SBR Design Report

Page 1

Sequencing Batch Reactor Design Report AIT Waste Water Treatment System

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Document History Version

Description

Date

Author

Checked

Number

1

Original

27/03/13

i

TS

LM

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Table of Contents Document History............................................................................................................................... i 1.0

Introduction .......................................................................................................................... 1

2.0

Characteristics of the treatment process.............................................................................. 1

2.1

3.0

Treatment Process ................................................................................................................. 1

2.1.1

Fill ............................................................................................................................... 2

2.1.2

React ........................................................................................................................... 2

2.1.3

Settle .......................................................................................................................... 3

2.1.4

Decant ........................................................................................................................ 3

2.1.5

Idle .............................................................................................................................. 3

Treatment system design ...................................................................................................... 3

3.1 Preliminary Treatment .......................................................................................................... 4 3.1.1

Screening Influent Wastewater.................................................................................. 4

3.1.2

Influent-Flow Equalisation ......................................................................................... 4

3.2 SBR Design ............................................................................................................................. 5 3.2.1

Reactor basin .............................................................................................................. 5

3.2.2

Flow-Paced Batch Operation ...................................................................................... 5

3.2.3

Aeration ...................................................................................................................... 5

3.2.4

Decanting ................................................................................................................... 6

3.2.5

Bottom Slope .............................................................................................................. 6

3.3 Post-Basin Effluent Equalisation ........................................................................................... 6 3.4 Parameters to Be Monitored by the SCADA System ............................................................. 6 3.5 Sludge wasting and storage .................................................................................................. 7 4.0

Structural design of the treatment tank ............................................................................... 7

4.1 Equilibrium ............................................................................................................................ 7 4.2 Walls ...................................................................................................................................... 8 4.3 Base design............................................................................................................................ 8

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

List of Figures Figure 1 – SBR treatment cycle........................................................................................................... 2 Figure 2 - Treatment system P&ID…………………………………………………………………………………………………4

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

1.0

Introduction

SBR’s are used all over the world and have been around since the 1920s. With their growing popularity in Europe and China as well as the United States, they are being used successfully to treat both municipal and industrial wastewaters, particularly in areas characterised by low or varying flow patterns.

This type of plant is particularly suited for use on the AIT campus for a number of reasons, including: 

As there is limited space to locate the system, treatment can take place in a single basin, allowing for a smaller footprint. Low total-suspended-solid values of less than 10 milligrams per litre (mg/L) can be achieved consistently through the use of effective decanting that eliminates the need for a separate clarifier.

The treatment cycle can be adjusted to undergo aerobic, anaerobic, and anoxic conditions in order to achieve biological nutrient removal, including nitrification, denitrification, and some phosphorus removal. Biochemical oxygen demand (BOD) levels of less than 5 mg/L can be achieved consistently. Total nitrogen limits of less than 5 mg/L can also be achieved by aerobic conversion of ammonia to nitrates (nitrification) and anoxic conversion of nitrates to nitrogen gas (denitrification) within the same tank. Low phosphorus limits of less than 2 mg/L can be attained by using a combination of biological treatment (anaerobic phosphorus absorbing organisms) and chemical agents (aluminium or iron salts) within the vessel and treatment cycle.

As wastewater discharge permits to the municipal sewer are becoming more stringent, an SBR offers a cost-effective way to achieve lower effluent limits.

2.0

Characteristics of the treatment process

SBRs are a variation of the activated-sludge process. They differ from activated-sludge plants because they combine all of the treatment steps and processes into a single tank, whereas conventional facilities rely on multiple basins. According to a 1999 U.S. EPA report, an SBR is no more than an activated-sludge plant that operates in time rather than space. 2.1

Treatment Process

The operation of the SBR has been based on a fill-and-draw principle, which consists of five steps; fill, react, settle, decant, and idle, as shown in figure 1. These characteristics of each step can be

1

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

altered for differing operational applications which may occur due to AIT’s academic cycle; particularly the significant reduction in discharge during the summer period.

Figure 1 – SBR treatment cycle

2.1.1

Fill

During the fill phase, the basin will receive influent wastewater from the equalisation tank which is discussed in more detail in section 3.1.2. The influent provides food for the microbes in the activated sludge, creating an environment for biochemical reactions to take place. Aeration can be varied during the fill phase to different scenarios, for the AIT SBR an aerated fill system has been selected. Under an aerated-fill scenario, the aeration unit is activated. The contents of the basin will be aerated to convert the anoxic or anaerobic zone over to an aerobic zone. No adjustments to the aerated-fill cycle are needed to reduce organics and achieve nitrification. However, to achieve denitrification, it is necessary to switch the oxygen off to promote anoxic conditions for denitrification. By switching the oxygen on and off during this phase with the diffusers, oxic and anoxic conditions are created, allowing for nitrification and denitrification. Dissolved oxygen (DO) should be monitored during this phase so it does not go over 0.2 mg/L. This ensures that an anoxic condition will occur during the idle phase. 2.1.2

