Spring semester 2017 at HSU, our team of four ENGR305 students were assigned the task of revamping the greywater system located at CCAT. While researching the past project we came to the conclusion that the current system had major problems that needed more than a simple fix. Researching many different forms of greywater systems, it became clear that this three person household didn't need an entire pond, it was oversized. Resulting in the system described to you below, set up with the same basic principles just flowing through a recycled bathtub. Another problem with the previous CCAT system was its inability to provide the campus with educational inspiration. The new installed system is very visible to the daily passerby and its small, above ground components are much clearer to understand. A very important aspect of appropriate technology. Our goal with this project is to provide a base of knowledge for the passerby about the importance of constructed wetlands. All the while providing CCAT with the means to properly dispose their greywater in an environmentally friendly fashion.
Background[edit | edit source]
The Campus Center for Appropriate Technology (more colloquially know as CCAT) since it's inception in 1978, has been representative of an accessible educational and demonstrative platform; both maintained by and intended for students, CCAT encourages decentralized, innovative and organic solutions to everyday problems. Propagation and emphasis of appropriate and sustainable technology has made it one of the top authorities on campus, within the context of environmental science and environmental resource engineering. Since 1978, it's members have grown from few to a robust and well developed community, of directors, employees and volunteers.
CCAT was originally located on the grounds where the Behavioral and Social Sciences (BSS) now stands, and was relocated in 2004 in order to accommodate. The previous location included a functioning greywater constructed wetland system, but was lost to the construction of the BSS. In 2007, plans were designed and implemented for a new marsh system, that was meant to serve as a demonstrational, self-sufficient irrigation system. This first design was implemented in 2008 (see CCAT greywater marsh (2008)), followed by a second attempt in 2009 (see CCAT greywater marsh (current)) which built on the existing system installed. However throughout its life and structural fluctuation, the design purpose of CCAT's greywater marsh has remained consistent and intended to be multi-purpose: integration of wetland technology, sustainable greywater management strategy and educational opportunity. Both projects (2008 and 2009) encountered problems that dealt with an array of complexities, but most notably are the difficulties that arose in designing efficient and adapted components of the system. These were as follows: primary treatment for kitchen wastewater (as marsh technology is considered secondary treatment), a structurally sound surge tank, efficient baffles that divert the water in a "maze-like" fashion and finally, arguably the most challenging component, efficient conveyance that provided access to the greywater effluent pipe that rests some feet beneath the ground. The key to an efficient constructed wetland is adaption of the system to complement the local environment meant to house it; thus the success of such a system at CCAT's current location proved to be quite an undertaking for previous projects as so many structural factors had to be accounted for. The system was always intended to be a constructed wetland meant to replicate aerobic processes via microorganisms that are sustained by the plants planted in the wetland. Both artificial and organic wetlands are used as a means of secondary water treatment, presenting a perfect design opportunity to treat greywater for the purpose of irrigation.
Problem statement[edit | edit source]
Initial[edit | edit source]
The objective of this project was to redesign and reconstruct the greywater marsh system at CCAT. Initially one of our primary goals was to update the surge tank of the old greywater marsh, which is located beneath the metal grate on the right side of the CCAT driveway (when you are facing the house.) The function of a surge tank is to temporarily store water, neutralizing pressure; it prevents against "surges" of excess water entering the system. This neutralization allows the system to treat its sized-for capacitance only. We also planned to install a more sophisticated system for straining oils and solids out of the greywater influent, that originate from kitchen sink discharge. Potential options for such a system included the implementation of a biolfilter such as a woodchip biomass filter. Other updates were to include replacement of pond liner, reconstruction of baffles in order to elongate the process of phytoremediation and the introduction of native marsh species into the system. Lastly, out team planned to revamp the testing tank, a primarily cosmetic feature of the system. The function of a testing tank is to preserve a sample of water that may be tested in order to see if the constructed wetland is functioning as it should; an untreated influent (greywater) sample is tested as well as a treated influent sample and the BOD level of each is compared in order to evaluate the effectiveness of the system.
