHAPTER 2

Theme: On-site greywater recycling Focus area: Best practices of an on-site greywater recycling system Data source: Selected literature (articles, books, electronic media) 1.3.1 Note the importance of an on-site treatment system in urban apartment buildings 1.3.2 Explore two international best practices of on-site greywater treatment systems outside the African continent 1.3.3 Explore two local best practices of on-site greywater treatment systems in South Africa.

PHASE 2: SYSTEM DESIGN DEVELOPMENT PHASE 2.1 (Chapter 3) Theme On-site greywater recycling system (OGTS) design Focus area: Case study investigation, conceptual sketches, and system designing Data source: Electronic media, paper sketches, Architectural drawing, and modelling on Autodesk Revit2.1.1 To investigate the existing wastewater system in the ZF building through site visits and architectural drawings review 2.1.2 To identify the features of the selected international and local best practice of OGTS to inform the conceptual sketches and the design of an alternative OGTS 2.1.3 To finalise the conceptual sketches of the OGTS.

PHASE 3:

SYSTEM APPLICATION

Theme:

On-site greywater recycling system (OGTS) installation

Focus area:

Installation details of the designed system to ZF building

Data source:

Architectural drawings

3.1 3.2

To design the mounting skeletal structure holding the designed OGTS on to ZF’s façade To explore the approach of splitting the designed OGTS to the ZF building.

PHASE 2.2 Theme Focus area:

Data source: 2.2.1 2.2.2 2.2.3 2.2.4

(Refer to Chapter 3) On-site greywater recycling system capacity Defining the proposed system capacity using the ZF building as a casestudy Greywater calculation and electronic media

PHASE 4:

FINDINGS (Chapter 5)

Recommendations and conclusions

To analyse the occupancy and population of each apartment unit in the ZF building in accordance with SANS 10400 -XA To calculate ZF’ s greywater generated daily and weekly per household To explore the volume of the designed system for the ZF case study To model the finalised conceptual sketch of the system in AUTODESK Revit- .

1.9 IMPORTANCE AND BENEFITS OF THE STUDY The results of this project will serve as a design blueprint when adopting an on-site greywater treatment system for the retrofit of urban apartment buildings in Pretoria. On-site greywater treatment systems mounted onto apartment buildings in Pretoria: • • • • •

Reduces the cost of buying municipal water for flushing of WCs in buildings. Leads to a reduced cost of sewage services. Reduces the demand for potable water to flush WCs. Enhances students’ understanding of greywater treatment works in the specific instance of ZF, a Tshwane University of Technology residence. Aids efficient water consumption in water-scarce South Africa.

1.10 CONCLUSION Chapter 1 introduces the research context and problem settings. The main problem statement, sub-problems, and related hypotheses were defined. The research design was also defined to inform the research structure. The objectives, aims, delimitations, assumptions, methodology, importance, and benefits of this study were listed.

CHAPTER 2- LITERATURE REVIEW 2.1 URBANISATION The level of population growth and urbanisation in cities has led to the trends of buildings that are designed and constructed today such as apartment buildings (Aoyi, et al., 2014). The evolution of buildings from ancient times to the present depicts the essence of retrofitting buildings where new building technologies are added to existing buildings for efficient building performance. Urbanisation and overpopulation are issues that affect urban centres globally, and its effect on air and water quality in specific locations are recurring areas of concern (Duh et al., 2008). 2.2 SEWAGE TREATMENT PLANTS South Africa’s sewage treatment plants (STPs) have been declared a national disaster (Begg, 2021). Sewage treatment plants treat pollutants from domestic and municipal wastewater (Hreiz et al., 2015: 901). A sewage treatment plant is categorised into three phases: primary (solid removal), secondary (bacterial decomposition), and tertiary (extra filtration), each incorporating physical, chemical, and biological treatment methods to effectively remove contaminants (Hreiz et al., 2015: 901). Drainage networks are essential for transporting wastewater from residential buildings to sewage treatment plants, however, the installation and maintenance of drainage networks and extensive piping are costly (Mitchell et al., 2014: 3). The transporting distance for treated water from sewage treatment plants to urban buildings and pipe leakages are factors that lead to the loss of water revenue. These factors inspired the author to design a unique on-site greywater treatment system (OGTS) for urban apartment buildings in Pretoria. Figure 2 illustrates a sample of sewage network between buildings, municipal wastewater collection point, and sewage treatment plant.

Figure 2: The process of a municipal sewage treatment plant (Temboo, 2019: 1)

The hotspot lengend in figure 2 indicates the main treatment phases/ points of sewage treatment plants.

2.2.1 WASTEWATER Wastewater is the polluted water produced from the average human activity in buildings (Owa, 2013: 65). According to the United Nations (UN) Water Quality and Sanitation Programme, almost 80% of global wastewater is pumped into the ecosystem without proper treatment, resulting in almost 1.8 billion people utilising faeces-contaminated water (Roman & Brennan, 2021: 1; WHO/ UNICEF, 2015: 1). The UN study emphasises the global effect of the operational load pressure on sewage treatment plants resulting in poor water quality produced and utilised by the ecosystem. The level of urbanisation and rapid population growth in a specific region could reduce the efficient treatment of wastewater from sewage treatment plants, increasing the concentration of water contaminants in water bodies (Musingafi, 2014). South Africa’s Gauteng province has the highest population density in the country, with large-scale industrial and domestic activities that produce large volumes of wastewater (Aoyi, et al., 2014: 18). According to Statista, in 2020, over 67.35% of South Africa’s population lived in urban areas and cities, with that number expected to rise to 71% by 2030, increasing the demand for essential services such as water (Statista, 2020). Greywater recycling in buildings is essential to reduce the concentration of water contaminants in water bodies in the country and via rivers to neighbouring countries. Greywater recycling will also reduce the tapping of natural water resources (Asano et al., 2007: 41). The classification of wastewater in buildings is illustrated in figure 3.

Figure 3: Breakdown of wastewater from buildings (Amoatey & Bani, 2016: 380) 2.2.2 GREYWATER Greywater is the wastewater generated in residential buildings from architectural devices such as bath tubs, washing machines, sinks, showers, dishwashers, and other kitchen appliances, but not from WCs (Stec et al., 2017: 194). The specific contaminants of greywater are soap, and food particles. Greywater accounts for 75% of overall household water use in South Africa (Oteng-Peprah et al., 2018: 2).

2.2.3 BLACKWATER Blackwater is the wastewater generated in buildings from flush WCs, containing urine, water, faeces, and toilet paper. The water used to flush a WC is between five to nine litres (Gao, et al, 2019: 249). There are several studies on efficient WC that reduce the number of litres of water used for flushing. Examples of specific alternative WC technology are the waterless WC by the Bill & Melinda Gates Medical Research Institute, low-flow WC, compositing WC, incinerating WC, dry-flush WC and nano-membrane WC). The reality is that flushing a WC requires plenty of water. This study focuses on recycling greywater for flushing WCs. 2.3 GREYWATER RECYCLING Greywater recycling is the treatment of domestic greywater for reuse, such as irrigation and flushing (Melin, et al., 2006: 276). There are other factors of greywater treatment, which are the reduction of biodegradable organic substances in the environment, the elimination of pathogens, and the reduction of nutrient concentration in water (Amoatey & Bani, 2016: 379). As compared to the overall water consumption in South Africa’ buildings, greywater recycling is generally low (Swilling, & Annecke, 2006: 322). Greywater recycling is essential for a water-scarce region such as South Africa (Kamizoulis, et al., 2003: 5). 2.3.1 ARCHITECTURAL DEVICES Architectural devices are systems of various building elements connected to perform a unique function that is not performable by a building element alone (Grady, 2020: 3). A specific example is the pipe network of showers, wash hand basins, kitchen sinks, WCs, and bathtubs. These architectural devices drain volumes of wastewater after use to the sewage treatment plants, increasing the concentration of water contaminants for treatment by sewage treatment plants. Figure 4 illustrates an example of the connection between architectural devices in buildings.

Figure 4: Pipe network of architectural devices (Fane & Reardon, 2008: 37) as cited by (Smith & Stasinopoulos, 2010)

2.3.2 SYSTEMS DESIGN Wastewater systems design in urban buildings are distinctive structure of discharging wastewater from architectural devices to treatment locations (Grady, 2020: 3). A study by Tchobanoglous and Leverenz (2012) proposes hybrid wastewater systems using satellite facilities in urban areas to treat and recycle greywater for reuse in urban buildings (Figure 5). The author considers this wastewater system design costly to implement in urban apartment buildings, and therefore the retrofit has to be subsidised.

(d) Illustrates building’s greywater system on section

(b) Illustrates satellite reclamation plant on site diagram

(a) Illustrates building’s greywater system on section

Figure 5: Definition sketch showing various forms of satellite wastewater systems: (a) commercial building interception type (b) extraction type (c)upstream type (d) individual home with greywater interception type (Leverenz & Tchobanoglous, 2012: 5595)

2.4 WASTEWATER TREATMENT SYSTEMS Wastewater treatment is a practice that requires physical, chemical, and biological unit operations due to the nature of contaminants in wastewater (Amoatey & Bani, 2011: 382). The level of treated wastewater is dependent on the quality required, using various treatment technologies (Mekala et al., 2008: 2). According to the United States of America’s Environmental Protection Agency (EPA) (1998: 1-6), wastewater treatment occurs in three levels: primary treatment, secondary treatment, and tertiary treatment. These are the basic processes of wastewater treatment techniques adopted by most sewage treatment plants and on-site greywater treatment systems in buildings. 2.4.1 PRIMARY TREATMENT The primary treatment is preceded by a preliminary treatment that removes solid suspension by screening and grit chambers to maintain other treatment units (Mekala et al., 2008: 3). The primary treatment removes organic and inorganic solids by sedimentation and skimming floating scum materials, producing primary effluent (Amoatey & Bani, 2016; EPA, 1998). Figure 6 illustrates a typical primary treatment operation diagram.

