Greywater (also spelled graywater , gray water and water gray ) or sullage are all waste water produced in households or office buildings from rivers without fecal contamination, ie all streams except wastewater from toilets. The sources of greywater include, sink, shower, bathtub, washing machine, or dishwasher. Since greywater contains fewer pathogens than domestic wastewater, it is generally safer to handle and easier to treat and reuse in place for flushing toilets, landscaping or crop irrigation, and other non-drinking uses.
The application of greywater reuse in urban water systems provides substantial benefits to the water supply subsystem by reducing the demand for fresh water and wastewater subsystems by reducing the amount of wastewater required to be delivered and processed. Processed treywater has many uses, such as toilet flush or irrigation.
Video Greywater
Overview
Definition
Greywater is all waste water generated from the source of a house or office building without contamination of dirt. Therefore, by definition, greywater does not include the disposal of highly contaminated toilet or effluent wastewater, called waste or blackwater and contains human waste.
Quality
Greywater usually contains some traces of excreta and is therefore not free of pathogens. Excreta comes from washing one's anal area in the bath and shower, or from laundry (washing underwear and diapers). The quality of greywater can deteriorate rapidly during storage because it is often warm, containing some nutrients and organic materials (eg dead skin cells) as well as pathogens. Greywater stored also causes odor for the same reason.
Amount
In households with conventional flush toilets, greywater accounts for about 65% of the total wastewater produced by that household. This may be a good source of water for reuse, as there is a close relationship between greywater production and the potential demand for toilet flushing water.
Practical aspects
Misconnections of pipes can cause greywater tanks to contain a percentage of black water.
Small traces of dirt that enter the greywater stream through the effluent from the shower, sink, or washing machine do not pose a practical hazard under normal conditions, as long as greywater is used properly (eg, seeping from wells or properly used in irrigated agriculture).
Maps Greywater
Treatment process
Separate treatment of greywater is under the concept of source separation which is one of the most commonly applied principles in ecological sanitation approaches. The main advantage of keeping greywater separate from toilet waste water is that the load of pathogens is greatly reduced and therefore greywater is easier to treat and reuse.
When greywater is mixed with toilet water, it is called waste or blackwater and should be treated at a sewage treatment plant or on-site waste facility, which is often a septic system. When it is kept separate, it may open up an attractive decentralized care and reuse option.
Greywater from the kitchen sink contains fat, oil and fat as well as many organic ingredients. It must undergo initial treatment to remove these substances before being thrown into a gray water tank. If this is difficult to apply, it can be redirected to blackwater systems or to existing sewers.
Most greywater is easier to treat and recycle than blackwater, due to lower levels of contaminants. If collected using a separate pipe system from blackwater, domestic graywater can be recycled directly within the home, garden or company and used either immediately or processed and stored. If stored, it should be used in a very short time or it will start to rot because of the organic solids in the water. This type of recycled gray is never safe to drink, but a number of treatment steps can be used to provide water for washing or flushing toilets.
Processing processes that can be used in principle are the same as those used for waste treatment, except that they are usually installed on a smaller scale (decentralized level), often at the household or building level:
- Biological systems such as building wetlands or living walls and bioreactors or more compact systems such as membrane bioreactors which are variations of active sludge processes and are also used to treat wastes.
- Mechanical systems (filtering sand, lava filter systems and systems based on UV radiation)
In wetlands built, plants use contaminants from greywater, such as food particles, as nutrients in their growth. However, salt and soap residues can be toxic to microbes and plant life, but can be absorbed and degraded through wetlands built and water plants such as sediment, haste, and grass.
Reuse
Global water resources are deteriorating. According to a report from the United Nations states that 2.7 billion people will face water shortage problem by 2025, which means almost 1/2-1/3 of the world's total population will be affected by this problem. Reusing wastewater has been a good way to overcome this problem, and reuse of wastewater is also called recycled water or reclamation.
Benefits
The demand for conventional water supply and pressure on waste treatment systems is reduced by the use of greywater. Reusing greywater also reduces the volume of waste that enters the water stream that can be ecologically beneficial. In times of drought, especially in urban areas, the use of seawater in gardens or toilet systems helps achieve some ecologically sustainable development goals.
The potential ecological benefits of greywater recycling include
- Reduce freshwater extraction from rivers and aquifers
- Fewer impacts from septic tanks and maintenance installation infrastructure
- Reduce energy use and chemical pollution from maintenance
- Recharge groundwater
- Nutrition reclamation
- Better surface and ground water quality when preserved by natural purification in the topsoil rather than the resulting water treatment process
In the Southwest and Central America where available water supplies are limited, especially given the rapidly growing population, there is a strong imperative for the adoption of alternative water technologies.
The potential economic benefits of greywater recycling include
- Can reduce water demand, and when people reduce water use, domestic water consumption costs are significantly reduced, while reducing global water resource pressures.
- Can reduce the amount of waste water entering the sewer or the on-site maintenance system.