Final[edit | edit source]
Because of structural limitations that mitigated the extent to which the old system could be reconstructed, we decided to do away with the old marsh altogether and design a completely new system. Primary challenges we faced included relative inaccessibility to the conveyance that channels greywater from the house; conveyance is approximately three feet underground, eliminating the option of a gravity-fed system. Because of this, we knew that incorporation of some form of pump mechanism would be necessary, in order to get the untreated greywater to ground level. Additionally, finding a usable treatment area that was not a waste of valuable space and that had some type of natural gradient (slope) to aid in water flow also constituted a challenge.
Our Criteria[edit | edit source]
In cohesion with our client CCAT, we came up with a set of criteria. Each criterion will have its own constraints and is ranked on a scale of 0 to 10 scale, 10 being of the greatest importance and 0 of the least.
| Criteria | Constraints | Weight (1-10) |
|---|---|---|
| Education Value | Signs must be at an 8th grade reading level. | 10 |
| Aesthetics | Must catch the attention of atleast 50% of the people that walk by. | 6 |
| Longevity | Must be a functional system for at least five years, with regular maintenance. | 8 |
| Accessibility | Must be user friendly and accessible to even the layperson. | 9 |
| Post Treatment Water Quality[1] | PM < 5 mg/L total suspended solids (TSS)
pH = 6.0-9.0 ≤ 10 mg/l BOD ≤ 2 NTU (Nephelometric Turbidity Unit) No detectable fecal coliform/100 ml 1 mg/l Cl2 residual (min.) |
10 |
| Capacity | Must be able to handle all of CCAT's greywater usage. | 7 |
| Reusable Material | Must have at least 80% reusable material. | 8 |
| Native Plants | Must include at least 75% native plants. | 5 |
Client Criteria[edit | edit source]
Education[edit | edit source]
As CCAT is designed to be a laboratory for sustainability, the greywater marsh system has undergone a series of changes and retrofits. A problem that has not been adequately addressed at any stage of upgrade is the lack of educational accessibility and opportunity. A home-tailored greywater system at CCAT has the potential to provide a visual and demonstrational platform for people to learn about greywater management in general, and perhaps even take this new information and adapt it to fit their own lifestyle and home. Our team currently considered the incorporation of truth windows in the system in order to promote greater educational accessibility. Truth windows are exactly what they sound like; they give the viewer or student a look into the function or structure of a specific component within a system. Truth windows are often employed in appropriate technology because they allow the participants and learners to see a system as a combination of interlocking components and also provide a more concise picture of the functionality of a particular component. Although the installation of a truth window never came to fruition, it would have served to compare the difference in water quality before and after treatment. For example, we would have placed one window so that the untreated greywater influent is visible as well as second window that displayed the clean and treated water flowing out of the system. This difference in quality would have demonstrated the potential constructed wetlands have to remove contaminants from greywater. It would have also proved that greywater can be managed at a household level safely and sustainably without threat to human or environmental health.[2]
Instead of a truth window, we designed as system with accessibility in mind. Our system most thoroughly serves the purpose of an educational platform rather than a full-scale treatment system, and is designed to allow for user interaction, specifically via the hand pump
Workability and Functionality[edit | edit source]
The two main problems with CCAT's current greywater system is the described inaccessibility to the educational component of the system and the overall functionality of the system itself. Currently, the marsh does receive greywater from the house that supplies the transplanted wetland species with water, but the surface treatment area is too large for the volume of water that is being discharged into the system. The water entering the old system (the untreated greywater influent) flowed with almost no velocity; this was likely due to an oversized surge tank. Liquid that flows from a smaller cross-sectional area to a larger one will slow in velocity. Overcompensation of a surge tank cross-sectional area would result in an almost total loss of velocity; this was what was observed in the old system. Lastly in relation to functionality, the system had no end use (an essential component within the context of appropriate technology) and the treated water was left to drain into the ground table.
Literature Review[edit | edit source]
This is a review of the available literature pertinent to Greywater Marshes.