Figure 6: Primary treatment operation diagram (EPA, 1998: 3)

2.4.2 SECONDARY TREATMENT The primary effluent later flows into the secondary treatment phase to remove residual organics by trickling through a filter and producing secondary effluent (EPA, 1998: 4). Figure 7 illustrates a typical secondary treatment operation.

Figure 7: Secondary treatment operation diagram (EPA, 1998: 4)

2.4.3 TERTIARY TREATMENT The tertiary treatment is an advanced stage of treating wastewater, where secondary treatment cannot remove specific effluent constituents (Amoatey & Bani, 2016). This advanced treatment removes toxic substances in the effluent, such as heavy metals, chemical compounds, biodegradable organics, bacteria, and viruses. The tertiary treatment involves various techniques as filtration, carbon absorption, distillation, reverse osmosis, the injection of chlorine, ozone, and ultraviolet (UV) irradiation, producing potable water (EPA, 1998: 5). 2.4.4 WASTEWATER RECYCLING SYSTEMS (WWRS) DESIGN IN BUILDINGS WWRS in buildings varies depending on the positioning or orientation of units, depending on a building’s typology and the number of floor levels. Figures 8, 9, and 10 illustrate specific WWRS in various buildings. In Figures 8, 9, and 10, the selected WWRS each have an OGTS below the natural ground level (NGL), such as the best practices of OGTS as indicated in Chapter 2.6.

Figure 8: Wastewater recycling system in a storey building (Raček, 2020: 1)

Figure 9: AgriNesture building wastewater recycling system (H & P Architects, 2018: 38)

Figure 10: Optimal energy-water management in urban residential buildings through greywater recycling sustainable cities and society (Wanjiru & Xia, 2017: 655) The placement of most OGTS below NGL increases the possibility of water contaminants and reduces the quality of water recycled in a building. Below NGL placements also make OGTS difficult to service. Research notes that the ratio of on-site greywater recycling in buildings is low compared to water consumption (Swilling & Annecke, 2006: 322). The author considers that the low ratio of greywater recycling in buildings is due to the economy of mass. In addition, as the OGTS is hidden (Figure 11), awareness of recycling is limited. 13

Figure 11: Typical view of a water supply point in an informal settlement (Carden, et al., 2008: 3) The study explores an alternative approach to the placement of OGTS on buildings to enhance awareness of OGTS work in urban buildings. 2.5 ON-SITE TREATMENT SYSTEMS The history of the on-site treatment systems (OTS) started with the use of pit privies (outhouses) (Figure 12). The pit privy consists of a septic tank and an outlet. The septic tank separates blackwater from settled solid to soil absorption layer for filtration. However, pit privies are primarily used in rural centres and informal squatters camp in South Africa. The modern conventional OTS implements this outhouse system into urban buildings. The conventional OTS involves primarily treating wastewater by the sedimentation of solids from wastewater. This process is also known as a subsurface wastewater infiltration system (SWIS) (Figure 13).

Figure 12: Pit privy, wastewater treatment using a septic tank (WEDC, 2002: 105 & Harvey, et al., 2002)

Figure 13: Conventional OWTS (NSFC, 2000) & Gilbert Gedeon, Port Elizabeth

Recently, various on-site treatment systems for urban buildings have been developed globally. An OGTS is developed to incorporate the sewage wastewater treatment system on a small scale (Seattle Public Utilities & Utility Systems Management Branch, 2008: 3). OGTS is cost-efficient and easily managed. An OGTS collects, treats, and recycles greywater from architectural devices in buildings. OGTS consists of preliminary, primary, secondary, and tertiary treatment processes designed to produce desirable water quality for buildings’ reuse (Seattle Public Utilities & Utility Systems Management Branch, 2008; 4). The author believes that most apartment buildings in Pretoria do not have an OGTS due to population density and large volume of greywater. In addition, in urban centres, buildings mainly connect to municipal wastewater collection for sewage treatment. 2.6 LOCAL AND INTERNATIONAL ON-SITE GREYWATER TREATMENT SYSTEMS The author selected two international and two local best practices of OGTS (Table 3). The focus of the OGTS selection is to identify its specific system features to inform the proposed OGTS yet to be designed by the author. Table 3: Selected best practices of OGTS (compiled by the author) International greywater firms (a) USA- (Biomicrobics, 2021) (b) Taiwan- (Aqua2use, 2021) Local greywater firms (c) South Africa- (Aqua aero vitae, 2021) (d) South Africa- (Biorock, 2021). 2.6.1 UNITED STATES OF AMERICA- BIOMICROBICS The United States of America (USA) is one of the most developed countries with leading technology in its sectors, prompting its selection for this study. Biomicrobics, is a company in the United States of America, Kansas state, selected as they install greywater treatment systems onto buildings. The features of the biomicrobics system are indicated in Table 4. The biomicrobics system uses “the bio-barrier membrane reactor” wastewater recycling system technology (Figure 14) (Biomicrobics, 2021). 15

Table 4: The features of Biomicrobics system

• • • • • • •

BIOMICROBICS SaniTEE Effluent Screening Device BioBarrier Membrane BioReactor BioAeration Grid System Filtrate pump Timer and High-Level Alarm floats Control Panel Installation Kit.

Figure 14: Biomicrobics on-site greywater treatment system. Country: USA (Biomicrobics, 2021)

According to Biomicrobics, the state mainly regulates greywater management in the United States of America. The building codes and regulations manage greywater before buildings are approved to be built in the country. 2.6.2 TAIWAN- AQUA2USE GREYWATER DIVERSION DEVICES Aqua2use Greywater Diversion Devices is a company in Taiwan that installs greywater diversion devices (GWDD) in buildings. The Aqua2use incorporates Matala 3D progressive filtration technology to filter greywater in buildings (Aqua2use, 2021). Figure 15 indicates the cross-sectional view and description of the Aqua2use greywater diversion device.

Figure 15: Aqua2use domestic greywater diversion devices. Country: Taiwan (Aqua2use, 2021) Table 5 indicates the features of the Aqua2use GWDD. Table 5: The features of Aqua2use system

• • • • • • • • •

AQUA2USE Fully automated system Compact device (Length 24”, Width 15”, Height 20”) that can be installed in crawl space System can be installed either above ground, semi-subterranean, or underground Built-in overflow safety system State of the art Progressive 4 Stage Filtration Built-in dry run pump protection, preventing clogging and damage to the pump Electronic Pump Controller (EPC) Diverted valve included UV resistant.

The author selected this OGTS because it has a feature that resembles the geotextile fabric used to filter greywater to achieve a better water quality for reuse. However, geotextile fabric has to be constantly changed for system maintenance. According to Aqua2use, the system placement is below the NGL, making system maintenance and service difficult to carry out. 2.6.3 SOUTH AFRICA- AQUA AERO VITAE The Aqua Aero Vitae (A2V) is a licensed company in Cape Town, South Africa that distributes water-saving technologies for a German company (INTEWA GmbH). The author selected the A2V (also known as the Aqualoop greywater treatment system, indicated in figure 16) because A2v are specialists that often treat domestic, industrial, municipal, and agricultural effluents (Aqua aero vitae, 2021). Table 6 indicates the Aqualoop OGTS features. Table 6: The features of Aqua loop system

Figure 16: Aqualoop greywater treatment system. Country: South Africa (Aqua aero vitae, 2021)

AQUA AERO VITAE • Controller- (Single membrane station controller, Multiple Membrane Station Controller with Remote Monitoring and Control) • Membrane station • Membrane cartridge • Pre-filter • Blower • Level Sensor (Float Switch, Level Pressure Sensor) • Pressure sensor, aeration • Sludge pump.

2.6.4 SOUTH AFRICA- BIOROCK The Biorock OGTS is designed to cater for a minimum of 30 persons and a maximum of 120 persons (Biorock, 2021). The author selected this system because of its capacity to cater for many households. Table 7 indicates the system features. Figure 17 illustrates the dimension and typical cross-section view of the Biorock OGTS. Table 7: Features of Biorock system

AQUA AERO VITAE • Air inlet • Air outlet • Alarm • Tipping tray • Distribution plate • Biorock media • Gravity discharge • Bioreactor • Effluent filter. Figure 17: Biorock greywater treatment system. Country: South Africa (Biorock, 2021)

2.7 BEST PRACTICES SUMMARY The specific selected international and local best practices of OGTS gave the author an appropriate understanding of the features of OGTS in buildings as summarised in Table 8. Table 8: Summary of features from the selected international and local best practices of OGTS(compiled by the author) INTERNATIONAL FIRMS (SYSTEM FEATURES) (a) BIOMICROBICS (b) AQUA2USE • • • • • • •

SaniTEE effluent screening device BioBarrier Membrane BioReactor BioAeration grid system Filtrate pump Timer and high-level alarm floats Control panel Installation kit.

• • • • • • • • • •

Fully automated system Compact device (length 24”, width 15”, height 20”) that can be installed in crawl space System can be installed either above ground, semi-subterranean, or underground Built-in overflow safety system State of the art progressive four-stage filtration Built-in dry run pump protection, preventing clogging and damage to the pump Submersible pump with integrated Electronic pump controller (EPC) Diverted valve included UV resistant

(b1)

BIO ROCK

LOCAL FIRMS ( SYSTEM FEATURES) (a1)

AQUA AERO VITAE

• Controller- (single membrane station controller, multiple membrane station controller with remote monitoring and control) • Membrane station • Membrane cartridge • Pre-filter • Blower • Level sensor (float switch, level pressure sensor) • Pressure sensor, aeration • Sludge pump.

• • • • • • • • •

Air inlet Air outlet Alarm Tipping tray Distribution plate Biorock media Gravity discharge Bioreactor Effluent filter.

