An eco-machine in an urban landscape: A feasibility study
Prescott College
Spring 2014
Authors Aharon, Shann
saharon@prescott.edu shannaharon@gmail.com (401) 241-0709
Frisch, Jeffrey
jeffrey.frisch@prescott.edu jeff.frisch.jr@gmail.com (585) 429-0160
This document has been compiled as part of a culminating senior project for both authors.
The authors thank the following individuals for their guidance throughout the design process: Kristen Densmore, William Otwell, David Hanna, and Antony Brown.
Contents Introduction Technological and Biological Metabolisms
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Milagro Arts Center 2 Stages of Wastewater Treatment
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Biologically-Based Secondary Treatment Options 5
Design Major Impulses 10 Eco-Machine Mechanics 12 Project Phasing 15 Legal Considerations and Water Quality
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Case Studies 19
Concluding Thoughts 24 Appendix 26
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Introduction
n the dominant societal paradigm, the flow of resources and materials is a linear cradle-to-grave progression. From this mentality, the human-created concept of waste has emerged. Materials have a determined lifespan extending from extraction through consumption to disposal. Our planet is of finite size and resources. Only solar energy enters its boundaries (save for the occasional meteorite) and only reemitted radiation escapes. There is no “away”.
Technological and Biological Metabolisms All processes on Earth involve materials that are part of what McDonough and Braungart distighuish as either the biological metabolism or the technical metabolism3. Biological nutrients move in and out of biological cycles – decomposition by microorganisms followed by incorporation into other organic matter. Technical nutrients are materials, such as metals and petrochemicals, which are a part of industrial processes. Products, such as computers or televisions, are composed entirely of technical nutrients. Maintaining a separation between the metabolisms allows the technical nutrients to maintain a high quality and the ability to be reused in a similar product. When biological and technical nutrients are combined in a product, the result is what McDonough and Braungart call a, “monstrous hybrid”. In such a product, the
technical and biological nutrients are nearly impossible to separate, rendering the biological nutrients too toxic to reenter the biological metabolism, while the technical nutrients are of reduced quality and destined to downcycling or outright disposal. The lifespan of wastewater constituents is an example of a cradle-to-grave progression. Biological nutrients, such as phosphate and nitrogen, are extracted from geologic formations and the atmosphere, respectively. As part of fertilizers, these nutrients provide the basis of modern food production1,5. Modern agricultural techniques induce erosion of nutrient-rich top soils, which in turn, require additional application of synthetic fertilizers; a positive feedback loop with a disastrous future1,5. After being consumed as food, these nutrients nourish our bodies, and what is not metabolized passes through. Nutrients are excreted into purified water and flushed “away” only to be separated into sludge or converted into inert substances by specific strains of microorganisms. The effluent is then often treated with a chlorine solution and either evaporates or is discharged into the groundwater supply2. In a pre-industrial world, this process would be relatively benign, as the biological nutrients are recovered and can reenter the biosphere. Unfortunately, technical nutrients are major constituents of modern wastewater. The ever-accumulating sludge at wastewater treatment plants is a monstrous hybrid; too toxic to be used as fertilizer and too contaminated with organic materials to reenter the technosphere.
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Wastewater treatment systems that are based on ecological principles work to interrupt the linear flow of biologically valuable nutrients. By placing a series of small ecosystems at the beginning of the effluent flow, trapped nutrients support primary producers. This creates habitat for microorganisms, macro invertebrates, and potentially amphibian and bird species; these systems clean the effluent to the point where it can safely reenter the biosphere. Additionally, these ecosystems create an aesthetically pleasing, educational aspect of a building. Through implementation of this type of design, a building can imitate a natural system, such as a tree, by harnessing solar energy and filtering water. A building can be transformed from a system that degrades its environment into an ecological asset. While investigating of the possibilities of designing an eco-machine somewhere in Prescott, Arizona, we discovered that an up-and-coming arts center was interested in this type of technology.
Milagro Arts Center Milagro Arts Center is located at 126 North Marina Street in Prescott, Arizona. It is proximal to the downtown commercial district; all of the adjacent buildings house, at least in part, commercial enterprises. The overall purpose of the Milagro Arts Center is to “provide space for education in the visual arts, including ceramics, glass blowing, photography, drawing, painting, and print making”4. Members will pay a monthy fee in order to access to the center’s facilities, it has been referenced as an “art gym”. Additionally, the building will have spaces for audio recording, offices, and community gathering. The founders and owners of Milagro Arts Center are local artists and entrepreneurs, Kristen Densmore and Ty Fitzmorris. Constructed in 1935, the building was originally a church. Large, roughly hewn granite blocks compose its outer walls, giving the building a strong and historical presence in the area. The interior was rehabilitated in 1983, which transformed the church into an executive office center. In the construction of the Milagro Arts Center, some elements of the 1983 renovation, such as the second story spaces, will remain. The original windows, historic ceilings, and moldings will also be retained. Environmentally conscious design is a high priority for those involved in the ownership, renovation, and operations of the Milagro Arts Center. The manifestation of ecologically minded ideals in the renovation process includes the following4: • A durable, long-lasting, and upcyclable metal roof has been installed. The new
roofing material will allow for catchment of 95% of rainwater for use in operating dual-flush toilets and in ceramic processes. Rainwater will be stored in a cistern with a capacity of approximately 20,000 gallons.