Defining Greywater[edit | edit source]
The EPA defines greywater as "reusable wastewater from residential, commercial and industrial bathroom sinks, bath tub shower drains, and clothes washing equipment drains." Discharge from kitchen sinks is usually not considered greywater because of higher concentrations of organic material present in the form of cooking oils and solids. Greywater is categorically different from blackwater, in that it does not contain any fecal matter. Blackwater is defined as the the discharge from toilet outlets, and kitchen sinks in some literature. The high concentration of pollutants in blackwater create a site for bacterial growth that is potentially harmful to humans upon exposure.
Chemical Composition[edit | edit source]
The chemical composition of greywater is reflective of the households lifestyle. Any compounds used in soaps, detergents, hygiene products, etc. have the potential to be exposed to the installed greywater system and therefore have the potential to make up the composition of the subsequent greywater. Because of this the quality of greywater from any establishment is dependent on the inhabitants living standard, cultural norms, chemical usage and general lifestyle.[3]
The highest concentrated nutrients found in greywater are nitrogen and phosphorous. The majority of the nitrogen is deposited via kitchen sink discharge while the majority of phosphorous is originally contained in detergents and soaps, deposited via laundry units.
Potential Risks[edit | edit source]
When weighing the benefits and costs of implementing a household scale greywater system, many people are concerned about the potential risks that accompany the reuse of household water, to both human health as well as environmental. Risks to human health include the exposure pathogens from the digestive system and food handling pathogens, that are contained in untreated greywater. Such pathogens can cause disease through direct contact or the consumption of greywater plants and/or via contact with mosquitos. One environmental risk that accompanies the reuse of greywater is the potential for excess nutrients such as the phosphorus (contained in the untreated greywater) to enter local bodies of water, triggering eutrophication. However, upon extensive review of the available literature, it is clear that sustainable greywater reuse is possible without risking an overdose of phosphorus in the environment, but only if the system is correctly implemented. Additionally, a lot of people worry about the possible contamination of soils and aquifers from certain chemicals, oils and minerals that may change the soils characteristics. Such exposure to substances has the potential to cause salinization of soil, which reduces plant productivity. This salinization would be induced by high concentrations of salt in the greywater influent, originating from laundry detergent as well as other household cleaning agents. In order to reduce the potential for soil salinization, users should be mindful of household cleaning products they use, and what type of chemical compounds are contained in them.[4] Another environmental hazard is the potential for formation of xenobiotic organic compounds that are found in aquatic animals present in the resulting water. These compounds end up in the greywater from exposure to pharmaceutical drugs and antibiotics. To avoid this hazard, greywater system users must keep close regulation of the products being put down the drain. Last but not least are surfactants, or compounds that lower the surface tension between two liquids or between a liquid and a solid. Surfactants are used as detergents, emulsifiers, dispersants, foaming agents, etc… Although (as mentioned previously) you can use detergents that are not harmful for the environment, even the biodegradable compounds can reduce the ability of the soil to absorb water.[5]
However, if implemented properly, these risks can be minimized or completely reduced. A functioning constructed wetland mimics phytoremediation that occurs naturally in wetland settings. Rhizomes of marsh species are capable of removing the excess nutrients (phosphorous) and possible pathogens. Greywater that includes discharge from kitchen sinks usually necessitates pretreatment via a biofilter or some other filtration mechanism in order to remove any sediments, salts, or cooking oils that could be potentially decrease system efficiency. Additionally, pretreatment removes surfactants that are harmful to soil upon exposure. All of these mitigations are listed below in the <Types of Greywater Management Systems> section. Finally, all risks considered, it is important to remember: "To date, no epidemiological survey supports claims that greywater usage at a single household scale is associated with higher morbidity."[6]
Legalities[edit | edit source]
Generally in the United States, municipalities are responsible for collection and regulation of both greywater and blackwater. However, decentralized, household scale treatment systems are becoming more and more common throughout California and many other parts of the United States. Below is a [Photo] depicting the cans and cannots of current state legislations. In CA and AZ, the current greywater law is a tiered approach that allows you to classify your utilization according to the size of your system. The first tier allows homeowners to divert their laundry water for garden irrigation without a permit. The second tier does require a permit, and provides you with regulations for a more complex system.[7]
There are many different standards for greywater reuse around the world, and the variation between these policies is great. In order to aid people living in regions with little to no regulation infrastructure, Maimon et. al. has provided a way to facilitate your own grey water risk assessment (quantitative microbial risk assessment or QMRA) of public health through Hazard identification, Exposure assessment, Dose-response characterization and risk characterization.[8] It is also critical to outline the local "governance" of your location in order to make sure that your system is up to code.