React

This phase will allow for further reduction or "polishing" of wastewater parameters. During this phase, no wastewater shall enter the basin and the aeration unit is on. Because there are no 2

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

additional volume and organic loadings, the rate of organic removal will increase dramatically. Most of the carbonaceous BOD removal will occur in the react phase. Further nitrification will also occur by allowing the aeration to continue. The majority of denitrification will take place in the mixed-fill phase. The phosphorus released during mixed fill, plus some additional phosphorus, will be taken up during the react phase. 2.1.3

Settle

During this phase, activated sludge will be allowed to settle under quiescent conditions; no flow enters the basin and no aeration takes place. The activated sludge tends to settle as a flocculent mass, forming a distinctive interface with the clear supernatant. The sludge mass is known as the sludge blanket. This phase is a critical part of the cycle, as if the solids do not settle rapidly, some sludge may be drawn off during the subsequent decant phase and thereby degrade effluent quality. 2.1.4

Decant

During this phase, a submersible pump will be used to remove the clear supernatant effluent. Once the settle phase is complete, a signal will be sent to initiate the opening of an effluent-discharge valve. The submersible pump will offer the operator flexibility to vary fill and draw volumes. This operation will be optimised by ensuring that the decanted volume is the same as the volume that enters the basin during the fill phase. It is also important that no surface foam or scum is decanted. The vertical distance from the decanter to the bottom of the tank has been maximised to avoid disturbing the settled biomass. 2.1.5

Idle

This step occurs between the decant phase and the fill phase. The time will vary, based on the influent flow rate and the operating strategy. During this phase, a small amount of activated sludge (75 l/cycle), at the bottom of the SBR basin will be pumped out, a process called sludge wasting.

3.0

SBR system design

The SBR treatment system consists of several individual components. The design of the SBR treatment system was completed by TNLS in conjunction with EPS Water, as outlined in the following sections. All pumps, valves, pipe work etc. are to be provided by EPS. A P&ID for the treatment system is shown in figure 2.

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Figure 2 - Treatment system P&ID

3.1 Preliminary Treatment Preliminary treatment includes screening, equalisation and flow monitoring. 3.1.1

Screening Influent Wastewater

Mechanical screens have been incorporated into the design of the SBR to effectively remove debris prior to entering the treatment process. Removing debris from the wastewater stream before it reaches the basins is beneficial to both the treatment process and the settling phase; excess debris is not present to interfere with the solids that need to settle, resulting in a high-quality sludge blanket. Screens also provide protection for the pumps. A mechanical screening system for the plant will be provided by EPS. 3.1.2

Influent-Flow Equalisation

Flow equalisation is critical as there will be significant variations in flow rates and organic mass loadings. As the flow from the AIT’s Engineering Building will be inherently variable, both on a daily and seasonal basis, an equalisation tank were incorporated in the design. The equalisation tank was sized to provide 60m3 of storage, which represents twice the maximum daily flow rate. This will allow sufficient storage of influent in the case of the majority of breakdowns or maintenance issues. The tank was designed with an inclined “V” shaped base and sump containing a submersible pump for ease of cleaning and the removal of settled solids. Submersible pumps for sludge wasting and for the pumping of influent for further treatment will be provided by EPS. Influent-flow equalisation benefits the SBR process in the following ways: 

Allows for a smaller SBR-basin size because it allows for storage until the process cycle is complete.

Allows for storage if the reactor basin must be taken off line for maintenance, or as a result of a breakdown.

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report



Allows for an equal flow volume into the reactor basin, keeping the food to microorganism ratio (F/M) reasonably stable.

3.2 SBR Design 3.2.1

Reactor basin

SBR designs should have a minimum of two basins to allow for redundancy, maintenance, high flows, and seasonal variations. Two basins also allow for redundancy throughout the plant. Due to the relatively low flow rate entering the plant it was found to be unsuitable to provide two dedicated reactors. In order to provide a backup treatment unit, the post basin equalisation tank has been designed similarly to the reactor basin. If the primary reactor is off line, the plant is still able to treat influent wastewater, by bypassing the primary reactor and utilising the post basin equalisation tank as a backup reactor. The biomass from the primary basin will be used to stock the secondary basin. For this to happen, a means of transferring sludge between the two basins must be provided, this will be achieved by means of the wasting pump which can be redirected to the post basin equalisation tank. The reactor was designed to take account of flow rates, influent characteristics, hydraulic retention time, effluent requirements etc.. The design process was completed in accordance with the design process outlined by (Tchobanoglous, et al., 2003). From this process the reactor was sized to be 3.0m x 1.5m x 3.0m with a 0.4m free board. The completed design is provided in appendix A. 3.2.2

Flow-Paced Batch Operation

Flow-paced batch operation has been chosen for the system, this is generally preferable to timepaced batch or continuous flow systems. Under a flow-paced batch system, the reactor receives the same volumetric loading and approximately the same organic loading during every cycle. The SBR basin already has stabilised supernatant in it, which dilutes the batch of incoming influent. 3.2.3