In relation to Figures 12 and 13 with the selected best practices of OGTS, it can be deduced that the general practice of on-site wastewater treatment in buildings through history till date is to install the system below NGL. This could be the reason to the low ratio of water recycling to water consumption in South Africa (Binnie & Kimber, 2008: 6 & 11).

2.8 RETROFITTING BUILDINGS Dunham-Jones and Williamson (2008: 1) states that, “the conventional meaning of the word retrofit is to install parts or equipment not available during the original construction or manufacture” (Dunham-Jones & Williamson, 2008: 1). Importantly, retrofitting buildings revamps outdated building systems (Dunham-Jones & Williamson, 2008: xii). Various techniques are used depending on the purpose of the retrofit. The general purpose of retrofitting buildings is to upgrade them for effective performance. Retrofitting buildings is economically more efficient than demolishing and rebuilding on site. According to Tahsildoost and Zomorodian, (2015: 65), a building retrofit involves the following techniques: • • • • • • •

Reinforcement of a building structure (Figure 18) Installation of a building’s roof insulation for thermal comfort control Retrofit of an existing HVAC system Replacement of existing building windows to low-emissivity coated windows Re-arrangement or adaptive reuse of a space or room Addition of an extra floor to an existing building structure Installing or reinstalling an energy efficient lighting and heating system.

Figure 18 illustrates one of the listed techniques of retrofitting buildings for effective performance. In Figure 18, the building was retrofitted to reinforce its structural elements.

Figure 18: Retrofit of a building structure (Civiconcepts, 2021)

One of the techniques informs the process of retrofitting the ZF wastewater system.

2.9

CASE STUDIES 2.9.1

RETROFIT CASE STUDY 1: ZETHUSHOF FLATS BUILDING, PRETORIA

Apartment buildings are mostly tall buildings containing separate dwelling apartment units (Craighead, 2009: 551). Bhardwaj & Belali, (2015: 7) states that “Retrofitting is the process of addition of new features to older buildings” (Bhardwaj, & Belali, 2015: 7). The author explores alternative ways of designing on-site greywater treatment systems for existing apartment buildings in Pretoria to serve as a building retrofit. This study is one of the notable to adopt OGTS onto apartment buildings because of its huge volume of greywater generated. The selected apartment building in Pretoria is Zethushof Flats (ZF) (Figure 19).

Figure 19: Zethushof Flats, Pretoria- Southern view (Author, 2021)

ZF is a seventeen (17)-story student residence apartment building designed by Stauch Vorster firm in 1964 in the modernist architectural style (Emporis, 2000). It is an apartment building owned by the Tshwane University of Technology (TUT) in Pretoria. ZF is located at 620 Park Street in Arcadia, Pretoria, South Africa. ZF’s GPS location is 25°44’56.3”S, 28°12’38.0”E. According to the research design, site visits and review of the architectural drawings of the building were carried out by the author to devise a suitable approach to adopt an OGTS for ZF. At the time of the study, the author was a student resident of ZF that made it easier to access the building. Inquiries were made during site visits from PS Ntsane- the Zethushof Flats’ manager about the building because there was no found literature on ZF. The information gotten, notes that ZF was once a hotel building that was bought and retrofitted as a student apartment building by TUT. The author observed during site visits that ZF wastewater system was not considered for a retrofit during the first building retrofit. The author also observed that ZF does not have on-site greywater treatment system as at the study period. ZF relies on the sewage treatment plant in Pretoria.

2.9.2 BUILT-TO-PURPOSE CASE STUDY 2: SHARON’S PLACE, PRETORIA SP is a new apartment building designed by IBSM Architects in 2014. The building is located at 89 Lilian Ngoyi Street, Pretoria Central, South Africa. SP’s GPS location is 25°44’32.8”S, 28°11’32.8”E. The building was constructed to adopt the latest building systems and technologies to achieve a sustainable building in terms of the Green Building Council of South Africa (GBCSA). Figure 20 indicates SP building’s western view.

Figure 20: Sharon’s Place western view (Armourelite, 2021)

The SP building is one of the newest apartment buildings constructed in Pretoria at the time of the study. According to the author, SP is an appropriate local building used to compare the ZF building for retrofitting ZF’s water system. The SP’s water system is designed and built to have a secluded floor in the building for hot water recycling (Figure21).

Figure 21: Sharon’s Place secluded floor for hot water supply system, (IBSM, 2014)

The introduction of a secluded floor for hot water recycling in SP is innovative. The secluded floor does not inform the concept of retrofitting a building because it involves demolishing a floor to achieve this idea. The secluded floor could also be constructed as unit-flats instead, which could greatly benefit the building owner in terms of return on investment (ROI). The SP building does not have OGTS due to its large volume of greywater. However, it is connected to the municipal sewage treatment plant. The author considers that if most urban apartment buildings in Pretoria adopted a unique OGTS, the sewage treatment plants in Pretoria could reduce their operational load.

2.10 CONCLUSION Urban buildings should be retrofitted after a period to take advantage of new technology, improving buildings’ efficient performance. Chapter 2 introduces specific techniques for retrofitting buildings from two local and two international companies. The selected apartment building for the primary retrofitting case study is ZF in Arcadia, Pretoria that was defined in the literature review because there was no found literature on the building. The newly built SP building was selected as a comparative case study because the greywater system is purpose built into a secluded floor.

CHAPTER 3- SYSTEM DESIGN DEVELOPMENT 3.1 INTRODUCTION The focus of this chapter is on objectives 1.8.2, and 1.8.4, as listed in Table 9. Table 9: No. 1.8.2 1.8.4

Research objectives (Chapter 1)- compiled by the author Objectives To investigate the wastewater system in ZF, through site visits and architectural drawing review. To design an on-site treatment system that recycles greywater in urban apartment buildings through the selected data from the literature review (Chapter 2).

3.2 DESIGN DEVELOPMENT The purpose of chapter 3 is to focus on the design development of the proposed OGTS. The selected international and local best practices of OGTS (Section 2.6) were analysed to identify each system’s feature for adoption by the author in the design of the OGTS. Table 10: Sub-problems 3 and 4 are addressed in this chapter (compiled by the author) as follows: No.

Sub-problems (refer to chapter 1)

Sub-problem 3

How should the sewage treatment plant in Pretoria achieve reduced treatment loads of wastewater? What should be done to enhance greywater recycling in apartment buildings in Pretoria?

Sub-problem 4

3.3 SPECIFIC TREATMENT OF THE MAIN PROBLEM AND SUB-PROBLEMS (3 & 4) South Africa’s sewage treatment plants are malfunctioning or are non-functional due to their operational load pressure. 3.3.1 SUB-PROBLEM 3 It is hypothesised by this study that the recycling and recirculation of greywater in urban apartment buildings in Pretoria to flush WCs would reduce the operational load on sewage treatment plants, helping sewage treatment plants treat blackwater effectively. 3.3.2 SUB-PROBLEM 4 According to a study by Varghese, (2010: 10), the Leadership in Energy and Environmental Design (LEED) rating, a standard under the United States Green Building Council (USGBC) implements greywater building codes into their building regulation standards before buildings are approved to be built (Varghese, 2010: 10). The author emphasises that greywater-recycling building codes should also be implemented in South Africa by using the South Africa National Building Regulation (SANS 10400-XA & XB) to regulate greywater management in apartment buildings before and after they are built. This enhances greywater recycling in buildings in Pretoria and reduces the low ratio of water consumption to greywater recycling.

3.4 PHASE 2.1: BACKGROUND Table 11 summarises the research design, highlighting the pertinent aspects to be addressed in Chapter 3. Table 11: Summary of the research design, Phase 2.1 (Compiled by the author) PHASE 2.1: Theme:

SYSTEM DESIGN DEVELOPMENT (Chapter 1) On-site greywater recycling system design

Focus area:

Case study investigation, conceptual sketching, and system designing

Data source: Electronic media, paper sketches, architectural drawing, and Autodesk Revit2.1.1 2.1.2 2.1.3

To investigate the existing wastewater system in the Zethushof- Flats through architectural drawing review and site visits To identify the features of the selected international and local best practices of OGTS (Section 2.15) to inform the conceptual sketches of an alternative OGTS To finalise the conceptual sketch of the on-site greywater recycling system.

1: 100 0

10m

15m

20m

25m

Figure 22: Zethushof fifth floor plan indicating the wastewater duct point (Fgure 24 or Section x-x) drawn to scale 1: 100 (Author, 2021) adapted from TUT Architecture department resource

NORTH

3.4.1 ZETHUSHOF FLATS’ WASTEWATER SYSTEM FOR A RETROFIT

Figure 22 indicates the ZF fifth-floor plan, indicating the duct point where wastewater pipes are located.

3.4.2 EXISTING ZETHUSHOF FLATS’ WASTEWATER SYSTEM Figure 23 illustrates the existing ZF’s wastewater system (Section X-X, floorplan in Figure 22).

Figure 23: Zethushof Flat’s wastewater system drawn from section X-X in figure 23 to scale 1: 100 (Author, 2021)

The ZF is one of the notable existing apartment buildings in Pretoria to be considered by this study for adopting a unique and detailed OGTS. The author notes that ZF wastewater system requires a retrofit after several site visits. Figures 24 and 25 indicate the situation of ZF’s wastewater system.

Figure 24: Zethushof Flat’s wastewater system (Author, 2021)

Figure 25: Effects of the Zethushof Flat’s wastewater system (Author, 2021)

The existing wastewater system in the ZF are slightly exposed with two elbowed pipes below the first-floor level. The orientation of the wastewater system in the ZF has led to the increased splashing of wastewater to the building’s external wall close to the car park (Figure 24 & 25). This has thereby resulted to the present wall and slab cracks (Figure 25) and this might lead to the building’s structural damage in a long run. 3.4.3 COMPARISON BETWEEN SHARON’S PLACE AND ZETHUSHOF- FLATS WASTEWATER SYSTEM The SP building has its wastewater system fully enclosed into ducts and channelled down to the municipal sewage treatment plants (Figure 26).