• A 22kW capacity photovoltaic system has been installed on the roof. This sys-
tem will provide most of the electricity requirements of the building.
• Sky lights have been installed to provide the building with day lighting. This
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will conserve overall electricity needs. • The thermal efficiency of the building will be upgraded with spray foam in-
sulation in the roof, reglazed windows, and a highly efficient heating/cooling system.
• A newly designed kiln shed will be constructed at the rear end of the property
using local adobe blocks.
• Lumber and other materials from demolished structures within the building
will be repurposed as often as possible.
An on-site eco-machine will bolster the already established ecological-effectiveness of the building. In large part, the educational opportunities provided by experimental technologies, such as an eco-machine, make Milagro Arts Center a showcase for the integration of the arts and ecological design in the City of Prescott. References 1. Charles, Dan. 2013. Fertilized world: A mixed blessing. National Geographic: Washington (DC). 2. [EPA] Environmental Protection Agency. 2004. Primer for municipal wastewater treatment systems. Office of Water (EPA): Washington (DC). 3. McDonough, W., and M. Braungart. 2002. Cradle to cradle: Remaking the way we make things. North Point Press: New York (NY). 4. Otwell, William. Milagro Arts Center: Project overview. Unpublished document as part of a personal communication from William Otwell. Otwell Associates Architects: Prescott (AZ) 5. Pearce, Fred. 2011. Phosphate: A critical resource misused and now running low. Yale Environment 360: Yale School of Forestry and Environmental Studies. New Haven (CT).
Stages of Wastewater Treatment Whether in a conventional centralized wastewater treatment facility, or in a small onsite system, wastewater effluent must proceed through a series of treatment stages in order to safely reenter the environment. In alternative systems, the following stages of effluent treatment may occur simultaneously rather than in isolation from each other. Specifically, processes involved in secondary and tertiary treatment are often combined in eco-machines or constructed wetlands. The following is the progression of wastewater through a typical centralized treatment facility:
Primary Treatment
Primary treatment is the initial stage encountered by raw sewage. Essentially, this stage is simply removing and settling out solids from the water. In large, centralized systems, the removal of debris, such as rags, bottles, plastic bags, is an important aspect of primary treatment. Additionally, organic solids and inorganic solids, such as fecal matter and
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sand, settle out. The effluent from primary treatment is far less turbid than the influent; biological oxygen demand (BOD) is reduced by 20-30% and total suspended solids (TSS) are reduced by 50-60% simply through the process of sedimentation2. During this stage, solids settle and become primary sludge, which, in conventional systems, is dehydrated and incinerated or disposed of in a landfill. Additionally, some anaerobic digestion occurs during primary treatment.
Secondary Treatment
Secondary treatment is where the majority of biological processes are employed. These processes can remove up to 90% of organic material from wastewater, thereby reducing BOD5 by the same percentage1. This treatment stage utilizes aerobic microorganisms to consume organic particulates and to convert ammonia into inert nitrates in a process known as nitrification. Nitrification levels in conventional secondary treatment are typically less than nitrification levels in alternative systems that utilize additional biologically-based treatments.1
Tertiary Treatment
Tertiary treatment often involves reducing nutrient levels, such as nitrogen and phosphorous. Nitrifying and denitrifying (the process of converting nitrates into nitrogen gas) bacteria are employed, and chemicals are added to catalyze the coagulation and sedimentation of phosphates1.
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Nitrification process tank in conventional treatment system.
Typically, tertiary treatment includes a disinfection process. In conventional wastewater systems, the water is disinfected with one or a combination of the following as part of tertiary treatment: chlorine, ozone, and ultraviolet radiation. This level of treatment is designed to kill any remaining pathogens present in the water1,2. In conventional systems, tertiary treatment is a highly technical and expensive process. However, similar results can be achieved in a less expensive and simpler fashion in alternative treatment systems that employ a variety of biological processes. References 1. [EPA] Environmental Protection Agency. 2004. Primer for municipal wastewater treatment
systems. Office of Water (EPA): Washington (DC).
Bank Group: Washington (DC).
2. The World Bank. 2014. Introduction to wastewater treatment processes. The World
On-Site, Biologically-Based Secondary Treatment Options The following treatment options are employed after effluent has passed through primary treatment. The settling of solids and anaerobic digestion in a septic tank constitute primary treatment.
Suspended Growth Aerobic Treatment 4, 5
Suspended growth aerobic treatment utilizes an aerated tank to encourage to growth of aerobic microorganisms. As a result, BOD5 is reduced significantly, and nitrogen levels are reduced due to nitrification. The effluent then passes through a clarifier to remove any remaining solids before being discharged. Advantages • Suspended growth aerobic treatment is a simple, cost-effective option. • Nitrification levels are relatively high, and BOD5 can be reduced to meet discharge requirements. • The system has relatively low space requirements. Disadvantages • Effluent may not reach tertiary levels of treatment in terms of pathogens, heavy metals, or phosphorous. • Tank aeration and pumping require electricity. • This treatment option does not contain any aesthetically pleasing elements. • The microorganisms involved do not form the foundation for a more complex ecosystem.