Types of Greywater Management Systems[edit | edit source]
Within in the context of prolonged drought conditions and controversial water allocation projects in California, alternative on-site greywater reuse systems have gained much momentum locally.[9] On a larger scale, these systems have been popularized in low and middle income countries where management services are inadequate or non-existent. Within these nations, if drainage infrastructure exists untreated greywater is discharged into storm drains and diverted into established aquatic systems. This compromises the health of these ecosystems, altering characteristics such as turbidity, nutrients and microbial content, chemical composition, etc. and can lead to imbalances such as eutrophication.[10] Where infrastructure is not present, untreated greywater is simply diverted into streets or open ground, presenting multiple risks to public health such as water-born diseases.
Water scarcity, lack of adequate infrastructure and various other catalysts have lead to decentralized greywater reuse efforts both in rural and urban communities. These systems are usually self-implemented and designed for on-site reuse. Treated greywater can be recycled to serve a couple different domestic purposes but the system must be designed specifically to fit source/type of greywater and need. A number of approaches are used to treat water but the most common uses for the final product are irrigation (outdoor) and direct water reuse via sinks and flushing (indoor). Indoor usage requires more intensive water treatment techniques than that of outdoor. Here are descriptions of the general design plan for the most popular systems:
Laundry Drum[edit | edit source]
Greywater treatment systems span a wide range of complexity. A system can be as simple as diverting used water from your washer to a drum that holds excess;[11] this is referred to as a "surge tank" (See definition in mechanisms.)A hose attached to the drum can then further divert the water to your crops directly or be hooked to an irrigation system. Because of the nature of the chemical composition of washing machine greywater, treatment is not as necessarily intensive so diverted water can be used directly to water crops (see chemical composition of greywater in introduction).[12]
Benefits[edit | edit source]
The benefits of this system are threefold: first is the duality of the washing machine's built in pump as a mode of washing clothes and a pump source for the greywater system itself; this system is not reliant on gravity. The second benefit is that because of the nature of the greywater source (washing machine) the water does not have to be treated and can be used directly for gardening. Lastly, the plumbing for most washing machine units is exposed providing easy access for diversion if you are a home renter.
Considerations[edit | edit source]
The largest complication to this sort of greywater system is the dependence of irrigation on the frequency of laundry days.
Laundry-to-Land[edit | edit source]
Land to laundry (L2L) systems embed the same purpose of the laundry drum (the source/type of greywater and need are the same) and was first designed by Art Ludwig, a greywater activist. Similarly to laundry drums, L2Ls divert used water from washing machine units via a three-way valve connected to the unit. The three-way valve allows for easy diversion of greywater to outside or to the main sewer line, to be used if your garden is becoming overwatered or bleach was added to the laundry load. This feature of the L2L differentiates the system from the laundry drum model. Additionally, the L2L model recommends installation of an anti-siphoning vent on the garden-side of the valve to ensure water is not taken up from the machine while it is filled. (See siphon definition in mechanisms).[13]
The biggest disparity between the two systems is the L2Ls application of mulch basins as a natural surge tank (see surge tank definition in mechanisms) to release water for irrigation gradually. Mulch is an organic material more commonly referred to as bark, compost or a combination of these that aid in soil insulation and mitigate erosion. Water is diverted via the valve and then directed through a series of underground pipes to these basin, filtering water through and allowing for gradual release of moisture to root systems. The diversion of water to underneath the landscape is another fundamental component of L2Ls. This is preventative of over-saturation that can lead to overwatering and mosquitoes breeding. Piping is usually buried underneath the ground and fed into the mulch basins.