Figure 26: Sharon’s Place wastewater system (IBSM, 2014)

ZF has its wastewater system slightly exposed with two elbowed pipes underneath the building’s ground floor (Figure 27). Figure 27: Zethushof flat’s wastewater system (Author, 2021)

SP’s compactible duct system was considered at the preplanning stage of the building (Figure 26), while ZF’s duct system was not (Figure 27). Thus, the ZF duct system was an ‘afterthought’ system. To retrofit the existing ZF wastewater system, the elbowed pipes (Figures 24 and 27), should be covered into ducts all through to the ground floor such as SP’s duct system. This would reduce the splashing of wastewater and reduce the chances of students contacting harmful diseases expelled to the environment. 27

3.4.4 PROPOSED SYSTEM DESIGN A quote by Buckminster Fuller (Wible 2007: 281) states that “the best way to predict the future is to design it”. The author’s concept of the proposed OGTS design expresses “a living building”. Mclennan (2004: 8) states that the buildings we live in will be constructed in the future to conceptually mimic living organisms in their function to the requirement for energy and water by sourcing from renewables (re) such as the sun, rain, and wind (Mclennan, 2004: 8). An example of a living organism is the concept of how flowers photosynthesise energy from the sun to grow (Mclennan, 2004: 8). The author considers that a living building should be autonomous and should enhance its occupants’ experience and wellbeing to depict the concept of living organisms. It is observed that most building systems such as lighting, HVAC, and OGTS are hidden in buildings . The installation of building systems does not consider users’ understanding, resulting in a low ratio of water recycling to water consumption in urban buildings. The features of building systems should be didactic to facilitate users’ understanding. Therefore, the proposed OGTS functions autonomously to interact with residents of urban apartment buildings to facilitate awareness and enhance greywater treatment operation. The proposed OGTS envisaged is mounted onto apartment building facades in Pretoria and does not interfere with the building structure. This idea informs the facade view of various apartment buildings in Pretoria when the proposed system is implemented. The proposed OGTS is designed to explore the pulley mechanism to address the challenges faced by most wastewater systems and infrastructure, such as energy consumption (EPA, 1998). The author orientates the proposed system to reduce the energy and pressure on force pumps raising water from a lower level to the highest floor level of an apartment building via a pulley mechanism (Figure 29). Figure 28 illustrates the first conceptual sketch of the proposed OGTS for apartment buildings in Pretoria.

Floor level 2 (+3000) Pulley system greywater pipe from building

Floor level 1

LEGEND A- Preliminary treatment phase B- Main treatment phase C- Recycling phase

Figure 28: First conceptual 2D sketch on elevation view to be mounted onto Zethushof façadenot to scale (Author, 2021)

Figure 29 illustrates the first conceptual sketch in motion to express the autonomous idea of the proposed OGTS via pulley mechanism. Floor level 2 (+3000) Pulley system greywater pipe from building

LEGEND A- Preliminary treatment phase B- Main treatment phase C- Recycling phase

greywater

Floor level 1

Figure 29: First conceptual 2D sketch (in motion)- elevation view to be mounted onto Zethushof façadenot to scale (Author, 2021)

The proposed OGTS operates via a pulley mechanism on the ZF facade to move treated water to every fifth floor connected to WC cisterns. The proposed first conceptual sketches in Figures 28 and 29 had many iterations because the author’s idea was to move the treated water (recycling phase) to every floor level without having system leakage. The author later finalised a second conceptual sketch (Figure 30). Floor level 6 (+15000)

Pulley system

Floor level 5 (+12000)

greywater pipe from building

F Floor level 4 (+9000)

Counterweight to move the recycling tank

Floor level 3 (+6000)

F Floor level 2 (+3000)

E Floor level 1

B C D

Figure 30: 2D view of the finalised conceptual sketchnot to scale (Author, 2021)

LEGEND A- Greywater storage tank B- Preliminary treatment tank C- Main treatment tank D- First storage tank E- Recycling tank F- Second storage tank on every floor SYSTEMS DESCRIPTION- specific numbers of litres of greywater from a building flows into the greywater storage tank (A) to control the litres of greywater flowing to the preliminary treatment tank (B). Substantial litres of grey water then flows into the preliminary treatment tank through to the first storage phase (B to D) of the proposed system. The filtered water then flows into the recycling phase (E) of the proposed system into the second storage phase on every floor to be recirculated for flushing water closets (wc).

According to the author, the finalised conceptual sketch (Figure 30) is more manageable than the first two sketches (Figure 28 and 29) for addressing the system leakage factor. Figure 31 illustrates the system’s schematic diagram in relation to the finalised conceptual sketch.

LEGEND

Process 1

Process 2

Process 3

Greywater from specific units of the building is collected to the preliminary phase of the system. The effluent further flows into the second phase for effective treatment of water using fine sand filters. The filtered water later flows to the storage tank below the treatment phase. The treated water in the third process is recycled to the storage tanks on each floor for flushing WCs.

Figure 31: 2D view of the proposed system schematic diagram drawn to scale 1:100 (Author, 2021)

3.5 PHASE 2.2: DESIGN DEVELOPMENT In this phase of Chapter 3, the proposed system capacity is defined by calculation using ZF-derived figures. Table 12 illustrates the research design Phase 2.2. Table 12: Summary of the research design, referring to Phase 2.2 (Compiled by the author) PHASE 2.2 (Chapter 3) Theme: On-site greywater recycling system capacity Focus area:

Defining the designed system capacity using the Zethushof Flat’s (ZF)

Data source: Electronic media, SANS 10400 -XA and greywater calculation 2.2.1 To analyse the occupancy and population of each apartment unit in ZF in accordance with SANS 10400 -XA: 2011 2.2.2 To calculate ZF’ greywater generated daily and weekly per household 2.2.3 To explore the volume and dimension of the proposed system for ZF 2.2.4 To model the finalised conceptual sketch of the system on Autodesk Revit- . 3.5.1 OGTS CAPACITY The proposed OGTS capacity was determined using ZF’s occupancy and population (Table 13) and analysed using SANS 10400-XA: 2011. This capacity determination was done to avoid the system overload of the proposed OGTS. Table 13- Occupancy or Building Classification- SANS 10400-XA: 2011 (redrawn by the author) 2 1 Class of Occupancy occupancy of building Hotel H1 Occupancy where persons rent furnished rooms, not being dwelling units H2 H3

Dormitory Occupancy where groups of people are accomodated in one room Domestic residence Occupancy consisting of two or more dwelling units on a single site.

Table 14 – Design Population- SANS 10400-XA: 2011 (redrawn by the author) 1 2 Class of occupancy of Population room or storey or portion thereof A1, A2, A4, A5 Number of fixed seats or 1 person per m2 if there are no fixed seats E1, E3, H1, H3 2 persons per bedroom 1 person per 15m2. G1 ZF is categorised as ‘H3’ and ‘Domestic residence’ according to SANS 10400-XA: building occupancy and population. ZF’s occupancy and population were analysed using the SANS standard to determine the number of households that a dwelling unit of ZF represents in the proposed OGTS. Thus, the litres of greywater from each unit of the ZF building can be calculated. 31

3.5.2 ZETHUSHOF FLATS’ GREYWATER CALCULATION Zethushof Flats’ (ZF) is a student apartment with 17 floors and 12 units on each floor level. Greywater sources in the ZF are from the following: • • •

Bathing (from bath tubs or showers) Hand washing (wash hand basins- whb) Laundry (washing machine or hand washing).

The study focuses on recycling the greywater from the ZF for flushing WCs. According to Waterwise, figure 32 notes the average litres of water used in a household of four (4) in South Africa.

• •

ASSUMPTIONS ON WATER USAGE Water closets uses 15 litres of water per flush Each showerhead uses 15 litres per minute heads for a 7-minute shower equals 105 litres Wash hand basin is 2 litres per use Laundry handwash is 15 litres per use.

Figure 32: water use for a family of four in South Africa (Waterwise, 2021) According to Bladder & Bowel Community, a person may urinate between six to seven times per day, depending on their fluid intake, and this number could range from four to ten times (Bladder & Bowel Community, 2018) (Figure 41). Also, Gallan notes that a person may defecate between three times per day to three times per week (Gallan, 2017). 3.5.3 • • • •

ASSUMPTIONS

An average person urinates four times a day and defecates once a day – five uses of the WC For every use of the WC, it is always assumed that the wash hand basins are used four times for handwashing. In addition, the COVID-19 handwashing protocol of once for every flush, making handwashing five times to every one flush of the WC Occupants shower once a day Occupants do laundry once a week.

Table 15 indicates the average greywater use from a unit flat in the ZF per day, and per week, according to Waterwise- figure 33. The calculated average greywater in Table 15 informs the volume of the proposed OGTS capacity for the ZF building. Table 15: Greywater calculation (Waterwise- figure 33)- (compiled by the author) Fixture usage One person

Shower Litres

Daily average (per person)

105

Wash handbasin Litres

Laundry Litres

n/a

=115 litres/ day/ person

Four persons 105 x 4= 420 10 x 4= 40 15 x 4= 60 =520 litres/ week/ unit flat (per unit flat) (per week) Four persons/ 420 x 4= 1680 40 x 4= 160 60 x 4= 240 (four unit flat) Total greywater 1, 680 + 160 + 240 =2, 080 litres/ day/ four per unit flat units flat. According to table 15, the calculation of the smallest tank in the proposed OGTS is 2,080 litres, However, the author proposes a 2,500 litres tank for water overflow. The proposed OGTS is designed to have six tanks, so each tank’s capacity is defined in Table 16. Table 16: Entire tank capacity in relation to its dimension (Figure 35 to 40)-(compiled by the author) Preliminary

Main treatment

First storage

Recycling

Second storage

treatment tank (mm)

tank (mm)

V= L x B x H V=900 x 400 x 700 V= 252,000,000 V= 2,520 litres

V= L x B x H V=900 x 400 x 800 V= 288,000,000 V= 2,880 litres

The designed tank for preliminary treatment will be approximately 2,500 litres

The designed tank for main treatment will be approximately 2,500 litres

The designed tank for the first storage will be approximately 2,500 litres

The designed tank for recycling will be approximately 3,000 litres

The designed tank for the second storage will be approximately 3,000 litres

Greywater storage tank (mm) V= L x B x H V=900 x 400 x 800 V= 288,000,000 V= 2,880 litres The designed tank for the greywater storage will be approximately 3,000 litres.