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Evapotranspiration System2
Evapotranspiration treatment systems employ the ability of vegetation to release water into the atmosphere in order to remove effluent from the site. Having passed through primary treatment, the wastewater is distributed into sealed, vegetated beds filled with a porous substrate, such as sand. The influent is absorbed by root systems, and capillary action brings some water to the surface where it evaporates directly. The remaining water, absorbed by the vegetation, is evapotranspired into the atmosphere. Advantages • Evapotranspiration beds are highly effective in areas where soil drainage is poor. • This system reduces the risk of the contamination of groundwater as compared to conventional on-site treatment systems. • Evapotranspiration systems are most effective in arid climates, such as the southwestern United States. • Substantial amounts of vegetation, including trees, are supported by such systems. • The vegetation creates an aesthetically-pleasing habitat for wildlife on site. Disadvantages • Evapotranspiration beds require large, flat areas; space requirements are high. • Effectiveness of the system can be governed by climatic conditions; weather events, such as precipitation, can overload the system. • Dormant vegetation in winter does not evapotranspire. • The system has limited storage capacity. • Accumulation of salts and other inorganic wastewater constituents in the beds will eventually limit vegetation growth.
Constructed Wetlands1, 4
Constructed wetlands are artificial wetlands for the purpose of treating effluent. Primary treated effluent is distributed into a sealed area filled with a range of substrate types, including gravel, sand, and loam. The system is planted with obligate wetland vegetation, which evapotranspire some of the water, while the root systems and porous substrates harbor both anaerobic and aerobic microorganisms. Nitrification, phosphorous uptake, and a reduction of BOD5 occur at high levels in a constructed wetland system. Advantages • Final effluent often reaches tertiary levels of treatment. • The system is composed of a highly productive ecosystem that provides habitat for a large range of organisms. • Wetland vegetation and associated organisms provide an aesthetically pleasing element to the site. • This type of system is relatively inexpensive to construct and operate.
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Disadvantages • While amounts may fluctuate, constructed wetlands require a continuous supply of water. • This system has relatively large space requirements. • The effectiveness of the system can be influenced by climate and weather events.
Eco-Machine3
An eco-machine combines processes from a variety of treatment systems. Following primary treatment, effluent passes through aerobic tanks, such as those in a suspended growth aerobic system. Next, the water moves into open, vegetated aerobic tanks. Some of the tanks may contain a variety of invertebrates and some vertebrates, including fish. The water passes through a clarifier and is then polished by small constructed wetland, discharged in evapotranspiration beds, or is discharged directly onto the landscape.
Pennsylvania State University eco-machine.
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Advantages • Effluent reaches tertiary levels of treatment; nitrification and denitrification levels are high. • The open aerobic tanks are complex, productive ecosystems that can act as educational displays. • The variety of vegetation in the open aerobic tanks and associated organisms provide an aesthetically pleasing element to the site. • This system is the most space-efficient for the resulting levels of treatment. Disadvantages • Much of the system requires a greenhouse for reliable operation. • Without polishing, phosphorous removal is often less than other treatment options. • Aerated tanks and pumps require electricity. • Eco-machines have slightly higher capital costs compared to other on-site treatment options.
Conclusion
Without space restrictions, the ideal system for Milagro Arts Center would be an eco-machine where the effluent is polished by a constructed wetland and is then used for landscaping or other situations where evapotranspiration will occur. The resulting system cleans effluent to tertiary levels and provides a variety of habitats by supporting complex ecosystems; meanwhile the effluent is used entirely on-site. This combination also creates an aesthetic, educational element to the design of the property. However, the space restrictions of the property have acted as one of the primary design impulses, or influencing factors. Therefore, to achieve maximum treatment, while contributing to local ecological health and providing an educational aspect to the building, the design outlined in this report is a modified eco-machine. References 1. [EPA] Environmental Protection Agency. 1992. Subsurface flow constructed wetlands for 2. 3. 4. 5.
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wastewater treatment: A technology assessment. Office of Water (EPA): Washington (DC). [EPA] Environmental Protection Agency. 2000. Decentralized systems technology fact sheet: Evapotranspiration. Municipal Technology Branch of the U.S EPA: Washington (DC). [EPA] Environmental Protection Agency. 2002. Wastewater factsheet: Living Machines. Municipal Technology Branch of the U.S EPA: Washington (DC). Massoud MA, A Tarhini, JA Nasr. 2008. Decentralized approaches to wastewater treatment and management: Applicability in developing countries. Journal of Environmental Management. [WERF] Water Environment Research Foundation. 2011. Factsheet T2: Suspended growth aerobic treatment. Water Environment Research Foundation: Alexandria (VA).
Pollutants Organic Particulates
Biodegradable organic material and other pollutants, such as ammonia, provide aerobic microorganisms with a food source. The microorganisms consume the organic particulates and dissolved oxygen; these particulates are known as oxygen-demanding substances, and their relative levels determine the measure of biological oxygen demand (BOD) of the wastewater. BOD is often measured based on the demand over a five day period, therefore this measure is abbreviated, BOD5. When wastewater with high BOD5 is discharged, microorganisms flourish, and the rapid consumption of oxygen creates hypoxic conditions that are fatal to aerobic organisms1,2.
Pathogens
Waterborne, disease-causing pathogenic bacteria can infect drinking water sources, if discharged wastewater is untreated. Pathogens are present in human waste and other fecal matter, making domestic effluent and agricultural runoff sources of infected water 1,2.
