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Water Quality and Security
Published in Barry L. Johnson, Maureen Y. Lichtveld, Environmental Policy and Public Health, 2017
Barry L. Johnson, Maureen Y. Lichtveld
The reuse of gray water is an emerging environmental policy issue. Gray water is generally defined as all wastewater generated from household activities except that produced from toilets, which is called “blackwater.” Gray water includes water from dish washers, clothes washers, household wash basins, showers, and bathtubs. Such “waste” can be collected and used for outdoor watering of plants, trees, lawns, and irrigation of crops. The average amount of gray water produced in the U.S. is 40 gallons per day per person, which equates to about 65% of a household’s daily water consumption [99]. This is a significant amount of water that is potentially available for recycling. Gray water is important because several U.S. states are considering its use as a component of water conservation programs. These programs are largely nascent and are in response to shortages of water supplies needed to meet the needs of households, industry, and agriculture. The causes of the shortages vary, but factors include increased human populations, fragile groundwater supplies, greater water demand by industry, and drought conditions. Making maximum use of existing water supplies is an environmental policy that will become increasingly important in many countries including the U.S. as climate changes due to greenhouse GHG emissions continue to appear.
Recreational Environment and Swimming Areas
Published in Herman Koren, Best Practices for Environmental Health, 2017
Graywater is wastewater from drainage from dishwashers, sinks, baths, showers, laundry, and food preparation areas. It may include contaminants such as bleach, nitrates, oil and grease, sodium, suspended solids, bacteria, organic matter, be turbid, have a high pH, high water temperature, and have both a high chemical oxygen demand and biological oxygen demand. It is estimated that the amount of graywater produced is an average of 67 gallons per day per person (different studies give different estimated averages of graywater produced on cruise ships). This was originally potable water (drinking water quality) that has been used for the purposes identified above. Graywater does not include any drainage from toilets, urinals, hospitals, or animal spaces. The graywater goes through special pipes to holding tanks for different sources of the liquid. It may go through gross particle filters or grease traps prior to the holding tanks, depending on the ship, and may be discharged without treatment into the surrounding waters or it may be treated before discharge. The holding capacity aboard ship varies considerably from as little as 5 hours to as much as 90 hours. Except in Alaska, treatment of graywater is not required before discharge. However, it should not be discharged in port or within 12 nautical miles of shore. Untreated graywater from ships may contaminate the surrounding waters.
Options for Onsite Management of Wastewater in Harare, Zimbabwe
Published in Innocent Nhapi, Options for Wastewater Management in Harare, Zimbabwe, 2014
An ideal onsite wastewater management scheme for residential areas, based on the 3-Step Strategic Approach (emphasising on pollution prevention/reduction, and treatment plus reuse), is shown in Fig 5.3. A major factor in this scheme is the control of waste volume and pollution loads at household level. This would reduce the amount of wastewater generated and treated (and the size of the treatment unit), and the produced effluent would be suitable for effective methods of treatment like anaerobic systems (Gijzen, 2001). In this scheme, black/greywater and urine/faeces separation systems are feasible with the other option being combined treatment of all wastewater streams but aimed at reuse close to the source of generation. Source separation is advantageous because it requires little or no water usage in the toilet. It also enhances opportunities for localised direct reuse of waste components (urine, greywater) and a host of technologies are available for this (Lindstrom, 1998; Jeppsson et al., 2002). Greywater comes from laundry, bath, and kitchen, and can be easily collected from waste down-pipes before they discharge into a gully trap. It constitutes about 55% of household wastewater in Harare (Table 5.3). In most cases, greywater could be directly reused for gardening, or it could undergo basic treatment and be used for toilet flushing and car washing.
Designing a greywater treatment system in a highly adaptive urban environment: an ergonomics and human factors observational analysis
Published in Urban Water Journal, 2023
Jonathan Davy, Andrew Todd, Geneviève S. Metson, Andrew Thatcher
The research site was a portion of Setswetla urban informal settlement called ‘Silvertown’, located along the Western bank of the Jukskei River to the North of Alexandria township in Johannesburg, South Africa (Figure 1). Setswetla has an estimated population of 30 000 people living in an area of approximately 1 km2 in low-rise buildings. Community membership is highly transient with people moving in from rural areas to be close to employment (and shelter) opportunities and leaving when those opportunities change. Local government provides limited services such as communal taps for potable water, shared portable toilets, communal dumpsters for solid waste, and some electricity, but ad hoc and ‘illegal’ connections abound. Greywater is disposed on-site either onto pathways or into makeshift ditches or channels. In this context, greywater often becomes mixed with blackwater from broken sewers and other waste streams where it flows openly through the community, without treatment, towards the Jukskei river. Greywater refers to wastewater from washing and other household chores like laundry and cleaning floors (Maimon et al. 2010; Oteng-Peprah, Acheampong, and DeVries 2018). Although usually less of a health risk than blackwater, greywater in low-middle income countries may still contain problematic pathogens and pollutants given residents may not always have access to a safe way to dispose of their blackwater (Maimon et al. 2010; Shaik and Ahammed, 2020).
Impact of greywater on germination and physiological responses of Triticum aestivum L. HD 2967 in soil amended with poultry biochar
Published in Environmental Technology, 2023
Rekha Kumari, Rozi Sharma, Neeraj Kumar Sharma, Deepak Pant, Piyush Malaviya
The soil used in the study was alkaline, this alkalinity along with nutrients decreased with time, and the decline was prominent for 50% GW irrigation. Accordingly, greater nutrients were found in soil with 100 per cent GW irrigation particularly, for soil and 10 g biochar amendments. The pH between 6 and 7.5 is considered optimum for plant and soil microorganisms, care is needed when soil pH is more than 8.2 or drops below 6. As GW irrigation resulted in higher EC and soil pH; therefore, regular monitoring of GW irrigated soil is necessary and if soil pH is above 7.5 it needs to be neutralized by the addition of gypsum. Increasing the pH of alkaline soil may have an impact on nutrient solubility and bioavailability [24]. It causes an accumulation of salts [24], which can be prevented by repeatedly backwashing with freshwater which leads to the dilution of salt content. The data revealed that fewer variations were observed on the 14th day after sowing as compared to the initial day. Greywater has proven to be a useful substitute for freshwater, especially in non-potable uses such as toilet flushing and irrigation.
Application of activated carbon from banana stem waste for removal of heavy metal ions in greywater using a Box–Behnken design approach
Published in Environmental Technology, 2020
Sarva Mangala Praveena, Umer Rashid, Suraya Abdul Rashid
Greywater corresponds to domestic wastewater produced in bathtubs, showers, hand basins and laundry machines which constitute about 75% of total domestic wastewater production. In addition, greywater accounts for 65% of the total water usage amount in any household [1]. Climate change impacts, long dry periods and water resource scarcity were the driving forces behind the increased interest in greywater treatment and reuse options. Greywater treatment in domestic wastewater involves a great deal of investment in long sewage pipelines, sophisticated technologies and operational cost with huge amounts of freshwater supply for the treatment process. On-site greywater treatment at the household level is receiving increasing attention due to factors such as low cost and lower pollutant concentrations compared to domestic wastewater that can be treated using low cost technologies [2]. It is important to note that treated greywater can be used for non-potable intentions such as irrigation, washing and toilet flushing [3,4].