Aeration

Generally the finer the air bubbles used to aerate the waste water the more effective and economical the treatment process. As such fine bubble membrane diffusers have been chosen over coarse-air bubble aeration. Fine-bubble diffusers transfer more oxygen to the water due to increased surface area in contact with water. The same amount of air introduced in a big bubble has less surface area in contact with water than an equal amount of air divided into smaller bubbles. The amount of surface area in contact with water is proportional to the amount of oxygen transferred into water. Depth of aerators also plays a part in oxygen transfer, due to contact time. The deeper the aerator, the longer it takes for the bubble to come to the surface. The fine bubble membrane 5

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

diffusers will be supplied by EPS, they will also supply blowers to supply air to the diffusers. As previously mentioned the post basin equalisation tank will act as a standby reactor, as such it will also be supplied with an aeration unit. 3.2.4

Decanting

During the decant phase, operating under a flow-paced batch operation, 60% of the volume contained in the basin (i.e., the tank contents) will be decanted each time in order to prevent disturbance of the sludge blanket. The decant phase should not interfere with the settled sludge, and submersible pumps should avoid vortexing and taking in floatables. For the plant to run optimally, it is important that the decant volume is the same as the volume added during the fill phase. 3.2.5

Bottom Slope

As with the equalisation tank a sloped bottom with a sump has been provided for the purpose of sludge wasting and for routine tank maintenance and ease of cleaning.

3.3 Post-Basin Effluent Equalisation Post-basin effluent equalisation soothes out flow variations prior to downstream processes. By providing storage and a controllable flow, a more economical downstream sewer system could be deigned. This was possible as the flow from the basin is metered out and does not hydraulically surge the downstream processes. The equalisation tank was provided which will receive effluent from the reactor. Effluent equalisation also ensures that there are not large variations in operating ranges. The tank was sized to hold one decantable volume of the reactor. The tank was also designed similar to the primary reactor with an aeration system, sloped bottom with a sump and submersible pump for sludge removal.

3.4 Parameters to Be Monitored by the SCADA System SCADA is a computer-monitored alarm, response, control, and data acquisition system used by operators to monitor and adjust treatment processes and facilities. Oxidation reduction potential (ORP), dissolved oxygen (DO), pH, and alkalinity are parameters that should be monitored by the Supervisory Control and Data Acquisition (SCADA) system. Manufacturers determine what parameters can be monitored and controlled by the SCADA system. Alkalinity monitoring and addition ensures that a pH of less than 7.0 does not occur. Nitrification consumes alkalinity, and with a drop in alkalinity, pH also drops. If the plant has adequate alkalinity, pH does not change, so it does not need to be raised. Monitoring of certain parameters is important, and the ability to adjust these parameters from a remote location is ideal. The operator needs to be 6

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

able to add chemicals to raise the alkalinity and subsequently the pH. The set point should be an alkalinity value rather than pH based. The operator should have the ability to fully control (i.e., modify) the plant-operating parameters, such as (but not limited to) cycle times, volumes, and set points. The SCADA system will be installed and commissioned by EPS.

3.5 Sludge wasting and storage Sludge wasting will occur during the idle cycle to provide the highest concentration of mixed liquor suspended solids (MLSS). The plant will operate on kg of MLSS and not concentration. Sludge from the SBR basin will be wasted to a pre-cast storage tank, with storage for over 28 days (9m3). The sludge-holding-tank capacity was based on approximate sludge characteristics, see appendix A. A high-level alarm and interlock will be provided to prevent sludge-waste pumps from operating during high-level conditions in the holding tanks. Controls will also be provided to prevent overflow of sludge from the holding tank. The sludge holding tank will consist of a steel fibre reinforced precast concrete unit with an approximate footprint of 2.6m x 2.6m, supplied by Shay Murtagh Precast.

4.0

Structural design of the treatment tank

The SBR was designed to be housed within a single reinforced concrete tank with interior dividing walls to create individual tanks. The SBR system was also designed to be located entirely below ground level. This layout was select for several reasons, firstly due to restrictions regarding available space. By incorporating all treatment processes within a single unit the area requirements of the system were greatly reduced. Also due to the nature of the institute minimal aesthetical impacts were desirable as such by locating the system below ground level the visual impact was also greatly reduced.

4.1 Equilibrium In order to ensure the stability of the completed works the tank design was checked to ensure that uplift would not occur. Due to the paucity of geotechnical information for the SBR location it was assumed that the water table can rise to the surface. Uplift checks were completed in accordance with EC-7 and the base of the tank was sized accordingly to ensure uplift was not possible. In order to eliminate the possibility of uplift for the worst case scenario a base thickness 0.6m was found to be necessary. See Appendix B for complete uplift calculations.