Biological Nutrients
The elemental building-blocks of life, i.e., carbon, nitrogen, and phosphorous, are major constituents of wastewater. Expensive and highly technical processes involved in tertiary treatment remove such nutrients, however the costs of these processes are often prohibitive. When nutrient-rich wastewater is discharged into a body of water, ecosystems become overloaded with nutrients and enter a condition known as eutrophication. Eutrophication leads to algae blooms, which block sunlight from penetrating into the water column and cause hypoxic conditions when the algae decompose1,2.
Inorganic and Synthetic Chemicals (Technical Nutrients)
Compounds, such as pharmaceuticals, synthetic pesticides, various industrial chemicals, and heavy metals, can be highly toxic to aquatic life and other organisms at low concentrations. Conventional wastewater treatment systems do not effectively remove these materials. Some aquatic plants and fungi can breakdown some synthetic organic compounds or uptake some heavy metals1,2. References 1. [EPA] Environmental Protection Agency. 2004. Primer for municipal wastewater treatment systems. Office of Water (EPA): Washington (DC). 2. The World Bank. 2014. Introduction to wastewater treatment processes. The World Bank Group: Washington (DC).
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Design the beginning? Why allow technical and he wastewater treatment system biological nutrients to mix only to expend designed for Milagro Arts Center energy downstream to separate them? is a slightly modified eco-machine. These ideas focus on ecological health Our design is modeled significantly affurther upstream – eliminating hazards to ter the eco-machine currently operating the photographers and preventing toxic adjacent to the Center for Sustainability on materials from accumulating in ecosystems. the Pennsylvania State University campus6. Combining biological and technical maHowever, our design lacks one element terials inherently creates issues of higher of the Penn State eco-machine, the conmagnitude further downstream as it renstructed wetland. The following system is ders both sets of materials useless. designed to treat effluent from Milagro Arts Ultimately, to avoid the creation of a Center to post-secondary levels. monstrous hybrid, we decided that the effluent stream from the bathrooms should be separated from the wastewater proMajor Impulses duced by the remainder of the building. By focusing exclusively on the bathroom At the commencement of the design effluent, our treatment system would deal process, we identified various impulses, or with only biological nutrients. We believe influential factors, that would dictate and that to undertake the issue of toxicity in shape the final product. The major impulses analog photography development requires we identified are the following: wastewaan entirely separate design that focuses on ter constituents, available space, and daily the development process itself, rather than effluent loads. To a lesser extent, overall systhe effluent produced. tem cost and solar exposure impacted the design outcome.
T
Available Space
Wastewater Constituents
Of the various art-making processes and techniques planned for the Milagro Arts Center, analog photography development is an outstandingly toxic and water-intensive process4. Specifically, a major concern was the discharge of heavy metals, such as selenium and chromium, into the waste stream. This issue prompted us to ask, rather than design a system to mitigate the toxicity of the effluent from photography development, why not focus on utilizing less toxic materials in the process from
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Milagro Arts Center is located within an urban landscape. Space between buildings is negligible and parking space is paramount; overall, open space is severely limited. However, there is a vacant area purposefully included in the architectural plan that is between the rear of the main building and the kiln shed. This space, while our only viable option, is also designated for social gathering. This designation required our design to allow for the flow and gathering of people in the space while also enhancing it.
Daily Effluent Loads
Inherent in dealing with the impulse of available space was determining the overall volume of the system. This meant estimating the daily effluent load from the bathrooms. These estimates utilized established figures, such as flow rates of various fixtures and the number of such fixtures. However, the estimates also required several assumptions, such as the number of people using each bathroom per day and the average amount of time the sinks will be used. Overall, our estimates show that a treatment system capable of treating 1,000 gallons per day will be sufficient for the building, including normal use and large events.
Toxins Potentially Involved in Analog Photography Development Processes Acids
Bases
Acetic acid (D; SB) Boric acid (FB) Hydrochloric acid (I, R)
Developing powders (various alkaline substances) (D) Sodium hydroxide (DB) Sodium carbonate (DB)
Heavy Metals
Potassium chromium sulfate (FB) Potassium dichromate (I, R) Potassium chlorochromate (I, R) Selenium (T)
Organic Compounds
Monomethyl-p-aminophenol sulfate (DB) Phenidone (DB) Hydroquinone (DB) Para-phenylenediamine (DB)
Other
Potassium bromide (DB) Sodium sulfite (DB) Sodium or potassium cyanide (I, R) Potassium ferricyanide (I, R) D – developers DB – developing bath SB – stop bath FB – fixing bath I, R – intensifiers and reducers T - toners References McCann, Michael. 1994. Photographic processing hazards. Center for Safety in the Arts: New York (NY).
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Daily Effluent Load Estimates Number of People Daily Bathroom Effluent 50 330 gal 75 495 gal 100 660 gal 125 825 gal 150 990 gal 175 1,156 gal These estimates are based on several assumptions, namely that each person will use the toilets twice and the sinks three times. Additionally, it is assumed that the sinks will flow for 30 seconds per use. The established figures used in these estimates are that the sinks flow at 2 gal/min, the toilets use 1.8 gal/flush, and that there are four sinks and four toilets.
Eco-Machine Mechanics The eco-machine at Milagro Arts Center will be composed of four treatment components. The effluent from the building will flow through an (1) anaerobic reactor, (2) closed aerobic reactors, (3) open aerobic reactors, and (4) a clarifier.
