Greywater Reuse Research Articles

Remarks on sustainable disposal and potential reuse of greywater in an informal urban settlement, Cape Town, South Africa

Background The disposal of greywater is a challenge for informal urban settlements that do not have a reticulation system to collect the wastewater they generate. Greywater, which includes domestic wastewater, represents a potential resource that can alleviate water stress if efficiently managed. This study aimed to provide sustainable disposal and potential reuse of greywater produced using informal settlements in Cape Town, South Africa. Greywater has the potential to contribute significantly to food security in such settlements by providing a source of both irrigation water and toilet flushing. Methods A combination of desktop research and interviews was employed to gather and analyze the data. A total of 69 questionnaires were administered in the study, and greywater management practices were investigated. Results The findings showed deficiencies in the sustainable disposal of greywater from households. To understand the volumes of greywater generated from a household, a model has been proposed in the study, as there has been a lack of focus on making predictions that quantify the volume of greywater recovered from these households. Conclusions In the context of sustainable development, water management, and considering the scarcity of water resources, particularly in semi-arid regions, the use of treated greywater is an alternative method that can reduce the burden of withdrawals. The study has demonstrated that socio-economic status and education level has reciprocal outcomes on the communities’ understanding of environmental issues. Eliminating inappropriate disposal and providing means to sustainable reuse of greywater effluent is the key.

Greywater recycling for diverse collection scales and appliances: enteric pathogen log-removal targets and treatment trains

In light of increasingly diverse greywater reuse applications, this study proposes risk-based log-removal targets (LRTs) to aid the selection of treatment trains for greywater recycling at different collection scales, including appliance-scale reuse of individual greywater streams. An epidemiology-based model was used to simulate the concentrations of prevalent and treatment-resistant reference pathogens (protozoa: Giardia and Cryptosporidium spp., bacteria: Salmonella and Campylobacter spp., viruses: rotavirus, norovirus, adenovirus, and Coxsackievirus B5) in the greywater streams for collection scales of 5-, 100-, and a 1000-people. Using quantitative microbial risk assessment (QMRA), we calculated LRTs to meet a health benchmark of 10-4 infections per person per year over 10’000 Monte Carlo iterations. LRTs were highest for norovirus at the 5-people scale and for adenovirus at the 100- and 1000-people scales. Example treatment trains were designed to meet the 95% quantiles of LRTs. Treatment trains consisted of an aerated membrane bioreactor, chlorination, and, if required, UV disinfection. In most cases, rotavirus, norovirus, adenovirus and Cryptosporidium spp. determined the overall treatment train requirements. Norovirus was most often critical to dimension the chlorination (concentration × time values) and adenovirus determined the required UV dose. Smaller collection scales did not generally allow for simpler treatment trains due to the high LRTs associated with viruses, with the exception of recirculating washing machines and handwashing stations. Similarly, treating greywater sources individually resulted in lower LRTs, but the lower required LRTs nevertheless did not generally allow for simpler treatment trains. For instance, LRTs for a recirculating washing machine were around 2-log units lower compared to LRTs for indoor reuse of combined greywater (1000-people scale), but both scenarios necessitated treatment with a membrane bioreactor, chlorination and UV disinfection. However, simpler treatment trains may be feasible for small-scale and application-scale reuse if: (i) less conservative health benchmarks are used for household-based systems, considering the reduced relative importance of treated greywater in pathogen transmission in households, and (ii) higher log-removal values (LRVs) can be validated for unit processes, enabling simpler treatment trains for a larger number of appliance-scale reuse systems.