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

4.2 Walls The exterior walls of the tank were analysed as retaining walls, as maximum stress will occur when the tank empty and acting as an earth retaining structure. The design was completed in accordance with EC-2. As stresses placed upon interior walls, including the worst case scenario, will be of a lesser magnitude than that of the exterior wall similar reinforcing will be applied in those elements. The completed structural design is supplied in Appendix C, and the associated bar schedule is supplied in appendix D.

4.3 Base design Similarly to the design of the walls of the tank the base was designed in accordance with EC-2 assuming the worst case scenario. The base was analysed as a one way spanning slab supported by the side walls of the tank and loading was in the form of upward earth pressure. Upon completion of the analysis it was found that minimum reinforcement governed. The base section was also analysed for shear and was found not to require shear reinforcement. The section was also checked for crack control, given the exposure class of the concrete and resulting minimum reinforcement the design was found to be adequate. The section was also found to be adequate in relation deflection. The completed structural design is supplied in Appendix C, and the associated bar schedule is supplied in appendix D.

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Sponsor Acceptance

Approved by the Project Sponsor:

____________________________________________

Project Sponsor: AIT

9

Date: _____________________

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Appendix A: SBR Design

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR Design Drawing Ref:

Calculations By:

009

Reference

TS

1 Checked By: NMcH

Calculations

of

Date 19/03/13

Output

Primary data Occupant No. Flow (liters/day/person) BOD5 (grams/person/day) BOD5 (mg/l)

500 60 20 333

HYDRAULICS Influent flow rate: Q = No. occupants x Flow = 500 x 60 = 30000 l/day Q = 30m3/day

= 30 m3/day

Peak flow: Daily flow Q through system assumed to occur between 9am and 6pm. Time (T) = 9 hours Peak flow factor =3.

Ts = 9 x 3600 = 32400 seconds

q= =

đ?‘„ đ?‘Ľ 1000 Ă— đ?‘‡đ?‘ 30 đ?‘Ľ 1000 32400

3

đ?‘Ľ3 Q = 2.78 l/s

= 2.78 l/s

11

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR Design Drawing Ref:

Calculations By:

009

Reference

TS

2 Checked By: NMcH

Calculations

of

Date 19/03/13

Output

SYSTEM SIZING Hydraulic Retention Time (HRT) = 6 hours Reactor Decant Rate (R) = 60% Inner tank dimensions: Width (W) = 3.0 m Depth (D)= 3.0 m Free board (FB) = 0.4 m

Equalisation tank to provide minimum 24 hours storage.

Ve = 60m3

Equalisation tank Ve = Q x 2 = 30 x 2 = 60 m3

Dimensions: 7.0 x 3.0 x 3.0

Equalisation tank length =

đ?‘‰đ?‘’ đ?‘Šđ?‘Ľđ??ˇ 60

= 3.0 đ?‘Ľ 3.0 = 6.667 m

1 No. Primary aeration basin to be provided. Post basin equalisation tank to be designed to act as a standby reaction basin.

Batch Volume =

� 24/�

Vr = 12.5m3

30

=24/6 =7.5 m3 đ?‘„

đ?‘…

Aeriation Basin Vr = 24áđ??ťđ?‘…đ?‘‡ á 100 30

60

= 24á6 á 100 12 = 12.5 m3

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR Design Drawing Ref:

Calculations By:

009

Reference

3 Checked By:

TS

NMcH

Calculations

of

7

Date 19/03/13

Output

đ?‘‰đ?‘&#x;

Aeration Basin length = 3.2 đ?‘Ľ 3

Dimensions:

12.5 = 3.0 đ?‘Ľ 3.0

1.5 x 3.0 x 3.0

= 1.389 m

Vp = 12.5m3 Post basin equalisation tank Vp = 12.5 m3

Post basin equalisation tank length =

đ?‘‰đ?‘? 3.2 đ?‘Ľ 3 12.5

= 3.0 đ?‘Ľ 3.0 = 1.389 m

13

Dimensions: 1.5 x 3.0 x 3.0

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR Design Drawing Ref:

Calculations By:

009

Reference

TS

4 Checked By: NMcH

Calculations

Treatment Parameters Value

Wastewater temperature Influent BOD5 for each day Hydraulic detention time, θ Food-to-microorganism ratio, FM Kinetic coefficients: Biomass yield, Y Endogenous decay coefficient, kd Average concentration of settled sludge, C Settled sludge specific gravity, G Percent of the reactor volume which will be decanted, Dr Liquid depth of SBR Sludge wasting per day Percent of biodegradable in effluent

Reactor

=

đ?‘†đ?‘†đ?‘–đ?‘› đ?‘Ľ đ?‘‰đ?‘&#x; đ?‘‰ đ?‘Ľ đ??šđ?‘€ 250 đ?‘Ľ 7500 7500 đ?‘Ľ 0.1

= 2500 mg/l

MLSS = (SS –VSS)

đ?‘€đ??żđ?‘‰đ?‘†đ?‘† 0.8

= (250 –200)