Step 1: Anaerobic Reactor The initial step of the treatment process is the 3,000 gallon anaerobic reactor3,6. This component is composed of a double chambered septic tank buried below grade. The primary purpose of the anaerobic reactor is to reduce suspended solids through the process of sedimentation, which also reduces the measure of BOD53. Anaerobic
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bacteria begin to digest the accumulated primary sludge; however, periodic septic pumping is required to prevent a significant buildup of sludge. Gases are released via a carbon filter for odor control. This step encompasses primary treatment3. A float-operated submersible pump will operate when levels in the tank reach 2,500 gallons. The pump will remove 250 gallons each time it operates.
Step 2: Closed Aerobic Reactors The semi-clarified effluent from the anaerobic reactors will flow into two, 1,000 gallon, closed aerobic tanks. The tanks are passively connected with piping to allow overflow from the first to enter the second6. The tanks will be aerated using a conventional septic aerator pump; the aerator tube
Overview of the eco-machine.
in the second tank will have a fine bubble diffuser attachment. This oxygenated wastewater will allow for the proliferation of aerobic microorganisms that work to nitrify and denitrify the water and significantly reduce BOD5. The first closed aerobic tank will be aerated to a lesser degree than the second; it will have dissolved oxygen levels less than 0.4 mg/L 3. The lower dissolved oxygen levels in the first tank encourage different types of floc-forming and denitrifying bacteria and make the conditions in this tank slighly more anoxic than the second tank3,6. All remaining odorous gases are released in this step via carbon filters. The second float-operated pump in the system will be installed in the second closed aerobic tank. When water levels
reach 850 gallons in the second tank, the pump removes 250 gallons.
Step 3: Open Aerobic Cells Overall, the capacity of this component will be approximately 1,800 gallons6. The number of open aerobic tanks may vary from three to six depending on the type of material and size of each tank. The variety of tank sizes and materials correspond with a variety of costs and aesthetic qualities. For the purposes of this description, we will assume three rectangular, 630 gallon transparent tanks. Each of the tanks will have an open top and will be aerated with fine bubble diffusers3. The surface of the water will be covered in shade-tolerant aquatic vegetation supported by racks, or the
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plants will be free-floating. The combined surface area of the root systems will provide colonization surfaces for a variety of aerobic microorganisms that will complete the nitrification process and reduce BOD5足 to post-secondary levels3. The vegetation will uptake nutrients, such as phosphorous, as well. If the vegetation dies due to an event, such as freezing, coarse netting submerged in the tanks can act as a substitute for the root mass by providing surfaces for microorganisms to colonize. The tanks are inoculated with microorganisms with fine-particulate organic sediments gathered from local lacustrine or riverine systems. A float-operated pump will move water from the last open aerobic tank into the next component. This component can support a complex ecosystem. In addition to the vegetation and nitrifying bacteria, invertebrates, such as Mayfly (order Ephemeroptera), Dragonfly, and Damselfly (order Odonata) larvae and small, freshwater snails (Physa sp.), can inhabit the tanks2. Additionally, various small fish species can inhabit the later tanks. Fish species may include a freshwater fish native to Arizona, the Speckled Dace (Rhinichthys osculus)1. Or, the tanks may include fish not native to the state, such as the prolific Mosquito Fish (Gambusia affinis), the Southern Redbelly Dace (Chrosomus erythrogaster), or the small, hardy Sticklebacks (family Gasterosteidae)5. The vegetation used in the open aerobic component must be shade-tolerant due to the north-south orientation of the courtyard. Vegetation for the open aerobic tanks may include the following7:
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American Marshpennywort (Hydrocotyle americana) Arrow Arum (Peltandra virginica) Various Bulrush (Schoenoplectus spp.) Deertounge (Dichanthelium clandestinum) Floating Primrose-Willow (Ludwigia peploides) Golden Club (Orontium aquaticum) Mexican Waterlily (Nymphaea mexicana) Various Rush (Juncus spp.) Various Sedge (Carex spp.) Various Spike Rush (Eleocharis spp.) Watercress (Nasturtium officinale)
Step 4: Clarifier The purpose of the clarifier is straightforward. This 300 gallon, cone-bottom tank acts as a settling tank for remaining solids; it clarifies the water from the many dead microorganisms that have accumulated during the previous steps. Duckweed will cover the surface of the water to prevent algal growth. Solids are removed and recycled back into the closed aerobic reactors. The fourth float-operated pump in the system removes 250 gallons from the clarifier whenever water levels reach the top of the tank. The water moves from the clarifier into the city sewage. Until it is determined that the effluent from the system reaches discharge requirements, it is safest to allow the water to be treated conventionally.
Rendering of custom transparent tanks. View looking south.
The system may also include an optional fifth component. After the clarifier, a gravel-filled, shallow tank planted with vegetation, such as Cattails (Typha spp.) and Equisetum, will polish the water. The purpose of this component is to further reduce BOD5 and phosphorus levels. This component should be placed along the southern wall of the kiln shed.
Project Phasing Phase 1: Construction of the four part system with effluent discharging into city sewage. This phase includes any tank construction and placement, plumbing, and other structural requirements.
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The adjacent images are three potential eco-machine layouts. The options are based on the type of tanks used for the open aerobic cells. Each of the plans restricts the space between the open aerobic tanks and the main building to a different degree. The custom concrete tanks allow for a 6’ 5” passage, the transparent tanks allows 6’4” of space, and the polyethylene tanks allow for 5’11” of space. While the concrete tanks allow for the most space between the open aerobic component and the building, four tanks are required due to the thickness of the material. This restricts space overall. Additionally, while the polyethylene tanks restrict the passageway between the system and the building the furthest, these tanks have the lowest overall cost. The anaerobic tank and closed aerobic tanks are placed outside of the courtyard, in the parking lot. The anaerobic tank is set below grade.