Table 17 summarises the tanks’ capacity (litres) for the proposed OGTS. Table 17: Summary of the designed tanks’ capacity in litres- (compiled by the author) Preliminary

Main treatment

First storage

Recycling

Second storage

Greywater storage

treatment tank

tank

2,500 litres

3,000 litres

3.5.4 DEFINING THE SHAPE OF EACH TANK THROUGH SKETCH The shape of each tanks in the proposed OGTS- treatment phase was designed carefully to be assemble into a single unit because it is to be mounted onto ZF’ facade. The author was inspired by the Zaha hadid- parametric style of architecture which was reflected in the shape of the system. Figure 33 illustrates the author’s sketch of each tanks in relation to the proposed systems’ schematic diagram in figure 32 and the calculated tanks’ capacity in table 16. Pipe

Greywater storage tank (3000 litres)

Preliminary treatment tank (2500 litres)

Pipe

Recycling tank (3000 litres)

Main treatment tank (2500 litres)

The assembled designed system- treatment phase

First storage tank (2500 litres)

Figure 33: Sketch proposal of the designed OGTS- not to scale (Author, 2021)

Pipe

Second storage tank (3000 litres)

Figures 34 to 39 indicates the dimensioning of each component of the designed system in relation to the sketches in figure 33 and the calculated tank capacity in table 16.

Figure 34: Preliminary treatment tank dimension- Isometric & elevation views- drawn to scale 1:100 (Author, 2021)

Figure 35: Main treatment tank dimension- Isometric & elevation views- drawn to scale 1:100 (Author, 2021)

Figure 36: First storage tank dimension- Isometric & elevation views- drawn to scale 1:100 (Author, 2021)

Figure 37: Recycling tank dimension- Isometric & elevation views- drawn to scale 1:100 (Author, 2021)

Figure 38: Second storage tank dimension- Isometric & elevation views- drawn to scale 1:100 (Author, 2021)

320

Figure 39: Greywater storage tank dimension- Isometric & elevation views- drawn to scale 1:100 (Author, 2021)

3.6 TANK ASSEMBLY OF THE DESIGNED OGTS OF THE TREATMENT PHASE Figure 40 illustrates the assembly of each tank in the OGTS as dimensioned in figures 34 – 39.

Preliminary treatment tank (2500 litres)

Main treatment tank (2500 litres)

First storage tank (2500 litres)

Figure 40: Tank assembly- front and isometric view are drawn to scale 1: 100 (Author, 2021)

An OGTS requires oxygen for system aeration to treat greywater effectively, as indicated in Section 2.6 – International best practices of OGTS. Oxygen is also required in OGTS to reduce the foul odour expelled and avoid system explosion. The air vents were added to the preliminary treatment phase of the designed system (Figure 41) for these reasons. In addition, to prevent birds from perching or building nests on the added air vents to the greywater system, aluminium air vent covers were added to avoid the deposit of bird waste into the system. Figure 41 illustrates the added air vents covering the system on isometric and elevation views.

Air vent cover to prevent bird’s waste into the system

Top view showing through air vent

Side view

Isometric view

Figure 41: Air vent cover for the designed system. Front and isometric view are drawn to scale 1: 100 (Author, 2021)

3.7 VIEWS OF THE DESIGNED OGTS OF THE TREATMENT PHASE Figures 42 to 45 illustrates specific views of the designed OGTS of the treatment phase.

Figure 42: Top view (left) and bottom view (right) of the treatment phase are drawn to scale 1:100 (Author, 2021)

Figure 43: Elevation view. Front, rear, right, and left of the treatment phase are drawn to scale 1:100 (Author, 2021)

Figure 44: Isometric view. Left, right, and rear of the treatment phase is drawn to scale 1:100 (Author, 2021)

Figure 45: Left, right, and rear of the fish-eye view of the treatment phase are drawn to scale 1: 100 (Author, 2021)

3.8 MATERIAL SPECIFICATION FOR EACH PIPE IN THE DESIGNED OGTS In an attempt to determine the right material for the pipes in the designed system, the author adopted a comparative study approach to select a suitable pipe material. 3.8.1 GALVANISED STEEL PIPE Corrosion in the presence of oxygen is the main cause of galvanised steel pipes in water supply systems being destroyed (Andrianov & Spitsov, 2017). 3.8.2 DUCTILE IRON (DI) PIPE Runge (2014) notes that ductile iron pipe material has sustainability, durability, and cost-effectiveness properties. This pipe material is composed of 95% recycled scrap steel and iron. It is manufactured with a sophisticated coating and strong encasement, making it reliable for water supply service (Runge, 2014). 3.8.3 PLASTIC PIPES: unplasticized Polyvinyl chloride (uPVC) and polyvinyl chloride (PVC) Plastics are utilized in a variety of commercial and industrial applications. Unplasticized polyvinyl chloride (uPVC), polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), acrylonitrile– butadiene–styrene (ABS), glass–fibre–reinforced polyester (GFRP), and polybutylene (PB), are the most well-known. However, uPVC, PVC, and PE are the most common polymer materials used in piping systems for sewage disposal, drinking water, and gas distribution (Plastics Europe, 2017). PVC material is composed of plastic and vinyl. PVC has a fire resistance of 30% to 65% and at the occurrence of fire outbreaks, It produces toxic by-products that are harmful to the environment (Coolingtowerinfill, 2018). PVC has a tensile strength of 1.4 MPa (Kabir et al., 2006) and low thermal conductivity of 0.12-0.25 @23C (Takisawa et al., 2011). The differences between PVC and uPVC is that PVC consists of BPA and phthalates- responsible for it’s flexible nature. uPVC (unplasticized PVC) does not have BPA and phthalates material that makes it rigid in nature (Hunker, 2019). Unplasticized polyvinyl chloride (uPVC) pipe and polyvinyl chloride (PVC) pipe were selected out of the various polymer materials for the comparative study. Table 18 indicates the comparison of uPVC and PVC materials. 39

Table 18: Comparison between uPVC and PVC material- (compiled by the author) Criteria Life span

uPVC material uPVC has a long-life span of 100 years compared to PVC material because of its rigid nature (Pvc4pipes, 2021).

PVC material Low life span compared to uPVC material (Makris et al., 2020).

uPVC has a low thermal conductivity of Thermal Conductivity 0.12-0.25 @ 30C (S-lon, 2013: 7).

PVC has a low thermal conductivity of 0.12-0.25 @23C (Takisawa et al., 2011).

Tensile strength

PVC has a tensile strength of 1.4 MPa (Kabir et al., 2006).

uPVC has a tensile strength of 10 and 12.5 MPa (S-lon, 2013: 7).

3.8.4 SELECTED MATERIAL: DUCTILE IRON According to the previous studies on galvanised steel pipe, ductile iron pipe and polymer pipes, it can be deduced that ductile iron (DI) pipe material is reliable for implementation into the designed system because of its strength and long lifespan compared to other selected piping materials. Therefore, the author selects ductile iron (DI) pipe material for both the greywater pipe (inlet) and the treated water pipe (outlet). The author proposes a 50mm diameter ductile iron (DI) pipe for both greywater (inlet) and treated water (outlet) (Figures 46 and 47) to control water pressure and flow rate from every five floors in the ZF’ building into and out of the designed system. In addition, two 100mm diameter ductile iron (DI) pipe for the air vent attached to the designed system to allows oxygen into the preliminary treatment process of the designed system (Figure 48). Figure 46 illustrates the material specification of the pipes in the designed system. 110mm diameter ductile iron pipe for air vent

40mm diameter ductile iron pipe (from the building through the 230 external wall) for freshwater supply into the preliminary treatment tank to mix with the effluent 50mm diameter ductile iron wastewater (in55mm diameter rubber gasket

Figure 46: Pipe specification of the designed system on an isometric view drawn to scale 1: 100 (Author, 2021)

50mm diameter ductile iron treated water pipe supply for flushing toilets (outlet)

Tank connected to recycling tank

ISOMETRIC REAR VIEW

50mm diameter ductile iron treated water pipe supply for flushing toilets (outlet)

ISOMETRIC FRONT VIEW

Figure 47: Pipe specification of the designed system- final storage tank on an isometric view drawn to scale 1:100 (Author, 2021)

3.9

MATERIAL SPECIFICATION OF THE TANKS

The author explored specific tank materials such as unplasticized polyvinyl chloride (uPVC), polyethylene terephthalate (PET), and High-density polyethylene (HDPE). The material repertoire was compared according to research to choose the best material. 3.9.1 UNPLASTICISED POLYVINYL CHLORIDE (uPVC) Unplasticized polyvinyl chloride (uPVC) is a rigid PVC pipe- widely used polymer material for construction, water supply and sewage drainage in buildings. Wei (2021: 2) states that uPVC out of other plastic pipe material “...is not good in temperature resistance performance. It has poor compressive strength and cannot be used in high-rise buildings” (Wei, 2021: 2). 3.9.2 POLYETHYLENE TEREPHTHALATE (PET) Polyethylene terephthalate (PET) is a naturally transparent semi-crystalline material widely used commercially to manufacture plastic bottles (Omnexus, 2021). PET has a tensile strength of 3.31 MPa (Irwan et al., 2014) and thermal conductivity of 0.15-0.4 @23C (Takisawa et al., 2011). 3.9.3 HIGH DENSITY POLYETHYLENE (HDPE) HDPE is a plastic material with impact resistance and has a tensile strength of 27.3 MPa (Claude et al., 2010). HDPE material has a waterproofing property that makes it reliable tank material to avoid tank leakage. HDPE material has a thermal conductivity of 0.938 W/m.K (Tavman et al., 2011). The author selected the Polyethylene terephthalate (PET) for the visible components of the system, and High-density polyethylene (HDPE) out of the various polymer materials for a comparative study of material specification for each tank in the designed system. The table 19 shows a comparison between PVC, PET, and HDPE materials. Table 19: Comparison between uPVC, PET, and HDPE material- (compiled by the author) Criteria Strength

uPVC material

PET material

uPVC has a tensile strength PET has a tensile strength of of 12.5 MPa (S-lon, 2013: 7). 3.31 MPa (Irwan et al., 2014).