2500 0.8

= 3175 mg/l

VSStotal =

Date 19/03/13

Output

Parameter Effluent BOD5 Reactor Volume Influent suspended solids, SS Influent volatile suspended solids, VSS

MLVSS =

of

đ?‘€đ??żđ?‘‰đ?‘†đ?‘† đ?‘Ľ đ?‘‰đ?‘&#x; 10đ??¸6

2500 đ?‘Ľ 7500 10đ??¸6

= 18.75 kg

14

Unit 25 mg/l 7500 l/d 250 mg/l 200 mg/l 10 oc 250 mg/l 6h 0.1 MLVSS/MLSS 0.65 kg/kg 0.05 d-1 8000 mg/l 1.02 60 % 2.6 m As required 80 %

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR Design Drawing Ref:

Calculations By:

009

Reference

5 Checked By:

TS

NMcH

Calculations

SStotal =

of

7

Date 19/03/13

Output

đ?‘€đ??żđ?‘†đ?‘† đ?‘Ľ đ?‘‰đ?‘&#x; 10đ??¸6

=

3175 đ?‘Ľ 7500 10đ??¸6

= 23.813 kg

Reactor Sludge Storage S = (SStotal x 10E6)/(C x G x 1000) = (23.813 x 10E6)/(8000 x 1.02 x 1000)

Reactor

sludge

storage = 2.918m3

= 2.918 m3 �

Sludge Depth = đ??´đ?‘&#x;đ?‘’đ?‘Ž =

2.918 3.0 đ?‘Ľ 1.5

= 0.648 m

Liquid Depth, d = D – FB = 3.0 – 0.4 = 2.6 m

Liquid Depth Following Decant = 2.4 – (d x Dr) = 2.4 – (2.6 x 0.6) = 0.84 m Reactor Sludge Depth < Liquid Depth Following Decant

15

adequately sized

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR Design Drawing Ref:

Calculations By:

009

Reference

6 Checked By:

TS

NMcH

Calculations

of

7

Date 19/03/13

Output

SLUDGE PRODUCTION

Following calculations per 7.5m3 batch

Volitile Solids Px = (Y x (SS – VSS) x Vr) –

(đ??žđ?‘‘ đ?‘Ľ đ?‘€đ??żđ?‘‰đ?‘†đ?‘†) 10đ??¸6

= (0.65 x (250 – 200) x 7500) –

(0.5 đ?‘Ľ 2500 10đ??¸6

= 0.244 kg

Inert Solids SSi = (SS – VSS) x Vr = (250 – 200) x 7500 = 0.350 kg

Total solids produced SSt = SSi + Px = 0.350 + 0.244 = 0.594 kg

Sludge Produced S = =

đ?‘†đ?‘†đ?‘Ą đ?‘Ľ 10đ??¸6 đ??śđ?‘Ľđ??ş 0.594 đ?‘Ľ 10đ??¸6 8000 đ?‘Ľ 1.02

Sludge produced per batch = 73l

= 73 l

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR Design Drawing Ref:

Calculations By:

009

Reference

TS

Calculations

Monthly Sludge Storage = =

7 Checked By: NMcH

of

7

Date 19/03/13

Output

� � 4 � 7 � 4.33 1000 73 � 4 � 7 � 4.33 1000

= 8.832 m3

Provide 9000m3 sludge holding tank

Monthly

Sludge

Storage = 9000m3

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Appendix B: Uplift Check

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR uplift check Drawing Ref:

Calculations By: TS

Reference

Calculations

Tank length, B = 11.2 m Tank depth, H = 3.0 m Tank width, W = 3.6 m Wall thickness, t = 0.3m 2 No. internal walls Concrete Lid to cover tank 0.2 m thick Assume base depth, D = 0.6m

Soil Parameters C,k = 0 ∅’k = 30 Îł = 22 Kn/m3

ULS DESIGN đ?‘‰đ?‘‘đ?‘ đ?‘Ą,đ?‘‘ ≤ đ??şđ?‘ đ?‘Ąđ?‘?,đ?‘‘ + đ?‘…đ?‘‘

DESTABILISING VERTICLE ACTION đ?‘‰đ?‘‘đ?‘ đ?‘Ą,đ?‘‘ ≤ đ??şđ?‘‘đ?‘ đ?‘Ą,đ?‘‘ = đ?›žđ??ş,đ?‘‘đ?‘ đ?‘Ą đ?›žđ?‘¤ (đ??ť + đ??ˇ) đ??ľ EC – 7 Table A.15

Checked By: NMH

of

Date 21/03/13 Output

Tank Data

EC – 7 Eq. 2.8

1

= 1.0 x 9.81 x (3.0 + 0.6) 11.2 = 384.6 Kn/m

19

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AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR uplift check Drawing Ref:

Calculations By: TS

Reference

2 Checked By: NMH

Calculations

đ??şđ?‘ đ?‘Ąđ?‘?,đ?‘‘ = đ?›žđ??ş,đ?‘ đ?‘Ąđ?‘? (đ?›žđ?‘?,đ?‘˜ (4 đ?‘Ą đ??ť + đ??ľ đ??ˇ + đ??ľ đ?‘Ąđ?‘™ +