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Phase 2: Filling the closed aerobic tanks with water in order to begin propagation of
vegetation. These tanks will be inoculated with microorganisms present in local lacustrine and riverine organic sediments.
Phase 3: Determining the actual effluent loads from the bathrooms. These figures will be used to adjust flow rates through the system. Another aspect of phase three is testing the final effluent for BOD5, TSS, nitrogen, phosphorous, and other wastewater constituents. Phase 4a: If final effluent reaches tertiary levels of treatment, it will be stored for
non-potable use within the building and landscaping.
Phase 4b: If effluent does not reach tertiary levels, water from the last open aerobic
tank can be recirculated to the first open aerobic tank. Recycling the water doubles the retention time in this component, thereby treating the water further. To supplement the recirculation within the open aerobic component, additional vegetated aerobic tanks or constructed wetland can be installed after the clarifier. This additional step will polish the water by further reducing BOD5, phosphorous, and other harmful wastewater constituents. When this phase is complete, return to phase 4a.
Cost Analysis Four 470 gallon Three 630 gallon Six 360 gallon Concrete Tanks Transparent Tanks Polyethylene Tanks All Tanks $7,120 $7,160 $6,980 Aerator Pumps x 4 $570 $570 $570 Water Pumps x 3 $750 $750 $750 Vent Carbon Filters x 3 $150 $150 $150 Plumbing $110 $110 $110 Total + 7.35% tax $9,339 $9,189 $9,382 Material
The cost analysis is separated into three options based on the types of tanks used in the open aerobic component. The costs for the custom-built concrete and transparent tanks are estimates based on concrete and Plexiglas costs, respectively. The base of the transparent tanks will consist of a concrete slab. Note that the above estimates do not include labor and they are based on all new materials.
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References 1. [AGFD] Arizona Game and Fish Department. 2002. Rhinichthys osculus. Unpublished abstract compiled and edited by the Heritage Data Management System, Arizona Game and Fish Department: Phoenix (AZ). 2. Astheimer, Bryan. 2005. Species observed in the AEES model system. Unpublished document sent as a personal communication from Tania M. Slawecki, Ph.D.. Materials Research Lab: University Park (PA). 3. [EPA] Environmental Protection Agency. 2002. Wastewater factsheet: Living Machines. Municipal Technology Branch of the U.S EPA: Washington (DC). 4. McCann, Michael. 1994. Photographic processing hazards. Center for Safety in the Arts: New York (NY). 5. McLarney, Bill. 1984. Native fish for home aquariums. Mother Earth News, Ogden Publications: Topeka (KS). 6. Slawecki, Tania M. 2005. Elements of the Living Machine and their requirements at 700 gal/ day. Unpublished document sent as a personal communication from Tania M. Slawecki, Ph.D.. Materials Research Lab: University Park (PA). 7. [USDA] U.S. Department of Agriculture.2014. Plant database: Plant profiles. USDA Natural Resources Conservation Service: Washington (DC).
Legal Considerations and Water Quality Several permits may be required for the treatment system outlined in this report due to the combination of anaerobic, aerobic, and nitrate-reactive processes. The permit requirements include surface discharge requirements, however, during the first phase of implementation the effluent is discharged in to city sewage. In later phases, effluent will be stored for reuse on the property. The discharge requirements outlined in the permits may be less stringent than what is preferred (see table below). The following are found in Title 18: Environmental Quality, Chapter 9: Department of Environmental Quality Water Pollution Control:
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R18-9-A309. General Provisions for On-site Wastewater Treatment Facilities R18-9-E315. 4.15 General Permit: Aerobic System Less Than 3000 Gallons Per Day Design Flow R18-9-E316. 4.16 General Permit: Nitrate-Reactive Media Filter, Less Than 3000 Gallons Per Day Design Flow R18-9-E321. 4.21 General Permit: Surface Disposal, Less Than 3000 Gallons Per Day Design Flow Additionally, septic tanks are permitted for installation in the City of Prescott via Yavapai County. Yavapai County has a specific septic permit for alternative systems.
The table below is composed of World Health Organization and Environmental Protection Agency drinking water guidelines that are relevant to the quality of eco-machine effluent1,2,3. Parameter Total dissolved solids pH Turbidity Fecal coliform of E. coli Giardia lamblia Nitrate Nitrite Sulfate Sodium Lead Iron Fluoride Chloride Copper Cadmium Aluminum Zinc
Guideline Value 500 mg/L 6.5-8.5 5 NTU Not detectable in a 100 mL sample None 10 mg/L 1 mg/L 250 mg/L 200 mg/L 0.01 mg/L 0.3 mg/L 1.5 mg/L 250 mg/L 2 mg/L 0.003 mg/L 0.2 mg/L 3 mg/L References
1. [EPA] Environmental Protection Agency. 2009. National primary drinking water regulations. Office of Water (EPA): Washington (DC). 2. Mosley, Luke. 2005. Water quality of rainwater harvesting systems. SOPAC: Pacific Island Applied Geoscience Commission: Suva (FJ). 3. [WHO] World Health Organization. 1996. Guidelines for drinking water quality, 2nd Edition, Vol. 2. World Health Organization: Geneva (CH).