HDPE material HDPE has a tensile strength of 27.3 MPa (Claude et al., 2010).

uPVC has a low thermal con- PET has a thermal conductivity of HDPE has a thermal conductivity Thermal ductivity of 0.12-0.25 @ 30C of 0.938 W/m.K (Tavman et al., 0.15-0.4 @23C (Takisawa et al., 2011). conductivity (S-lon, 2013: 7). 2011).

3.9.4 SELECTED MATERIAL: PET AND HDPE According to the previous data in Section 3.9, the author deduced that high-density polyethylene (HDPE) is reliable enough to adopt in the designed system because of its strength and long lifespan compared to other materials. Therefore, the author selected high-density polyethylene (HDPE) material for all the tanks in the designed system. The HDPE material was also selected because it has a higher thermal capacity for excessive solar radiation than other materials. The author selected polyethylene terephthalate (PET) for the visible component of the designed system of the treatment phase (Figure 48). The author’s selection of PET is to have the primary treatment tank visible to create awareness of the designed system’s greywater treatment process. In addition, the PET material was selected to adopt the use of ultraviolet (UV) light from the sun to treat greywater in addition to the filters in the designed OGTS.

3.10 FULL DESCRIPTION OF THE DESIGNED OGTS OF THE TREATMENT PHASE Figure 48 illustrates the full description of the designed system- treatment phase. Aluminium air vent cover to prevent bird’s waste into the system 40mm diameter ductile iron pipe (from the building through the 230 external wall) for freshwater supply into the preliminary treatment tank to mix with the effluent 50mm diameter ductile iron greywater pipe (inlet) 55mm diameter rubber gasket 2500 litres main treatment HDPE tank

2500 litres main treatment HDPE tank Tank connector to recycling tank

700mmm x 480mm x 10mm thickness custom made PET visible material placed into the specific component of the main treatment tank for system visibility 2500 litres first storage HDPE tank

Figure 48: Full description of the designed system of the treatment phase on isometric view drawn to scale 1:100 (Author, 2021)

3.11 FILTER SPECIFICATION OF THE DESIGNED OGTS- MAIN TREATMENT PHASE The author was very careful in the decision making of a greywater filter system because of its weight that adds to the weight of the designed system of the treatment phase. A comparative study was made between sand and cartridge filters (mainly for filtering pool water) to determine the suitable system by exploring the pros and cons. Table 20 illustrates a comparison between sand filters and cartridge filters. Table 20: Comparison between sand filters, and cartridge filters (compiled by the author) FILTERS ADVANTAGES SAND FILTERS

Cheap and simple treatment filter that removes total organic matter (TOM) of 40.3% at 10.44mg/L TOM (Abbasi-garravand et al., 2015)

CARTRIDGE Advanced treatment system mainly used by wastewater treatment plants to remove chemicals (PreciFILTERS sionFiltration.com, 2011).

DISADVANTAGES Low organic removal compared to cartridge filters. Also, it takes time to filter (Collins et al., 1991). Not cost-efficient, and cartridges must be cleaned frequently, which is not effective as regards maintenance (Dvorak, 2013).

According to Table 20’s comparative study, the author deduced that sand filters are reliable to adopt in the designed system of the treatment phase because the filters are the simplest and cheapest filter system when compared to cartridge filters. The maintenance factor is not an issue for sand filters compared to cartridge filters. The author selects sand filters for the designed system. The treatment phase as illustrated in the cross-sectional perspective of the designed system in figure 49. 3.12 CROSS-SECTION PERSPECTIVE OF THE DESIGNED OGTS Figure 49 illustrates a cross-section of the designed system and its specific description.

110mm diameter ductile pipe for air vent

Aluminium air vent cover to prevent bird’s waste into the system 40mm diameter ductile iron pipe (from the building through the 230 external wall) for freshwater supply into the preliminary treatment tank to mix with the effluent 50mm diameter ductile iron greywater pipe (inlet) 55mm diameter rubber gasket

Sand filters for effluent that flows into the preliminary and main treatment tank

4mm diameter filter perforation 20mm diameter filter perforation 2500 litres preliminary treatment HDPE tank 2500 litres main treatment HDPE tank

2500 litres first storage HDPE tank

Figure 49: Cross section perspective of the designed OGTS of the treatment phase is drawn to scale 1:100 (Author, 2021)

3.13 FLOW DIAGRAM OF THE DESIGNED OGTS OF THE TREATMENT PHASE Figure 50 illustrates the flow diagram of the designed OGTS of the treatment phase process.

foul smell emission and oxygen inlet for system aeration

calculated litres of greywater from the building to the system

unfiltered greywater from greywater storage tank flows into the preliminary treatment system

50mm diameter ductile greywater pipe (inlet)

phase change from greywater to slightly filtered water

50mm diameter ductile greywater pipe (inlet)

40mm diameter ductile iron pipe (from the building through the 230mm external wall) for freshwater supply into the preliminary treatment tank to be mixed with 4mm diameter filter perforation 20mm diameter filter perforation 2500 litres preliminary treatment HDPE tank

Sand filters for effluent preliminary treatment final phase change to filtered water

Filtered water later flows into the recycling tank connected to the first storage tank

2500 litres main treatment HDPE tank

2500 litres first storage HDPE tank

Figure 50: Flow diagram of the designed OGTS of the treatment phase is drawn to scale 1:100 (Author, 2021) LEGEND Unfiltered greywater from the building Slightly filtered greywater with sand filter Well filtered/ clean water for the purpose of flushing water closets (wc) Fine sand filter

Greywater from the greywater storage tank (Figure 52 and 53), flows into the preliminary treatment tank. The effluent then passes through the first fine sand filter in the system and mixes with the fresh water supply (a catalyst) from a building. The effluent is slightly filtered at this phase. The effluent flows into the second fine sand filter in the system and flows into the main treatment tank. The effluent flows into the third fine sand filter in the system and flows into the first storage tank of the designed treatment phase of the system to recycle to every floor to WC cisterns. 44

3.14 EXPLODED VIEW OF THE DESIGNED OGTS OF THE TREATMENT PHASE Figure 51 illustrates the exploded view of the designed OGTS of the treatment phase. LEGEND

2 3 4 5

6 7

50mm diameter ductile iron greywater pipe (inlet) Aluminium air vent cover to prevent bird’s waste into the system

Aluminium air vent

110mm diameter ductile iron pipe for air vent 40mm diameter ductile pipe (from the building through the 230mm external wall) for freshwater supply into the preliminary treatment tank to be mixed with greywater

1 1

2500 litres preliminary treatment HDPE tank 4mm diameter filter perforation

Fine sand filter

2500 litres main treatment HDPE tank

2500 litres first storage HDPE tank with tank connector to recycling tank (outlet).

Figure 51: Exploded view of the designed OGTS of the treatment phase drawn to scale 1:100 (Author, 2021)

3.15 FULL PROTOTYPE AND LAYOUT OF THE DESIGNED OGTS FOR APARTMENT BUILDINGS Figure 52 illustrates the front view of the designed OGTS layout to be mounted onto ZF’ façade. LEGEND

A B

50mm diameter ductile iron greywater pipe (inlet) 3000 litres greywater storage HDPE tank for system control. 110mm diameter ductile iron pipe for air vent with aluminium cover 2500 litres preliminary treatment HDPE tank 2500 litres main treatment HDPE tank

2500 litres first storage HDPE tank

Tank connector to recycling tank

H I

3000 litres recycling tank to each floor level Travelling cables connected to pulley system

Steel counterweight rails

Steel counterweight with 50kg iron bars each

3000 litres second storage tank connected each water closet cisterns on a floor level.

A B C D

K J I D E H

F G

Figure 52: Front view of the layout of the designed OGTS drawn to scale 1:100 (Author, 2021)

Figure 53 illustrates an isometric view of the layout of the designed OGTS.

LEGEND

2500 litres first storage HDPE tank

Tank connector to recycling tank

H I

3000 litres recycling tank to each floor level Travelling cables connected to pulley system

Steel counterweight rails

Steel counterweight with 50kg iron bars each

3000 litres second storage tank connected each toilet cisterns on a floor level.

B C

D A

D H

E G

Figure 53: Isometric view of the layout of the designed OGTS drawn to scale 1:100 (Author, 2021)

3.16 COMPARISON BETWEEN THE DESIGNED OGTS AND THE SELECTED BEST PRACTICES OF OGTS Table 21 indicates the comparison between the selected international and local best practices of OGTS (Chapter 2) and the designed OGTS. Table 21: Comparison between the designed OGTS and selected best practices of OGTS(compiled by the author) CRITERIAS

FEATURES

DESIGNED OGTS • • • •

System visibility Autonomous system (recycling phase) Two storage tanks One greywater storage tank for system control.