2 đ?‘Ľ (đ??ľ(đ??ť + đ??ˇ)đ?‘Ľđ?‘Ą) )) đ?‘Š

= 0.9 (24(4 x 0.3 x 3.0 + 11.2 x 0.5 + 11.2 x 0.2 +

2(11.2(3.0+0.5)0.3 )) 3.2

= 405.9 Kn/m

Additional resistance between soil and tank side walls must be calculated đ?‘…đ?‘˜ = 2 (đ??ť + đ??ˇ)đ??ž đ?œŽđ?‘Łâ€˛ tan đ?›ż đ?œŽđ?‘Łâ€˛ = 0.5 (đ??ť + đ??ˇ)(đ?›ž − đ?›žđ?‘¤ ) = 0.5 (3.0 + 0.5)(22 − 9.81) = 21.3 Kn/m2 2

đ?›ż ′ = 3 (âˆ…â€˛đ??ž ) 2

= 3 (30) = 20o

EC – 7 Table C.1.1

Date 21/03/13 Output

STABILISING VERTICAL ACTION EC – 7 Table A.15

of

K = 0.29 đ?‘…đ?‘˜ = 2 (3.0 + 0.5)0.29 đ?‘Ľ 21.3 đ?‘Ľ tan 20 = 15.7 Kn/m

20

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Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

SBR uplift check Drawing Ref:

Calculations By: TS

Reference

3 Checked By:

of

3

Date

NMH

21/03/13

Calculations

Output

đ?‘…đ?‘‘ = 2 (đ??ť + đ??ˇ)đ??žđ?‘‘ đ?œŽđ?‘Łâ€˛ tan đ?›żđ?‘‘′ tan âˆ…â€˛đ?‘˜ ) đ?›žđ?‘š

âˆ…â€˛đ?‘‘ = đ?‘Ąđ?‘Žđ?‘›âˆ’1 (

tan 30 ) 1.25

= đ?‘Ąđ?‘Žđ?‘›âˆ’1 ( = 24.8o 2

đ?›żđ?‘‘′ = 3 (âˆ…â€˛đ?‘‘ ) 2

= 3 (24.8) = 16.5o EC – 7 Table C.1.1

Kd = 0.5 đ?‘…đ?‘‘ = 2 (3.0 + 0.5)0.5 đ?‘Ľ21.3 đ?‘Ľ tan 16.5 = 22.1 Kn/m đ?‘…

đ?‘…đ?‘‘ = đ?›ž đ?‘˜

đ?‘š

15.7

= 1.25

= 12.6 Kn/m đ?‘‰đ?‘‘đ?‘ đ?‘Ą,đ?‘‘ ≤ đ??şđ?‘ đ?‘Ąđ?‘?,đ?‘‘ + đ?‘…đ?‘‘ 384.6 ≤ 405.9 + 12.6

Adequate

384.6 ≤ 418.5

uplift

21

to

resist

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Appendix C: Structural Design

22

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

Concrete Tank Drawing Ref: 010 Reference

Calculations By: TS

1 Checked By: NMH

Calculations

21/03/13 Output

Tank Data Tank length, B = 11.2 m Tank depth, H = 3.0 m Tank width, W = 3.6 m Base depth, D = 0.6m Wall thickness, t = 0.3m 2 No. internal walls Concrete Lid to cover tank 0.2 m thick Soil Parameters C,k = 0 ∅’k = 30 γ = 22 Kn/m3 Ka = 0.5 ABP = 300 kN/m2 Materrial Properties fck = 50 N/mm2 fct,eff = -4 N/mm2 fyk = 500 N/mm2 Ep = 200 kN/mm2 Ecm = 37.3 kN/mm2 National Annex Based Factors G,sup SW = 1.35, Partial factor for unfavourable self-weight – ULS G,inf SW = 1.0 Partial factor for favourable self-weight – ULS Q,sup live = 1.5 Partial factor for unfavourable live loads – ULS cc = 0.85 Compressive strength factor c = 1.5 Partial factor for concrete (for ULS) s = 1.15 Partial factor for rebar (for ULS)

EXPOSURE CLASS AND DURABILITY REQUIREMENTS Exposure class = XD3 BS-8005

of

Date

Minimum concrete cover to rebar = 45 mm Allowable crack width = 0.30 mm

23

8

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

Concrete Tank Stability Check Drawing Ref: 010 Reference

Calculations By: TS

Checked By: NMH

2

8

of

Date 23/03/13

Calculations

Output

HORIZONTAL FORCE pa = KaĎ gh = 0.26 x 2200 x 10-3 x 9.81 x 3.6 = 20.2 Kn/m2

Allowing for the minimum required surcharge of 10 kN/m2, and additional horizontal pressure of:

ps = 0.26 x 10 = 2.6 kN/m2 Hk(earth)