Case Studies There is growing interest and support for on-site, biologically-based wastewater treatment systems across the globe. Many public and private organizations, such as the Findhorn Ecovillage in Moray, Scotland, are employing eco-machines to treat the entirety of their effluent. Other institutions are using eco-machines to treat a percentage of their effluent as part of a larger green initiative, as a trial-run, or for other experimental purposes. Some colleges and universities have embraced experimental wastewater treatment
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systems, such as Oberlin College in Ohio and Pennsylvania State University. Additionally, several companies that construct eco-machines have emerged in recent years, including Living Machine Systems L3C, Ecological Engineering Group, and John Todd Ecological Design.
Julian Woods Community Center5 The Julian Woods Community is a group of 20 individuals in Julian, Pennsylvania. Their on-site wastewater treatment system processes 1,200 gallons per day (gpd) of wastewater. The community decided to build an eco-machine rather than a conventional treatment system despite 30% higher capital expenses. The current system was constructed, for the most part, by the community and it is operated exclusively by the individuals living on site. The Julian Woods Community eco-machine is unique because influent flows through a wetland system before and after the open vegetated tanks. After flowing through the second wetland, half of the water is used to flush toilets, and the other half travels to evaporation beds where flowers are grown to be sold at local markets. Maintenance is limited and entails only two monitoring visits per week to record temperature, water flow, water level, and for general plant maintenance. The septic tanks need to be pumped every three to five years.
Findhorn1 One of the better-known eco-machines in the world is in the Findhorn Ecovillage in Moray, Scotland. Built in 1995, it is designed to treat wastewater produced by the 500
Findhorn Ecovillage eco-machine.
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residents of the complex. Additionally, it serves as a research and educational resource. With a relatively low start-up cost, the eco-machine meets effluent discharge standards; treats 17,000 gpd to tertiary levels. The eco-machine acts as a pilot project in Europe, and data collected from the project is used to inform future designs and implementation, and it allows the current design to be adapted for optimal performance. According to Findhorn’s website, “the resulting research [from the eco-machine] shows that the wise use of modern materials, biomimicry, and design innovation, provide an effective solution to the problems of urban water pollution and aquatic habitat degradation.”
Oberlin College3 Oberlin College’s Adam Joseph Lewis Center for Environmental Studies in Ohio is home to an eco-machine capable of treating 2,500 gallons per day. It is an invaluable educational tool for both environmental studies and sustainability-focused design on campus. The primary function of the machine is to treat wastewater, which is then cycled back through the building for a variety of non-potable uses. It has a 1,500 gallon anaerobic reactor, and two 1,500 gallon closed aerobic reactors that are buried below grade. Following these steps, the water flows into a greenhouse that contains three open aerobic tanks, a 500 gallon clarifier tank, and a 4,500 gallon constructed wetland for polishing. After polishing, it goes through ultraviolet treatment to kill any remaining pathogens and is stored for use in the building in order to flush toilets. The entire system is monitored thoroughly to ensure high levels of efficiency and effectiveness. Despite its large capacity, it has been underutilized and there have been many recent campaigns to acquire more ‘food’ for the machine from the students. Oberlin’s online monitoring shows an increase of recycled water from the machine being used. In April 2014, the Adam Joseph Lewis Center has used over 7,000 gallons of recycled water.
Oberlin College eco-machine.
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Pennsylvania State University4 At Pennsylvania State University, the senior class of 2000 gifted the school an eco-machine. It is capable of handling 1,000 gallons of wastewater per day. The eco-machine was created using plants that were donated from an eco-machine elsewhere in the country, and mud was harvested from the bottom of local ponds and streams. All of the components of the eco-machine are contained within a greenhouse. The eco-machine consists of a septic tank, two closed aerobic tanks, three open aerobic tanks, a clarifier, and a unique fluidized bed that runs across the floor of the greenhouse. The water is then utilized for non-potable uses, including ponds and landscape irrigation.
South Burlington5 The South Burlington eco-machine in Vermont is an example of a large municipal system. It is designed to treat 80,000 gallons per day produced by the 1,200 residents. The influent, having passed through primary treatment, flows into a series of five open aerobic reactors then enters a clarifier. After the clarifier, it flows into ecological fluidized beds that perform final polishing. The system has been successful, even at near- maximum capacity. The South Burlington eco-machine has become a standard for its type of design for municipal treatment, and it is a valuable asset for experimental research and education.
South Burlington eco-machine.
Design Standards and Preliminary Results for South Burlington Eco-Machine Influent Target Effluent Effluent COD mg/L 454 <50 31.3 BOD mg/L 219 <10 4.8 TSS mg/L 174 <10 4.8 Total Nitrogen mg/L 23 <10 2.2 Total Kjeldahl Nitrogen mg/L 23 5 1.3 Ammonia mg/L 14 1 0.25 Total Phosphorous mg/L 4.8 3 2.2 Fecal Coliform colonies/100L 9,380,833 <2,000 1,177
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References 1. Findhorn Ecovillage. 2014. Ecological wastewater treatment. Findhorn Ecovillage: Moray (SCT). 2. John Todd Ecological Design. 2014. South Burlington Municipal Eco-Machine City of South Burlington, Vermont. Ocean Arks International: Falmouth (MA). 3. Oberlin College. 2014. Adam Joseph Lewis Center building dashboard. Oberlin College: Oberlin (OH). 4. Slawecki, Tania M. 2005. Elements of the Living Machine and their requirements at 700 gal/ day. Unpublished document sent as a personal communication from Tania M. Slawecki, Ph.D.. Materials Research Lab: University Park (PA). 5. Steinfeld, C and David Del Porto. 2007. Reusing the resource: Adventures in ecological wastewater recycling. Ecowaters Books: Concord (MA).