Construction of the mulch basins is simple. It can either consist of a singular large trench or series of trenches that are dug around the vegetation, typically about 12 inches deep and filled with "coarse" mulch (i.e. woodchips)..[14] The dimensions of the basins should be designed with consideration to the volumetric load they will hold, or the amount of water that will "surge" into the basins. Additional components can be added to aid in treatment processes such as a an outlet chamber. Outlet chambers can be constructed by burying a overturned 5-gallon pot with holes drilled into the sides.[15] The chamber allows for solids to flow into the basin for biodegradation without clogging over time. This consideration is meant to treat greywater sources that contain solids, or otherwise sources that are not originating from washing machine units (see branched drain in Types.)
Benefits[edit | edit source]
Mulch basins simulate natural water filtration by serving as an organic surge tank. The suggested three-way valve is a feature that is not included in the laundry drum model and gives the user more control over irrigation frequency. Like the laundry drum model, the intended greywater source is washing machine discharge which does not require intensive treatment but the model can be tailored to fit other sources.
Considerations[edit | edit source]
Regular maintenance of the mulch basins is required. Designer Ludwig suggests re-digging basins every year or two to counteract erosion.[16] Additionally, adequate design in regards to mulch basin dimensions are essential to ensure water is effectively filtered to plants.
Branched Drain[edit | edit source]
This model was also innovated by Art Ludwig, and incorporates the same mulch basin component as an organic surge tank. However, this system is gravity-fed rather than dependent on the internal washing machine pump also allowing for the greywater source not to be limited to this unit. The defining characteristic of branched drain is somewhat self-explanatory; a series of pipes descending in circumference "branch" out from the system's water source input, allocating an initially large flow of water to smaller outlets. It is recommended that like the L2L model the piping is hidden beneath the landscape, though Ludwig's design allows for above ground piping system if the user so desires. Subsurface systems are categorically more sanitary and up to code.
Ludwig suggests three methods for "splitting" the flow from the source of greywater. The first mechanism involves the installation of "double ell" attachments which split pipes outlets in two, allowing water to be diverted into different pipes. A branched network can be created with these attachments so that smaller amounts of water are delivered to the necessary places. The second mechanism suggests leaving the water sources separated initially; that is creating separate piping systems for each source input, i.e. kitchen sinks, washing machine, bathroom sink and shower. The third mechanism simply suggests manually moving outlets so that no area becomes too over watered. A combination of all three of these can be constructed in order to fit the specific needs of your system.[17]
Benefits[edit | edit source]
Branched drain systems are primarily suited for property that is situated on some type of grade. The larger the degradation the more easy the installation process. This can either be beneficial or an impediment, depending on the nature of the property. This system is open to design interpretation and specialization because the amount of irrigation outlets should be based on the volume of greywater discharged. It can therefore be tailored to fit the needs of any specific property. This also alleviates over-watering because large surges of water can be distributed via branched diversion, delivering smaller amounts to the desired areas.
Considerations[edit | edit source]
Because this system is gravity fed it must be constructed so that the water is diverted downhill. This system cannot accommodate to uphill irrigation, without the supplementation of a pump. At least a 2% grade (¼" per foot) must exist in order for proper water flow and the pipes must be sloped to exact tolerance. That is, pipes must be installed so that they create a continuous, downhill conduit or else the system may not function correctly.[18] Additionally, all the considerations pertaining to mulch basin maintenance (see considerations for Land-to-Laundry systems) apply to this system as well as these are an essential component to filtration.
Constructed Wetlands[edit | edit source]
A constructed wetland (CW) or artificial wetland is a system inspired by the natural biological processes that are occur in wetland ecosystems. CWs can be categorically broken down into three different basic designs: subsurface, surface and floating treatment wetlands.
