Greywater Reuse For Irrigation Research Articles

Greywater characterization and generation rates in a peri urban municipality of a developing country

The quantity and quality of combined greywater from houses with in-house water supply and houses that rely on external sources of a peri-urban area in a developing country were determined. Data for quantity of greywater was collected from 36 households while 180 samples of greywater were collected from 60 households between December 2016 and February 2017. The results indicate that, average water consumption from households with in-house access was 82.51 ± 12.21 Lc−1d−1 while households which rely on external sources was 36.64 ± 4.31 Lc−1d−1 with return factors of 74.16% and 88.57% respectively. Quality analysis also showed significant differences between greywater from the two sources with most of the quality parameters exceeding the regulatory limit. The ratio between biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) ranged between 0.22 and 0.59 for greywater from in-house sources and 0.23–0.62 for external sources indicating low biodegradability of the greywater. The nutrients recorded exceeded the trigger levels for eutrophication while significant levels of microorganisms such as E. Coli and Salmonella spp. were also detected in both streams. Direct reuse of greywater for irrigation was found to be unsuitable based on the salinity and sodium hazard analysis. Principal component analysis of the data indicated that the characteristics of the combined greywater in the study area is influenced by cooking and cleaning practices, personal hygiene, biodegradability, frequency of water use before disposal and sanitary practices in the bathroom. The greywater discharged is detrimental to the environment and poses a health risk to humans and livestock. There is therefore the need for authorities involved to prioritize greywater management and treatment in peri-urban areas of developing countries.

The Potential of a Low Cost Technology for The Greywater Treatment

Greywater (GW) is household wastewater effluent originating from baths, showers, kitchen and hand wash basins and laundry and constitutes 50-80% of indoor household water use. It represents water that can potentially be intercepted at the household level for use. In Kenya, GW use is practiced on an informal basis to supplement irrigation water, either in urban gardens in middle to upper income suburbs or in food gardens in lower income informal, periurban and rural areas. However, the reuse of greywater for irrigation without any significant pre-treatment poses a potential risk to both human and environmental health due to microbial and chemical contamination. This study investigated the potential of a low cost greywater treatment (GWT) system for safe greywater reuse by households. The system comprises of discrete units of barrels that allows for filtration, flocculation, sedimentation and disinfection. GWT system produced water with both pH and electrical conductivity suitable for irrigation according to WHO guidelines. It was also efficient at eliminating Salmonella sp. and reducing total coli form in composite greywater from households in Homa Bay after the effluent was disinfected with commercial disinfectant, sodium hypochlorite (NaOCl). The cleaned greywater had a total coli form count (2.5x10 6 cfu/100 ml) comparable to 0->2.4 � 10 6 cfu/100 ml obtained when greywater was treated using an expensive biological aerated filter (BAF). Fecal coli form counts (2.1� 10 2 cfu/100 ml) compare well with 10 3 cfu/100 ml provided in WHO guidelines for public parks and crops likely to be eaten uncooked. The treatment had no effect on dissolved oxygen, pH, salinity and electrical conductivity. The study concludes that the GWT system can be a sustainable and promising low cost low technology treatment system that can be run and maintained by unskilled operators.

Safe on-Site Reuse of Greywater for Irrigation - A Critical Review of Current Guidelines

Reuse of greywater for landscape irrigation can significantly reduce domestic water consumption. Alongside its benefits, there are potential drawbacks to greywater reuse, raising legitimate concerns about the impact on human and environmental health. In this review, a risk assessment framework is used to assess the adequacy of different regulations to ensure safe and long-lasting, onsite greywater reuse for irrigation. Existing regulations from around the world are assessed along with a standardized evaluation of measures taken to protect public and environmental health. In most cases, human health considerations currently dominate regulatory strategies, while environmental risks are either ignored or underrepresented. A distinction between single and multiple households was found to be a fundamental component of the regulations which often lead to approved utilization of untreated greywater among single households. We concluded that the use of untreated greywater is not recommended, especially in multihousehold systems as it may compromise public health, with single household systems posing more likely risks to the environment. Existing rules to control greywater use should be further revised toward the establishment of a more advanced regulatory system which can avert the salient potential risks associated with greywater reuse, while exploiting the enormous potential of this alternative water resource.

Reuse of greywater for irrigation around homes in Australia: Understanding community views, issues and practices

We examined people's views on a number of water issues and their motivation, practices and concerns about greywater reuse for irrigation of around homes. Survey participants (275) from different socio-economic background from 125 suburbs in the Western Sydney region, Australia took part in the study. Regardless of their age and gender, when asked which was the most important issue regarding water in their region from a prescribed list, the majority of participants identified water quality as the most important and availability without water restriction as the least important. About half of the participants reused greywater regularly or at some time during the last few years. The cost of plumbing and health risks to people, plants and soil are critical issues for greywater reuse and need attention. For the reusing widely and sustainably, there is a need for easily accessible, user-friendly information packages to create ‘greywater reuse literacy’ in the community.

Greywater reuse for irrigation: Effect on soil properties

A controlled study of the effect of greywater (GW) irrigation on soil properties was conducted. Containers of sand, loam and loess soils were planted with lettuce, and irrigated with fresh water, raw artificial GW or treated artificial GW. Greywater was treated using a recirculating vertical-flow constructed wetland. Soil samples were collected every 10 days for the 40-day duration of the study, and plant growth was measured. Soils were analysed for physicochemical and biological parameters to determine changes caused by the different treatments. It was demonstrated that raw artificial GW significantly increased the development of hydrophobicity in the sand and loam soils, as determined by water droplet penetration time. No significant changes were observed for the loess soil under all treatments. Observed hydrophobicity was correlated with increased oil and grease and surfactant concentrations in the soil. Zeta (ζ) potential of the soils was measured to determine changes in the soil particle surface properties as a result of GW irrigation. A significant change in ζ-potential (less negative) was observed in the raw artificial GW-irrigated sand, whereas no difference was observed in the loam or loess. Soils irrigated with fresh water or treated GW exhibited no increase in hydrophobicity. Fecal coliform bacteria were absent or < 10 CFU g − 1 in soils irrigated with fresh water or treated GW, but at least 1 order of magnitude higher in raw artificial GW irrigated soils. Only in the last sampling event and only for the loess soil was plant growth significantly higher for fresh water irrigated vs. raw or treated GW irrigated soils. This study demonstrates that treated GW can be effectively irrigated without detrimental effects on soil or plant growth; however, raw GW may significantly change soil properties that can impact the movement of water in soil and the transport of contaminants in the vadose zone.