Cost and Benefit Analysis of Different Buildings Through Reuse of Treated Greywater

The fact that the impacts of climate change cannot be prevented in the short term has increased the importance of climate change adaptation activities, and many national and international studies have been initiated in this regard. Greywater reuse (GWR) activities have become important methods recommended by the Intergovernmental Panel on Climate Change (IPCC) for adaptation to climate change. This study selects GWR from 3 different real typologies, a hotel, a residential building, and an industrial plant planned in Izmir Province of Türkiye, to design greywater systems followed by cost-benefit analyses. The applicability of GWR systems in these typologies has been analyzed, and comparisons have been made. GWR systems at the project design stage eliminate the need for installation modifications. Therefore, it is concluded that new buildings should be designed to integrate these alternative water resource systems. Recovered water through the installation of GWR systems is recommended to be used as flushing water, and the excess for garden irrigation, car washing and cleaning. The payback periods were calculated as 12 years for the hotel and industrial plant and 6 years for the residential building. The water savings were calculated as 46% for the hotel, 44% for the residential building, and 29% for the industrial plant. The results put forth the feasibility of this alternative water resource.

Long-term evaluation of soil-based bioelectrochemical green roof systems for greywater treatment

Water scarcity has generated the need to identify new sources. Due to its low organic contaminant load, greywater reuse has emerged as a potential alternative. Moreover, the search for decentralized treatment systems in urban areas has prompted research on using green roofs for greywater treatment. However, the performance of organic matter removal is limited by the type of substrate and height of the growing media. Bioelectrochemical systems (BESs) improve treatment performance by providing an additional electron acceptor (the electrode). In this study, nine reactors under three different conditions, i.e., open circuit (OC), microbial fuel cell (MFC), and microbial electrolysis cell (MEC), were built to evaluate the treatment of synthetic greywater in a substrate-growing medium composed of perlite and coconut fiber and operated in batch-cycle mode for 397 days. The results suggested that using BESs enables greywater treatment and the removal of pollutants to levels that allow their reuse for irrigation. Furthermore, electrical conductivity was reduced from 732.4 ± 41.2 μS/cm2 in OC to 637.32 ± 22.73 μS/cm2 and 543.15 ± 19.69 μS/cm2 in MEC and MFC, respectively. The soluble chemical oxygen demand in the latter treatments reached 76% removal, compared to levels above the OC, which only reached approximately 67%. Microbial community analysis revealed differences, mainly in the cathodes, showing a higher development of Flavobacterium, Azospirillum, and Zoogloea in MFCs, which could explain the higher levels of organic matter removal in the other conditions, suggesting that the BES could produce an enrichment of beneficial bacterial groups for treatment. Therefore, implementing BESs in green roofs enables sustainable long-term greywater treatment.

A sustainable design approach of a mega hostel: a study based at NIT, Srinagar, Kashmir, India

ABSTRACT In a sustainable building design, energy, water and resource optimization are key considerations, along with minimizing impacts on the ecology and environment. In this case study, water-related issues are considered from a sustainability perspective. The main objective of this study is to provide a sustainable design for a mega-hostel at the National Institute of Technology (NIT) Srinagar, with the aim of achieving an eco-friendly design which minimizes its dependence on external sources of energy. Rainwater harvesting, greywater reuse and the installation of a biogas plant are the three main techniques considered in this project. Rainfall data were collected and water demands for the mega-hostel and greywater produced by the mega-hostel were estimated. Potential rainwater harvesting, dimensions of a storage tank, first flush volume, discharges and dimensions of gutters have been calculated in this study. Greywater quantity has been calculated and a membrane bioreactor (MBR) to treat greywater is suggested, because it is space-optimized. Dimensions of a biogas plant and the quantity of gas released have also been estimated based on the amount of food waste generated by the mega-hostel.