SELECTED BEST PRACTICES OF OGTS (BIOROCK SYSTEM, BIOMICROBICS, AQUA AERO VITAE, & AQUA2USE) • • •

While all the selected systems have no visible component All have fixed systems All have one storage tank.

3.17 FINDINGS The designed OGTS when mounted onto several apartment buildings enhances awareness of greywater recycling works in Pretoria. This mounted system increases the ratio of on-site wastewater recycling to water consumption in apartment buildings in Pretoria. In addition, the designed OGTS enhances the ratio of on-site wastewater recycling compared to water consumption in the buildings. 3.18 CONCLUSION This chapter addressed objectives 1.8.2, and 1.8.4, as listed in Chapter 1: Table 22: Research objectives from Chapter 1 (compiled by the author) No. Objectives 1.8.2 1.8.4

To investigate the wastewater system in ZF through its architectural drawings and site visits. To design an on-site treatment system that recycles greywater in urban apartment buildings through the selected data from the literature review (Chapter 2).

CHAPTER 4- SYSTEM APPLICATION This chapter focuses on the system application of the designed OGTS onto urban apartment buildings in Pretoria, as labelled in the phase 3 of the research design in Chapter 1. 4.1 INTRODUCTION Objective 1.8.5 and sub-problem 4 are addressed in this chapter. Table 23: Review of research objective 1.8.5 from Chapter 1- (compiled by the author) No. 1.8.5

Objectives To design an on-site greywater treatment system (OGTS) design blueprint for mounting onto diverse urban apartment buildings in Pretoria.

Table 24: Review of sub-problem 4 (compiled by the author) Sub-problem 4 What should be done to enhance wastewater recycling in urban apartment buildings in Pretoria?

Hypothesis 4 It is hypothesised that wastewater recycling in urban apartment buildings in Pretoria would be enhanced if an appropriate system is designed to adopt an on-site wastewater treatment system (OGTS).

4.2 REVIEW OF THE RESEARCH DESIGN The research design is reviewed in table 25. Table 25 assists the reader with a summary of the research design, highlighting the pertinent phase to be addressed in Chapter 4. Table 25: Summary of the research design, referring to Phase 3 (Compiled by the author) PHASE 3: Theme:

SYSTEM APPLICATION On-site greywater recycling system installation

Focus area:

Fixing of the proposed system to Zethushof Flat’s (ZF)

Data source: Architectural drawings 3.3 To design the mounting structural elements holding the designed ogts onto ZF’ façade 3.4 To explore the approach of splitting the designed OGTS onto the ZF’ facade and floor

4.3 MOUNTING DETAILS OF THE FIXED COMPONENTS OF THE DESIGNED OGTS In an attempt to mount the designed OGTS onto ZF’ façade, offsets of 50mm x 50mm x 5mm thickness were added to the rear of each tank to allow the bolts and nuts- head to fit onto ZF’ facade and to any apartment building’s façade in Pretoria. Figures 54 to 56 illustrates the offsets to the rear of each tank and figure 57 illustrates the assembled OGTS after these offsets were made.

50mm x 50mm x 5mm thickness- offset to allow the sitting of the bolts and nuts head in place unto each tank

Figure 54: Preliminary treatment tank. Isometric view front and rear are drawn to scale 1:100 (Author, 2021)

50mm x 50mm x 5mm thickness offset to allow the sitting of the bolts and nuts head in place unto each tank

Figure 55: Main treatment tank. Isometric views of the front and rear are drawn to scale 1:100 (Author, 2021)

50mm x 50mm x 5mm thickness offset to allow the sitting of the bolts and nuts head in place unto each tank

Figure 56: First storage tank. Isometric views of the front and rear are drawn to scale 1:100 (Author, 2021)

Figure 57: Assembled OGTS of the treatment phase (rear, rear-isometric & rear-isometric fisheye view)- scale 1:100 (Author, 2021)

4.3.1 SKELETAL STRUCTURES HOLDING THE DESIGNED OGTS IN PLACE TO ZETHUSHOF FLATS’ FACADE The author further designed mounting skeletal structures to hold in place the designed OGTS of the treatment phase onto ZF’s facade (Figure 58). X

FRONT VIEW

LEFT VIEW

RIGHT VIEW

Figure 58: Skeletal structure (elevation view)- scale 1:100 (Author, 2021) LEGEND

X Y Z

25mm thick vertical C- section aluminium bracket mechanical fastreed with M16 x 50mm bolts and nuts to the building facade 10mm thick horizontal C- section aluminium bracket mechanical fastreed with M16 x 50mm bolts and nuts to the building facade 25mm thick vertical L- section steel stand mechanical fastreed with M14 x 50mm bolts and nuts to the building facade.

Figure 59 illustrates the mounting skeletal structure details of the designed OGTS of the treatment phase on left fish eye view. 25mm thick vertical C- section aluminium bracket mechanical fastreed with M16 x 50mm bolts and nuts to the building facade

10mm thick horizontal C- section aluminium bracket mechanical fastreed with M16 x 50mm bolts and nuts to the building facade

25mm thick vertical C- section aluminium bracket mechanical fastreed with M16 x 50mm bolts and nuts to the building facade 25mm thick vertical L- section steel stand mechanical fastreed with M14 x 50mm bolts and nuts to the building facade

Figure 59: Mounting skeletal structure of the treatment phase to a wall. The left fisheye view drawn to scale 1:100 (Author, 2021)

Figure 60 illustrates a description of the mounting skeletal structure of the designed OGTS’ second storage tank on elevation views. W

LEFT VIEW

FRONT VIEW

RIGHT VIEW

Figure 60: Second storage tank. Drawn on elevation view to scale 1:100 (Author, 2021) LEGEND

W Z

Figure 61 illustrates a description of the mounting skeletal structure of the OGTS- second storage tank using an isometric view. 25mm thick vertical C- section aluminium bracket mechanical fastreed with M16 X 50mm bolts and nuts to the building facade (labelled as W)

Figure 61: Mounting skeletal structure of the second storage tank (left fisheye view) drawn to scale 1:100 (Author, 2021)

4.3.2 DESIGNED OGTS MOUNTED ONTO ZF’ FAÇADE Figure 62 illustrates the designed OGTS of the treatment phase, second storage, and greywater storage tank mounted to ZF’ façade.

L L

F D E

E F

FRONT VIEW

FISH EYE VIEW (LEFT)

FISH EYE VIEW (RIGHT)

Figure 62: The designed OGTS of the treatment phase and second storage tank mounted onto a wall façade (fisheye & front view) drawn to scale: 100 (Author, 2021) LEGEND

B D E F L

3000 litres greywater storage HDPE tank 2500 litres preliminary treatment HDPE tank 2500 litres main treatment HDPE tank 2500 litres first storage HDPE tank 3000 litres second storage tank connected to each WC cisterns on a floor level.

4.4 THE DESIGNED OGTS LAYOUT MOUNTED TO ZETHUSHOF FLATS’ FAÇADE Figures 63 and 64 illustrate the layout of the designed OGTS mounted onto ZF’s façade on elevation and isometric view.

Figure 63: Front view of the full unit of the designed OGTS to scale 1:100 (Author, 2021)

Figure 64: Isometric view of the full unit of the designed OGTS to scale 1:100 (Author, 2021)

4.5 COMPONENTS OF THE DESIGNED OGTS The author recommends a solar photovoltaic system (a sustainable system) via a pulley mechanism to reduce the energy used to pressure a force pump to operate the lift shaft for the recirculation and recycling of greywater in the OGTS. Figure 65 illustrates the entire component of the designed OGTS as proposed by the author.

Gear box connected to 0.25Kw- 220 V- single-phase electric motor to control the motion of the pulley system 0.25Kw- 220 V- single- phase electric motor 50Ah 24v battle born LiFePO4 lithium-ion battery- with built- in BMS -3000-5000 deep cycle rechargeable battery to store solar energy 300W capacity custom made parabolic polycrystalline solar panel modules to store solar energy to the battery to move the pulley

Steel counterweight with 50kg iron bars each to lift the recycling tank with the connected pulley system Steel counterweight rails Elevator hoisting steel wire travelling cable connected to pulley system with emergency breaks 50mm diameter ductile recycling wastewater pipe (outlet) 50mm diameter ductile wastewater pipe (inlet)

3000 litres second storage HDPE tank

3000 litres Greywater storage HDPE tank- for system’s flow rate control

110mm diameter diameter ductile pipe for air vent 2500 litres preliminary treatment HDPE tank 2500 litres main treatment HDPE tank 2500 litres first storage HDPE tank 3000 litres recycling HDPE tank to each floor level

Figure 65: Components of the designed OGTS on isometric view- scale 1:100 (Author, 2021)

The recycling tank is attached to the pulley system and operates with the elevator mechanism (Figure 65). In addition, the pulley system is proposed to have emergency breaks added to the system for safety and the connecting phase of the recycling tank to the first and storage tanks. 4.6 SPECIFICATION OF THE OGTS ADDITION Figure 65 indicates that the recycling phase has to have a mechanical operation as a backup operation system. The author recommends additions to the designed system to aid the system performance. Table 26 shows the specification of the system addition. Table 26: The specification of the system addition- (compiled by the author) Name

Image

0.25Kw- 220 V- Single-phase electric motor Cost: R1, 304. 10 (year- 2021) (Hoist factory, 2021)

300W-capacity custom made parabolic polycrystalline solar panel modules to capture solar energy to the battery storage to move the pulley system (Green prophet, 2020) Elevator hoisting steel wire cable (Alibaba, 2021).

The author recommends that the designed system be controlled and monitored by an employee on a building site. This on-site operator requires a control room to monitor and manage the designed OGTS. The OGTS should be connected to a computer programme for easy switching on and off, specifically when the system is mounted to the fifteenth floor of a building’s facade. The designed OGTS should also be linked to a building’s integrated systems, such as lighting and CCTV systems, so that the OGTS can be easily monitored and managed along with the other systems.