= 36.40

kN

Hk(earth) = 0.5 pah = 0.5 x 20.2 x 3.6 = 36.40 kN

Hk(Sur) = 11.88 kN

Hk(sur) = psh = 3.3 x 3.6 = 11.88 kN

VERTICAL LOADS Permanent Loads: Wall = 0.3 x 3.0 x 24 Base = 0.6 x 1.8 x 24 Lid = 0.2 x 1.8 x 24 Total

= 21.6 kN/m = 25.9 kN/m = 8.6 kN/m = 56.1 kN/m

Variable Loads Effluent = 1.5 x 2.6 x 9.81 = 45.9 kN/m

24

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

Concrete Tank Wall Design Drawing Ref: 010 Reference

Calculations By: TS

Checked By: NMH

Calculations

3

of

Date 23/03/13 Output

BEARING PRESSURES AT THE ULTIMATE LIMIT STATE

Consider load combination 1 as the critical combination

p = N/D +/- 6M/D2

M = γf (Hk(earth) x arm) + γf (Hk(surcharge) x arm) + γf (wall x arm) + γf (Effluent x arm) = 1.35 (36.4 x 3.6/3) + 1.5 (16.2 x 3.6/2) + 1.35 (21.6 x 0.75) + 1.5 (45.9 x 0.15) = 59.0 + 43.7 + 21.9 + 10.3 = 134.9 kN m

Therefore bearing pressure at centre of tank: P = (1.35 x (21.6 + 25.9 + 8.6) )/1.8 +/- (6 x 134.9)/1.82 = 42.1 +/- 249.8 = 291.9, -207.7 kN/m2

P = 291.9, -207.7 kN/m2

291.9 < 300 kN/m2 therefore passes bearing check

25

8

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

Concrete Tank Wall Design Drawing Ref: 010 Reference

Calculations By: TS

Checked By: NMH

Calculations

4

of

8

Date 23/03/13 Output

BENDING REINFORCEMENT Wall: Horizontal force = Îłf 0.5 KaĎ gh2 + Îłf psh = 1.35 x 0.5 x 0.26 x 2200 x 10-3 x 9.81 x 3.02 + 1.50 x 2.6 x 3.0 = 34.1 + 11.7 = 45.8 Kn Considering the effective span, the maximum moment is: MEd = 34.1 x (0.3 + 3.0/3) + 11.7 x (0.3 + 3.0/2) = 65.4 kNm

MEd/bd2fck =

65.4 đ?‘Ľ106 1000 đ?‘Ľ 2452 đ?‘Ľ 50

= .022 Therefore la = 0.95 65.4 đ?‘Ľ106

As = 0.95 đ?‘Ľ 245 đ?‘Ľ .87 đ?‘Ľ 500 = 646 mm2/m Provide H16 bars at 225 mm centres (As(Prov) = 894 mm2/m)

As(Prov) = 894 mm2/m

The minimum area for inner and transverse wall reinforcement is given by: As = 0.15btd/100 = 0.0015 x 1000 x 245 = 368 mm2 Provide H12 bars at 225 mm centres (As = 393 mm2/m), bottom and distribution steel

26

As(Prov) = 393 mm2/m

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

Concrete Tank Base Design Drawing Ref: 010 Reference

Calculations By: TS

Checked By: NMH

Calculations

5

of

8

Date 23/03/13 Output

BASE Vertical Loads: Permanent Loads: Base = 0.6 x 3.6 x 24 = 51.8 kN Variable Loads Effluent = 3.0 x 2.6 x 9.81 = 76.5 kN Ground Water = 9.81 x 3.6 x 3.6 = -127.1 kN

MEd = (1.0(51.8) + 1.0 (76.5)) 3.6 / 4 = 115.5 kN m MEd = (1.0(51.8) - 1.5 (127.1)) 3.6 / 4 = -125.0 kN m

MEd/bd2fck =

125.0 đ?‘Ľ106 1000 đ?‘Ľ 5452 đ?‘Ľ 50

= 0.008 Therefore la = 0.95 125.0đ?‘Ľ106

As,req = 0.95 đ?‘Ľ 545 đ?‘Ľ .87 đ?‘Ľ 500 = 555 mm2/m

The minimum area for steel and longitudinal distribution steel which is required in base is given by: As = 0.15btd/100 = 0.0015 x 1000 x 545 = 818 mm2 Provide H16 bars at 225 mm centres (As = 894 mm2/m), all directions