Security
The use of greywater for irrigation seems to be a safe practice. A 2015 epidemiological study found no additional burden of disease among greywater users who irrigate dry areas. The safety of reuse of greywater as drinking water has also been studied. Some organic micropolutants including benzene are found in greywater in significant concentrations but most pollutants are in very low concentrations. Fecal contamination, peripheral pathogens (eg, skin and mucous tissue), and food-derived pathogens are the three main sources of pathogens in gray water.
Reuse of water in toilets and garden irrigation can produce aerosols. It can transmit legionella disease and bring potential health risks to humans. However, the results of the study indicate that health risks due to greywater reuse either for garden irrigation or toilet flushing are not significantly higher than the risks associated with the use of clear water for the same activity.
Irrigation
Most graywater is assumed to have several blackwater-type components, including pathogens. Greywater should be applied beneath the surface where possible (eg, via droplets over the ground, under mulch, or in a mulch-filled trench) and not sprayed, as there is a danger of inhaling water as aerosols.
In greywater systems, it is important to avoid toxic materials such as bleach, bath salts, artificial colors, chlorine-based cleaners, strong/alkaline acids, solvents, and boron-containing products, which are toxic to plants at high levels. Most cleaning agents contain sodium salts, which can cause excessive soil alkalinity, inhibit seed germination, and destroy soil structures by spreading clay. The soil watered by the greywater system can be altered with gypsum (calcium sulphate) to reduce pH. Cleaning products containing ammonia are safe to use, as plants can use them to obtain nitrogen. A 2010 study of greywater irrigation found no major health effects on plants, and showed sodium buildup strongly dependent on the extent to which greywater migrates vertically through the soil.
Some greywater can be applied directly from the sink to the garden or container field, receiving further care of the soil life and plant roots.
Use of non-toxic and low-sodium soaps and personal care products is recommended to protect vegetation when reusing greywater for irrigation purposes.
Indoor reuse
The recycled gray from the shower and bathtub can be used to flush toilets in most European and Australian jurisdictions and in the jurisdictions of the United States that have adopted the International Plumbing Code.
Such a system can provide a 30% reduction in estimated water use for the average household. The danger of biological contamination is avoided by using:
- Cleaning tank, to remove floating and drowning items
- Intelligent control mechanisms that water the collected if stored long enough to be dangerous; this really avoids filtering and chemical treatment issues
Greywater recycling without treatment is used in certain dwellings for applications where drinking water is not needed (eg, garden and land irrigation, flushing toilets). It can also be used in residence when greywater (for example, from rainwater) is clean enough to start and/or has not been contaminated with non-degradable chemicals such as non-natural soaps (thereby using natural cleaning products instead). It is not recommended to use water that has been in the greywater filtration system for more than 24 hours or bacteria to accumulate, affecting reused water.
Due to limited maintenance technology, treated greywater still contains some chemicals and bacteria, so some safety issues should be observed when using greywater treated around the house.
Hot reclamation
Devices are currently available that capture the heat from residential and industrial greywater, through a process called drainage water draining, greywater heat recovery, or hot water recycling.
Instead of flowing directly to the water heater, the cold water enters the first stream through a heat exchanger where it is heated by the heat from water that flows out of activities such as washing dishes, or bathing. Ordinary household appliances that receive greywater from the shower can recover up to 60% of the heat that should be wasted.
Rule
United States
The government regulation governing the use of domestic graywater for landscape irrigation (diversion for reuse) is still a growing field and continues to gain broader support because the risks and benefits are actually considered and put into a clearer perspective.
"Greywater" (by the definition of pure law) is considered in some jurisdictions to be "waste" (all wastewater including greywater and toilet waste), but in the United States states that adopting the International Pipeline subsurface irrigation and for flushing of toilets, and in countries adopting Uniform Pipes , it can be used in underground sewage fields similar to shallow waste landfills.
Wyoming enables surface and subsurface irrigation and other non-specific greywater uses under the Environmental Department's Department of Environmental policy enacted in March 2010. California, Utah, New Mexico, and several other states allow for true subsurface droplet irrigation with greywater. Where greywater is still considered waste, it is bound by the same regulatory procedures that are applied to ensure well designed septic tanks and effluent disposal systems are installed for old system life and to control the spread of disease and pollution. In the jurisdiction of such a regulation, this usually means a domestic graywater diversion for landscape irrigation is not permitted or discouraged by the expensive and complicated requirements of the approval of the waste disposal system. Broader community greywater diversions that can be trusted for landscape irrigation then experience obstacles and result in widespread reuse of greywater by householders outside and in preference to legal avenues.
However, with water conservation becoming a necessity in a large number of jurisdictions, businesses, political pressures and communities has made regulators seriously reconsider the true risks to actual benefits.