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Concluding Thoughts Limitations
W
hile there are many advantages to the design outlined in this report, there are several limitations that must be recognized. The mitigation of some of these issues may be simple and effective, while other issues are inherent to the design and cannot be alleviated substantially. The limitations include the following: • Phosphorous levels may not reach levels required for tertiary treatment. This issue can
be mitigated via the additional steps outlined in phase 4b.
• Orientation of courtyard limits sun exposure. The use of primarily shade-tolerant
vegetation alleviates this significantly. However, temperature regulation in the courtyard is reliant upon the thermal mass of the tanks as well as the massive walls of both buildings.
• The overall cost of the system is relatively high. By purchasing used materials, such as
tanks, or repurposing salvaged materials, the overall cost can potentially drop significantly.
• The treatment abilities of an eco-machine do not lend themselves to predictability.
This is a characteristic inherent in the type of design. The construction of similar systems is often a trial-and-error process.
• Actual effluent loads are unknown; the system may require adjustments soon after
construction.
• The system requires consistent maintenance, e.g. sludge removal and pruning vegeta-
tion.
• The aerobic cells may need to be covered in the winter, i.e. a greenhouse. A simple
removable frame covered in plastic sheeting can be placed over the tanks during the months when freezing temperatures are likely.
Moving Forward Beyond the scope of this design, there are several ways to improve the eco-effectiveness of the Milagro Arts Center. In this case, the physical design and technology of the building lend themselves to resource conservation, however, it is the users of the building that must uphold and manifest ecological consciousness in their collective behavior. Therefore, we believe that further improvements will potentially focus on the behavioral aspects of how the building is used. For instance, water use can be reduced significantly through changes in behavior, rather than improving the efficiency of any given technology. Additionally, a reduction in the toxicity of photography development and other pro-
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cesses would be a major step towards a sustainable and regenerative arts center. While this is a challenge, it could have significant impacts on local water quality, ecological health, and act as an example for other studios and art centers.
Towards a Regenerative Future When dealing with seemingly technical issues, such as wastewater treatment, conventional solutions are often highly complicated engineering projects. These systems perpetuate the linear lifespan of nutrients and other materials. Meanwhile, the purification and recycling of water and other resources are inherent in all natural systems. By employing complex biological and ecological processes, we can create simple, elegant solutions. Onsite treatment systems help alleviate our growing dependence on centralized wastewater treatment facilities, and help reestablish a connection to the nutrient cycles we are all a part of. Through the imitation of natural systems, we recognize that waste equals food and that all materials progress through the world in perpetual cycles.
View of the lower Verde River near the confluence with the Salt River.
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Appendix The following linked webpages have informed the design and may prove useful in the implementation process:
Eco-machines • http://water.epa.gov/scitech/wastetech/upload/2002_12_13_mtb_living_machine.pdf • http://www.uvm.edu/rsenr/nr385c/resources/documents/The%20design%20of%20living%20 technologies%20for%20waste%20treatment.pdf • http://environment.uwaterloo.ca/research/watgreen/projects/library/f04livingmachine.pdf • http://yosemite.epa.gov/water/owrccatalog.nsf/9da204a4b4406ef885256ae0007a79c7/ 5d2a6584de0e37df85256b06007254a3/$FILE/The%20Living%20Machine%20Wastewater%20 Treatment%20Technology.pdf
Wastewater Processes and Management • • • •
http://www.epa.gov/owm/septic/pubs/septic_management_handbook.pdf http://www.lut.ac.uk/well/resources/technical-briefs/64-wastewater-treatment-options.pdf http://www.epa.gov/npdes/pubs/primer.pdf http://water.worldbank.org/shw-resource-guide/infrastructure/menu-technical-options/wastewater-treatment
Materials
Tanks
• • • •
•
http://www.ntotank.com/360gaoptopta.html http://www.eplastics.com/Plexiglass_Acrylic_Sheet_Clear http://www.tank-depot.com/productdetails.aspx?part=A-VT1000-64 http://www.plastic-mart.com/product/5797/300-gallon-45-degree-cone-bottom-tank- cb0300-42 http://www.jensenprecast.com/Septic-Tanks/Residential-Septic-Tanks-p4060/
Water Pumps
• http://www.homedepot.com/p/Wayne-1-2-HP-Cast-Iron-Sewage-Pump-with-Tether-Float Switch-RPP50/203448480?N=5yc1vZbqpc#specifications • http://powerequipment.honda.com/pumps/models/wsp33
Aerator Pumps
•
http://www.septicsolutions.net/store/cycloneairpumps.html
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•
http://www.septicsolutions.net/store/hiblowlinear.htm
Vent Filters • •
http://www.odorhog.com/ http://www.homedepot.com/p/Sweet-Air-Vent-Stack-Filter-VS-TT/203414047
Permits • http://www.azsos.gov/public_services/title_18/18-09.htm • http://www.yavapai.us/devserv/environmental-services-division/septic-system-construction/
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