Subsurface wetlands simply imply diversion of greywater below surface level, limiting exposure to air. Subsurface wetlands can be further broken down based on diversion pathway: horizontal subsurface CWs allow effluent to pass parallel to the surface, propelled by gravity while vertical subsurface CWs allow for the release of water vertically.[19]In vertical systems, the water is technically discharged on surface, first watering the strategically chosen wetland plants. It then penetrates the soil to be filtered through the roots and lastly through the chosen substrate (sand, gravel, etc.) Vertical systems require less area as compared to horizontal systems but effluent must be discharged in intervals to avoid flooding, necessitating the implementation of a surge tank. While horizontal systems require more area, they have a larger capacity for discharge. The wetland systems themselves are comprised of the same basic components: a top layer of soil containing wetland species (preferably native to the area) and a medium of filtration. This medium is typically sand or gravel and serves as a platform for microbial growth and aids in filtration and absorption of greywater.[20] The bottom is either line with a waterproof synthetic material (such as pond liner or tarp) or organic insulating material such as clay in order to mitigate groundwater contamination.
Surface CWs (also called free-surface CWs) are structurally similar to subsurface systems but differ in that they allow for pooling of effluent. Once the effluent is discharged it slowly flows through a basin, allowing suspended sediment to settle. The water then moves downward and is filtered through the rhizomal network established by the planted wetland species. These networks are supportive of microorganisms which feed on the nitrogen and phosphorous contained in the effluent.[21] Pathogens are broken via natural decay, predation and exposure to UV radiation.[22]This exposure is an important disparity when compared to subsurface mechanisms. However, this exposure also creates a breeding ground for less desirable organisms such as mosquitoes. Suitable vegetation for surface CWs include emergent, submerged and subsurface plants.
Free-floating systems differ in structure drastically when compared to surface and subsurface wetlands. The design mimics some components of hydroponic growth, as organisms are planted on a floating mat or substrate in a pond. The stems of the plants are exposed to air, while the roots intake nutrients directly from the water column. The function of the established rhizomal system itself is the same as in a subsurface or a surface CW, except the network may be more extensive in the absence of a soil medium. The network also forms a microbial biofilm, a thin layer of cells. In this system the roots execute both biological and physical processes of treatment. That is they physically filter and trap particulates while also converting nitrogen and phosphorous via biochemical processes in the biofilm.[23]
Benefits and Considerations[edit | edit source]
Constructed wetlands are by far the most complex of the described management systems, with the most room for customization. They are also wide ranging and a number of hybrid systems that incorporate aspects from different designs are used to accommodate specific criteria. The biggest benefit of these systems is their self-sufficiency if installed correctly while perhaps the biggest drawback is the rigorous and involved process of design specialization and implementation.
Summary[edit | edit source]
The systems described are not representative of the entirety of greywater management approaches but are a summarized list of the most popular, decentralized, "low-tech" systems. Of course more exotic systems have been created such as rotating biological contactors which treat water via UV exposure and sequencing batch reactors which utilize activated sludge technology.[24] However these systems are not applicable to the layperson and thus not available for self-installation. For this reason they have been excluded from the scope of this review.
Previous CCAT Greywater System[edit | edit source]
As far as we know the most recent update for this project is the 2009 edition. Per Connor Kennedy, the CCAT grounds keeper (2017), this system has been redesigned many times since then.
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This is how the old greywater marsh came to us.
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This is the old settling area for the greywater.
Design[edit | edit source]
The current system is a simple design to filter CCAT's grey water. It starts by coming out of the house and flows to a first settling tank that is located underground next to the bike rack. This settling tank takes out particulates by slowing the flow of the water, giving the particulates time to settle on the bottom. From here the water is transpoted underneath the drive way and to a second settling tank right before the greywater marsh. This settling tank acts as an oil trap. From the here the water is directly poured into the marsh where it moves through a baffled filter system. Since there is no direct place for the water to go after it has been fully treated, it ends up just being run off.