It is now recognized and accepted by more and more regulators that the microbiological risk of reuse of greywater at a single occupancy rate where the inhabitants already have a deep knowledge of greywater is in fact an insignificant risk, when managed well without the need for a burdensome approval process.. This is reflected in the newly-issued Greywater sea water diversion laws and regulations of the New Zealand Government and Energy, and the latest part of the greywater legislation in Montana. At the 2009 Legislative Session, the state of Montana passed a law extending the use of greywater into multi-family and commercial buildings. The Department of Environmental Quality has developed rules and design guidelines for the reuse of greywater systems in all these applications. Existing staff will review the proposed system for new subdivisions in conjunction with the review of all components of other wastewater systems.
The strict permission requirements in Austin, Texas, led to the issuance of only one graywater residential permit since 2010. A working group was formed to streamline the licensing process, and by 2013, the city created a new code that has mitigated the requirements, generating four more permits.
In California, a push has been made in recent years to tackle greywater in connection with the goal of reducing the country's greenhouse gases (see AB 32). Because a large amount of energy (electricity) is used to pump, process and transport drinking water in the country, water conservation has been identified as one of the few ways that California seeks to reduce greenhouse gas emissions.
In July 2009, the California Building Standards Commission (CBSC) approved the addition of Chapter 16A "Non-Drinking Water Reuse System" to the 2007 California Plumbing Code. Emergency regulations allow the greywater reuse system to be submitted to California's Foreign Minister August 2009 and become effective immediately after archiving. Assembly Bill 371 (Goldberg 2006) and Senate Bill 283 (DeSaulnier 2009) directed the California Department of Water Resources (DWR), in consultation with the State Health Service Department, to adopt and comply with CBSC regulations for the State version of Appendix J (renamed Chapter 16 Part 2) of the Uniform Plumbing Code to provide design standards for safe buildings with drinkable and recyclable drinking water systems. November 2009 CBSC unanimously voted to approve the California Dual Plumbing Code that sets statewide standards for drinking and recycling water pipe systems in commercial, retail and office buildings, theaters, auditoriums, condominiums, schools, hotels, apartments, barracks, dormitories, prisons, prisons and reformatories. In addition, the California Department of Housing and Community Development has a greywater standard and DWR has also proposed a double pipe design standard.
In Arizona, greywater is defined as water with a BOD5 content of less than 380Ã, mg/L, TSS & lt; 430 and Fats, Oil, and Grease (FOG) should be less than 75Ã, mg/L. Water Arizona has issued suggestions that people should avoid direct contact with the gray water. Most use of greywater is by underground drip irrigation because irrigation surfaces are not allowed. There are three types of usage in Arizona: up to 400 gpd quota per family (almost 1500 L per day) no permission required for the use of greywater, between 400 and 3000 gpd (1500 and 11,355 L per day, respectively) permit is required and at over 3000 gpd (& gt; 11,355 L per day) was considered a conventional wastewater treatment. Other limitations include limiting contacts, limiting the use of herbaceous food crops, the exclusion of hazardous materials and the effective separation of surface runoff.
The Uniform Plumbing Code, adopted in some areas of US jurisdiction, prohibits the use of greywater indoors.
United Kingdom
Graywater recycling is relatively rare in the UK, largely because the financial costs and environmental impact of primary electricity are very low. The greywater system must comply with the Regulations of BS8525 and Water Fittings to avoid risks to health.
Greywater from a single dump has the potential to be reused on site for decorative irrigation, gardens and lawns, watering toilets. Reuse options include Horizontal flow reed bed (HFRB), Vertical flow reed bed (VFRB), green water recycling system (GROW), Membrane bioreactor (MBR) and Membrane chemical reactor (MCR).
Canada
Although Canada is a water rich country, they also plan to reuse greywater. This may be due to the enormous cost that often increases in traditional large-scale sewage treatment systems in big cities. However, at present, the standards for reuse of greywater are not strict compared to other countries in dry areas.
Australia
Greenwater households from a contaminated site can be reused on site in ornamental gardens and watering lawns, toilet watering and laundry use, depending on the type of greywater and level of care. Some people wisely reuse the gross weight, but others use it worse (without any treatment), such as bathing in a bathtub or simply transferring water to the yard where children and pets can be exposed directly. The Department of Health and Community Services (DHCS) focuses on public health protection and then takes action to control and minimize public health risks associated with reuse of greywater.
Cyprus
The Cypriot government has implemented four subsidized water savings: drilling installations, drilling with WC, installation of hot water circulation system and installation of greywater recycling system.
Jordan
The emphasis on the use of greywater in Jordan has two main goals: water conservation and socio-economic aspects. The Amman Islamic Water Development and Management Network (INWRDAM) in Jordan promotes research on the use of gray water in Jordan. Currently, greywater research in Jordan is funded primarily by the International Development Research Center (IDRC) in Ottawa, Canada, to install and use the greywater system based on the establishment of small wetland systems in private households. The cost of this system is about 500 US dollars per household.
References
Source of the article : Wikipedia
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