27

As(Prov) = 894 mm2/m

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

Concrete Tank Base Design Drawing Ref: 010 Reference

Calculations By: TS

Checked By: NMH

Calculations

6

of

Date 23/03/13 Output

Base Shear VEd = 37.7 kN VRd,c = [CRd,ck(100Ď lfck)1/3+k1Ďƒcp]bwd 200 đ?‘‘

K=1+√

≤ 2.0

200

= 1 + √600 = 1 + 0.58 = 1.58 đ??´

Ď l = đ?‘? đ?‘ đ?‘–đ?‘‘ ≤ 0.02 đ?‘¤

818

= 1000 đ?‘Ľ 600 = .0014 Ďƒcp = =

đ?‘ đ??¸đ?‘‘ ≤ 0.2 fcd đ??´đ?‘? 138.9đ??¸3 ≤ 0.2 1000 đ?‘Ľ 600

x 50

= .232 ≤ 10 0.18 đ?›žđ?‘? 0.18 = 1.5

CRd,c =

= 0.12 Kl = 0.15 VRd,c = [0.12 x 1.58(100 x 0.0014 x 50)1/3+ 0.15 x 0.232]1000 x 600 = 238’495 N = 238 kN VEd < VRd,c No shear reinforcement required

28

VEd < VRd,c

8

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

Concrete Tank Base Design Drawing Ref: 010 Reference

Calculations By: TS

Checked By: NMH

Calculations

For exposure class XD3 wmax = 0.3 mm

As,minĎƒs = kc k fct,eff Act

BS EN 1992-1-1 7.3.2 (2)

For pure bending kc = 0.4 K = 0.79 fct,eff = fctm = 0.3fck2/3 = 0.3 x 502/3 = 4.1 N/mm2 Act = =

đ?‘?â„Ž 2 1000 đ?‘Ľ 600 2

= 300’000 mm2 Ďƒs= fyk = 500 N/mm2 As,min,c = 0.4 x 0.79 x 4.1 x 300’000/500 = 777 mm2/m

BS EN 1992-1-1 7.4.2 (2)

As,prov > As,min,c Therefore no additional steel required for crack control Deflection đ?œŒ0 đ?œŒ

=

đ?‘?đ?‘‘√đ?‘“đ?‘?đ?‘˜ đ??´đ?‘ ,đ?‘&#x;đ?‘’đ?‘ž

=

1000 đ?‘Ľ 600√50 738

of 23/03/13 Output

Base Cracking BS EN 1992-1-1 T 7.1N

7 Date

x 10-3 x 10-3

= 5.7

29

8

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Project

Revision

AIT Wastewater Treatment System Part of Structure

Calculation Sheet No.

Concrete Tank Base Design Drawing Ref: 010 Reference

Calculations By: TS

Checked By: NMH

Calculations

values of Ď 0/Ď > 1.0 is given by đ?œŒ0 đ?œŒ

đ?œŒ0 đ?œŒ

+ 3.2 √đ?‘“đ?‘?đ?‘˜ (

− 1)3/2]

= 1.3 x [11 + 1.5 √50 x 5.7 + 3.2 √50 x (5.7 - 1)3/2 ] = 393 This value should be multiplied by 310/Ďƒs where the reinforcement stress under the characteristic load is given approximately by: 500

310/Ďƒs = đ?‘“đ?‘Śđ?‘˜ đ??´đ?‘ ,đ?‘&#x;đ?‘’đ?‘ž đ??´đ?‘ ,đ?‘?đ?‘&#x;đ?‘œđ?‘Ł

=

of 23/03/13 Output

The 'uncorrected' value of the limiting span/effective depth ratio, for

(l/d)0 = đ??ž[11 + 1.5√đ?‘“đ?‘?đ?‘˜

8 Date

500

500 đ?‘Ľ 738 818

= 1.11 (l/d)lim = 393 x 1.1 = 432 3600

(l/d)act = 600 =6

Therefore section is adequate to meet deflection requirements

30

8

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

Appendix D: Bar Schedule

31

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

TNLS Consulting Engineers

Drawing ref :

Site ref :

AIT

Date prepared :

Job :

Waste Water Treatment System

Prepared by :

Member

Bar Mark

Type and size type size

Wall

01 02 03 04 05 06 07 08 09 10 11 12

H H H H H H H H H H H H

16 12 16 16 16 16 16 10 10 10 10 16

No. of mbrs

No. of bars in each

Total no.

1 1 1 1 1 1 1 1 1 1 1 1

50 132 32 14 14 14 50 32 32 28 56 14

50 132 32 14 14 14 50 32 32 28 56 14

B

24-Mar-13

TS

Length of each bar †mm

Shape code

10825 3750 9050 10425 7950 4725 4300 12000 4300 10625 5125 850

41 23 12 23 41 23 21 21 21 21 21 00

Checked by :

B*

C*

D*

E/R *

mm

mm

mm

mm

mm

3510 560

3510

210

3015 1625 1545 420 475 420 1770 1770

210 3015

210

210 3510 210 3010 3510 5555 420 7045 210 3015 210 3015 420 3510 475 11080 420 3480 1770 7115 1770 1615 840

†Specified in multiples of 25mm.

32

NMH

A*

This schedule conforms to BS 8666:2005 * Specified in multiples of 5mm.

Rev:

010

Rev letter

A A A A A A A A A A A

B

AIT Waste Water Treatment Facility: Sequencing Batch Reactor Design Report

33

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