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This is the exit pipe from the second settling tank to the marsh
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This is the first settling tank with the inflow (white) and outflow (black) pipes.
Problems[edit | edit source]
The known problems with the system include level ground, and too much surface area per volume of greywater. To begin, the ground where the pipe is laid has too even of a slope. This inhibits the water's ability to reach the actual location of the marsh. Finally, the built marsh has too much area to be effective. This current system was not designed with the small amount of water use of CCAT in mind.
Settling tank[edit | edit source]
The settling tank is a very simple design, but effective. The settling tanks acts like a sedimentation tank.[25] A sedimentation tank works by slowing the flow of water, allowing the suspended particles to settle onto the bottom. This collection of waste is called primary sludge,[26] and must be removed manually. The way that this settling tank is designed incorporates an oil filter into it. It is a series of two buckets, the second bucket is smaller than the first so that it can be suspended inside the first bucket. The water comes from a pipe that is attached to the roof of the system and pours through the oil filter and rises back up to the top where it flows through another pipe that leads to the marsh. This allows for the flow of water to stop, giving the suspended solids the ability to sink to the bottom and effectively be filtered out of the water.
Oil filter[edit | edit source]
The primary objective of an oil filter is to remove any oils that may be in the water. The reason for this is so that the marsh system does not become clogged. The oil filter is a part of the sediment tank design. This is simply a wire mesh sheet attached to the first bucket described above. This essentially acts as a screen[27] that traps and captures the oil. The oil is further filtered through the sedimentation trap part of the settling tank and settles to the bottom becoming primary sludge.
Baffled system[edit | edit source]
The baffled filtering system includes a series of up – flow chambers.[28] The water initially enters the first section. Then, as the water level goes up it overflows into a second section where it penetrates through the soil, filling up the area, and overflows into the next. It repeats this process until the water is fully filtered. This system is not effective with weakly polluted water, but is hard to clog.[29]
references[edit | edit source]
- ↑ https://nepis.epa.gov/Adobe/PDF/P100FS7K.pdf
- ↑ Maimon, Adi, Alon Tal, Eran Friedler, and Amit Gross. 2010. Safe On-Site Reuse of Greywater for Irrigation - a Critical Review of Current Guidelines. Environmental Science & Technology. 44, no. 9: 3213.
- ↑ Turner, Ryan D.R, Ryan D.R Turner, Geoffrey D Will, Les A Dawes, Edward A Gardner, and David J Lyons. 2013. Phosphorus as a Limiting Factor on Sustainable Greywater Irrigation. The Science of the Total Environment. 456 457: 287.
- ↑ Allen, L. (2015). Water Wise Home, Storey Publishing, Massachusetts. 46-139.
- ↑ Turner, Ryan D.R, Ryan D.R Turner, Geoffrey D Will, Les A Dawes, Edward A Gardner, and David J Lyons. 2013. Phosphorus as a Limiting Factor on Sustainable Greywater Irrigation. The Science of the Total Environment. 456 457: 287.
- ↑ Maimon, Adi, Alon Tal, Eran Friedler, and Amit Gross. 2010. Safe On-Site Reuse of Greywater for Irrigation - a Critical Review of Current Guidelines. Environmental Science & Technology. 44, no. 9: 3213.
- ↑ California Plumbing Code. 2013. Alternate Water Sources for Non-Potable Applications. California Uniform Building Code. 16a.
- ↑ Maimon, Adi, Alon Tal, Eran Friedler, and Amit Gross. 2010. Safe On-Site Reuse of Greywater for Irrigation - a Critical Review of Current Guidelines. Environmental Science & Technology. 44, no. 9: 3213.
- ↑ Press, Ellen Knickmeyer The Associated. "California drought spurring 'grey water' recycling at home." California drought spurring 'grey water' recycling at home. June 05, 2015. Accessed January 28, 2017. http://www.dailynews.com/environment-and-nature/20150605/california-drought-spurring-grey-water-recycling-at-home. .