4.7 DIVISION OF THE DESIGNED OGTS TO ZETHUSHOF FLATS’ FLOOR PLAN AND FACADE Due to the large numbers of litres of greywater from each of ZF’s floors (Table 15), the designed OGTS was considered to be split on every five floors and facade into three sections on the ZF’ - floor plan and facade to avoid system overload. The system spilt on the fifth-floor plan and building’s facade are illustrated in Figures 66, 70, and 71. The split treatment allows partial systems distribution, incremental installation, and partial system servicing. The designed OGTS was implemented to treat greywater from four units each of every ZF’s five floors and recycle the treated greywater back to WC cisterns. Figures 66 to 69 illustrate the division of the designed OGTS on the ZF fifth-floor plan per four units each into three sections, on both the building’s horizontal floor plan and its vertical facade. Therefore, according to Figures 70 and 71, the number of designed OGTS units on the ZF’s building facade is a minimum of nine.

UNIT 1

UNIT 2

UNIT 3

1: 100 0

UNIT 5

UNIT 6

10m

15m

UNIT 7

20m

UNIT 8

25m

UNIT 9

Figure 66: Division of the designed ogts to Zethushof ’s 5th-floor plan on scale 1: 100 (Author, 2021)

UNIT 4

NORTH

UNIT 10 UNIT 11 UNIT 12

The ZF floorplan is divided into three sections using colour codes such as red, yellow, and blue. The designed OGTS is mounted along the existing ZF’s duct location illustrated in Figures 67 to 69.

UNIT 1

UNIT 3

UNIT 2

UNIT 4

Figure 67: First section of the system treatment on the Zethushof Flats fifth-floor plan and isometric view to scale 1:100 (Author, 2021)

UNIT 7

UNIT 8

UNIT 6

UNIT 5

Figure 68: Second section of the system treatment on the Zethushof Flats fifth-floor plan and isometric view to scale 1:100 (Author, 2021)

UNIT 9

UNIT 10

UNIT 11

UNIT 12

Figure 69: Third section of the system treatment on the Zethushof Flats fifth-floor plan and isometric view to scale 1:100 (Author, 2021)

4.8 ZETHUSHOF FLAT’S FAÇADE DEVELOPMENT- A RETROFIT The designed OGTS is mounted onto ZF’s facade to retrofit its wastewater system. The retrofit serves as a facade development to ZF (Figure 70) and other apartment buildings in Pretoria. The autonomous movement of the designed OGTS (Figure 72) on ZF also adds to the aesthetics of the building.

Figure 70: The designed OGTS mounted onto the Zethushof Flats’ facade in divisions to scale 1:100, perspective view (Author, 2021)

Figure 71 illustrates a rendered view of the designed OGTS onto ZF’s facade. This facade development enhances the ZF occupants’ experience and interaction with the building.

Figure 71: Rendered view of the designed system onto Zethushof Flats’ façade to scale 1:100, perspective view (Author, 2021)

4.8.1 AUTONOMOUS MOVEMENT OF THE OGTS’ RECYCLING TANK ONTO ZETHUSHOF FLATS’ FAÇADE Figure 72 illustrates the autonomous movement of the recycling tank- designed OGTS.

System connected to final storage tank on first floor

Scenario 1

Scenario 2 LEGEND Recycling tank (2500 litres)

Scenario 3

Counter weight

Figure 72: Autonomous movement of the designed system- recycling tank on elevation view on scale 1:100 (Author, 2021)

4.9

SYSTEM ILLUSTRATION ON THE SELECTED CASE STUDIES URBAN APARTMENT BUILDINGS

Figures 73 and 74 illustrates the designed OGTS onto the selected apartment case studies from Chapter 2, which is the Sharon’s Place (SP) and the Zethushof- Flats (ZF). The figures also illustrate people/ residents interacting with the mounted OGTS on the SP and ZF.

Figure 73: Designed OGTS mounted onto the Sharon’s Place eastern facade (Author, 2021)

Figure 74: Designed OGTS mounted onto the Zethushof Flats southern facade (Author, 2021)

4.10 FINDINGS When designed OGTS are mounted onto apartment buildings in Pretoria (into a split unit as explored in Figures 66 to 69), the bulk volume treatment of wastewater (greywater and blackwater) by sewage treatment plants is reduced, reducing their operational load pressure. In addition, the designed OGTS improves the facade view of most apartment buildings when mounted. 4.11 CONCLUSION This chapter introduces objectives 1.8.5, listed in Chapter 1: •

To design an on-site treatment system design blueprint for adaptation onto diverse urban apartment buildings in Pretoria.

CHAPTER 5- FINDINGS, RECOMMENDATIONS, AND CONCLUSION The study was initiated to achieve the key objectives as listed in chapter 1 and indicated in Table 27. Table 27: No. 1.8.1 1.8.2 1.8.3 1.8.4 1.8.5

5.1

Review of the research objectives from Chapter 1 (compiled by the author) Objectives To explore specific wastewater systems in urban apartment buildings from both international and local case studies. To investigate the wastewater system in ZF through site visits and architectural drawing review. To compare the wastewater system in ZF with best-practice international and local case studies. To design an on-site treatment system design that recycles greywater in urban apartment buildings using ZF through selected data from the literature review. To design an on-site greywater treatment system design blueprint that could be adapted to diverse urban apartment buildings in Pretoria.

SUMMARY OF THE RESEARCH

In relation to the research objectives, sub- problems and hypotheses, the research is summarised as follows. 5.1.1 CHAPTER 1 Chapter 1 introduces the research main problem, research methodology and the research structure. The most pertinent of the research problem settings states that: •

South Africa’s sewage treatment plants are malfunctioning, and this is considered to be due to the bulk treatment of wastewater from urban apartment buildings. 5.1.2 CHAPTER 2

In summary, the literature review introduces key background study relating to the research. The importance and various techniques of retrofitting existing apartment buildings from local and international case studies was defined. The selected apartment case study for the purpose of retrofit (ZF) was investigated through site visits and architectural drawing review. 5.1.3 CHAPTER 3 Chapter 3 focuses on the design development phase of the research. In summary, this chapter breaks down the design process of the designed OGTS from sketch to product phase. The design development phase (2.1 and 2.2) from the research structure is strictly followed to effectively define specific design criteria. The designed OGTS, its cross section perspective and flow diagram was drawn by the author. The components of the designed OGTS is compared with the selected best practices of OGTS to analyse its advantage. 5.1.4 CHAPTER 4 Chapter 4 focuses on the application phase of the designed OGTS to Zethushof Flats’ façade. The designed system was also illustrated onto the selected apartment buildings in Pretoria. In summary, this chapter breaks down the mounting details of the fixed components of the designed OGTS onto Zethushof Flats’ façade. Specific system addition is defined to operate the designed OGTS. Also, the designed OGTS is mounted to split-units onto Zethushof ’s building façade to avoid system overload. 62

5.2 RESEARCH HYPOTHESES / RESEARCH FINDINGS The research hypotheses are summarised against the research findings in Table 28. Table 28: Review of the research hypotheses versus the research findings (compiled by the author) Research hypotheses Research findings -Hypothesis 1It is hypothesised that the wastewater systems in urban apartment buildings in Pretoria are largely similar.

-Hypothesis 3It is hypothesised that by adopting an appropriate system design method of on-site treatment in urban buildings, the sewage treatment plant in Pretoria would reduce the wastewater treatment load. -Hypothesis 4It is hypothesised that wastewater recycling in urban apartment buildings in Pretoria would be enhanced if an appropriate system is designed to adopt on-site treatment system.

-Research finding 1According to the investigation of the ZF and SP buildings in Pretoria, it is deduced that the wastewater systems in urban apartment buildings are largely similar- wastewater to sewage treatment plants to water bodies. -Research finding 3The author designed an on-site greywater treatment system for urban apartment buildings to reduce wastewater treatment loads in municipal sewage treatment plants. The designed system recirculate and recycle greywater for reuse to flush WCs instead of potable water. -Research finding 4The author designed the proposed system to have a visible component to make the process of on-site greywater treatment works visible. The author’s opinion is that implementing the designed system onto urban apartment buildings enhances wastewater recycling in buildings in Pretoria.

5.3 RESEARCH RECOMMENDATIONS The author’s recommendations are the following: •

South Africa National Building Regulations (SANS 10400-XA & XB) should have greywater building codes such as the Leadership in Energy and Environmental Design (LEED) rating in the United States of America to regulate greywater management in buildings. Architects and building-professionals must consult the regulations before buildings are approved for designing and building.

•

The OGTS must be controlled and monitored by an employee on the building site. A control room is required for the designed system. The designed system must be integrated into the management building system for ease-of-use.

•

The didactic concept of the research should enhance awareness of greywater recycling works when implemented onto urban apartment buildings because people would identify and in teract with the fitted buildings and be conscious of their water use and reuse possibilities to improve their water use by changing their habits.

5.4 FUTURE RESEARCH For future research the following should be considered. •

Explore approaches to rainwater harvesting – a sustainable practice in the residential sector, for on-site recycling and management in urban apartment buildings.

•

Explore other renewable energy resources such as wind turbines to generate kinetic energy for operating the pulley system in the OGTS. Wind energy would be an alternate source to the proposed solar photovoltaic panels in the event that the building orientation does not promote the effective capture of solar energy, or during overcast weather.

5.5 RESEARCH CONCLUSION This research serves as a design blueprint to engineers to develop a real-scale model of the designed OGTS. The logical solution to the malfunctioning sewage treatment infrastructure in Pretoria is to fix them or build new treatment plants. However, this research emphasises that having the designed OGTS adapted onto most urban apartment buildings in Pretoria is another solution to the malfunctioning sewage treatment plants in Pretoria. This OGTS results in the recirculation of greywater for flushing WCs so that sewage treatment plants focus on the effective treatment of blackwater.

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