- ↑ Morel, Antoine, and Stefan Diener. "Greywater management in low and middle-income countries." Review of Different Treatment Systems for Households or Neighborhoods (2006). .
- ↑ About Greywater Reuse. Greywater Action for Sustainable Water Culture. http://greywateraction.org/contentabout-greywater-reuse/.
- ↑ ÜSTÜN, Gökhan, and Ayşenur TIRPANCI. "Gray Water Treatment and Reuse." (2015): 119-139..
- ↑ Sturgis, Michael. "Laundry to Landscape, a How-To." Permaculture Magazine. June 03, 2016. Accessed January 27, 2017. https://permaculturemag.org/2016/06/laundry-to-landscape-a-how-to/..
- ↑ Sturgis, Michael. "Laundry to Landscape, a How-To." Permaculture Magazine. June 03, 2016. Accessed January 27, 2017. https://permaculturemag.org/2016/06/laundry-to-landscape-a-how-to/..
- ↑ Ludwig, Art. Create an oasis with greywater: choosing, building, and using greywater systems, includes branched drains. Santa Barbara, CA: Oasis Design, 2006..
- ↑ "Greywater Mulch Basins." The Walden Effect. August 16, 2012. Accessed January 31, 2017. http://www.waldeneffect.org/blog/Greywater_mulch_basins/..
- ↑ Ludwig, Art. Create an oasis with greywater: choosing, building, and using greywater systems, includes branched drains. Santa Barbara, CA: Oasis Design, 2006..
- ↑ Ludwig, Art. Create an oasis with greywater: choosing, building, and using greywater systems, includes branched drains. Santa Barbara, CA: Oasis Design, 2006..
- ↑ "Constructed Wetlands for Wastewater Treatment." FH Wetland Systems Ltd. - Constructed Wetlands. Accessed January 31, 2017. http://www.wetlandsystems.ie/constructedwetland.html..
- ↑ "Constructed Wetlands for Wastewater Treatment." FH Wetland Systems Ltd. - Constructed Wetlands. Accessed January 31, 2017. http://www.wetlandsystems.ie/constructedwetland.html..
- ↑ Tilley, E., et al. "Compendium of Sanitation Systems and Technologies-. Swiss Federal Institute of Aquatic Science and Technology (Eawag), Duebendorf, Switzerland." (2008): 10..
- ↑ Hoffmann, Heike, C. Platzer, M. Winker, and E. Von Muench. "Technology review of constructed wetlands Subsurface flow constructed wetlands for greywater and domestic wastewater treatment." Deutsche Gesellschaft für, Internationale Zusammenarbeit (GIZ) GmbH, Sustainable sanitation-ecosan program, Postfach 5180 (2011): 65726..
- ↑ Headley, T. R., and C. C. Tanner. "Constructed wetlands with floating emergent macrophytes: an innovative stormwater treatment technology." Critical Reviews in Environmental Science and Technology 42, no. 21 (2012): 2261-2310..
- ↑ ÜSTÜN, Gökhan, and Ayşenur TIRPANCI. "Gray Water Treatment and Reuse." (2015): 119-139.s.
- ↑ United States. Environmental Protection Agency. Wastewater managment. Primer for municipal wastewater treatment systems. Washington, D.C., California: U.S. Environmental Protection Agency, Office of Water, Office of Wastewater Management, 2004.
- ↑ United States. Environmental Protection Agency. Wastewater managment. Primer for municipal wastewater treatment systems. Washington, D.C., California: U.S. Environmental Protection Agency, Office of Water, Office of Wastewater Management, 2004.
- ↑ United States. Environmental Protection Agency. Wastewater management. Primer for municipal wastewater treatment systems. Washington, D.C., California: U.S. Environmental Protection Agency, Office of Water, Office of Wastewater Management, 2004.
- ↑ Imhof, Barbara, and Joelle Muhlemann. "Greywater treatment on household level in developing countries." February 2005.
- ↑ Imhof, Barbara, and Joelle Muhlemann. "Greywater treatment on household level in developing countries." February 2005.