Assessing homeowners’ awareness of green technologies in residential housing development: evidence from Ghana

PurposeUsing and promoting green technologies in residential buildings might be a far more practical strategy for developing a sustainable built environment. The primary goal of this study is to examine homeowners' knowledge and awareness of the different green technologies and concepts that can be adopted to improve the quality of their homes.Design/methodology/approachThe study employed a sequential mix technique methodology in order to accomplish its goal. A total of 156 respondents were chosen for a survey within the research areas using a simple random sample approach, while interviewees were chosen using a purposive sampling approach methodology. Descriptive and inferential statistics as well as content analysis were used to analyze the quantitative and qualitative data, respectively.FindingsThe findings indicate that homeowners have moderate knowledge of green technologies. It was also evident that print and electronic media are excellent at capturing and reaching a diverse range of homeowners interested in learning about sustainable development issues. Furthermore, the top three green technologies that most homeowners are aware of are using local materials over imported materials, grey water reclaiming and reuse technology and solar water heating technology. Subsequently, the homeowners in the three communities have differing opinions about the majority (82%) of the green technologies examined.Originality/valueThe findings will serve as a useful guide to assist practitioners and policymakers in implementing appropriate methods to integrate green technologies into housing projects and subsequently encourage their adoption.

Exploring household water conservation methods in rural South Africa: a case of the Mbhashe and Mnquma local municipalities

Amidst the persistent drought disaster declared in 2015, the Amathole District Municipality grapples with severe water scarcity issues, particularly affecting local municipalities such as Mbhashe and Mnquma. Consequently, households in these areas confront the challenges of unreliable and contaminated water sources, prompting them to adopt water conservation measures to mitigate shortages. This study investigates the efficacy of water conservation methods among rural households in these drought-affected regions. It identifies associated challenges and potential interventions to ensure access to clean and dependable water. Employing a mixed methods approach, the study examines household water conservation practices through narrative analysis and descriptive statistics of survey data. Findings reveal that storing water in drums, containers, and tanks is the most prevalent conservation method, alongside measures like greywater reuse, lifestyle adjustments, and rainwater harvesting. With financial constraints and infrastructural limitations hindering broader adoption, the study found water conservation to be a challenge among the households as a minority (7.8%) of respondents adopted multiple water conservation strategies. In comparison, most respondents (73.6%) could only afford to practice one water conservation strategy at a time, and others (18.6%) had no conservation strategies. Drought conditions, lack of infrastructure, poverty, and attitudinal factors are primary barriers to effective water conservation. The study underscores the need for municipal-level initiatives to enhance water sources and advocates for increased investment in education, awareness campaigns, and policy interventions to address rural communities’ water scarcity challenges.

Treatment of greywater coming from a food court using adsorption and advanced oxidation processes

The increase in the demand for water has recrudesced water scarcity in several places of the world, which has been intensified by the lack of rainfall, generating a water crisis, being very important to evaluate the treatment to allow the reuse of greywater. This is the first study focused on the removal of pollutants present in greywater using a pretreatment system based on ozone and solar irradiation. A series of treatments were addressed to evaluate the depuration of greywater coming from the dishwashing of a university dining hall. Notable findings of the study include several aspects such as a very high colour removal using sedimentation and, filtration and flotation process, with an overall colour removal of 91.8 %. The adsorption process removed a higher amount of surfactants with dried compost as adsorbent compared to fly ash or zeolite, with surfactant removal rates of 50.8 %, 7.8 %, and 9.0 %, respectively. Eliminating oil and grease from the greywater was studied with a solar photoreactor coupled with an ozonation process and configured in different ways. When ozone was incorporated into the vertical ozonation tube, and greywater was pumped to mix it with the ozone gas to pump the resulting mix to the borosilicate tube, oil and grease removal was 84.1 %. These treatment processes offer an effective solution for removing pollutants present in greywater; however, further studies and optimisation of operational conditions are required to enhance the efficiency of the treatment.

Assessing greywater characteristics in the sahel region and perception of the local population on its reuse in agriculture

Research on greywater reuse in water stressed areas is in full swing. However, the perception of greywater reuse is one of the least researched areas in West Africa, particularly in Sahelian countries. This study aimed to fills a significant gap in the existing literature, which has largely ignored the specific socio-demographic contexts of developing countries in the Sahelian regions. The study involved in-depth interviews with 240 rural households and the collection of 40 greywater samples in four locations for laboratory analysis. The survey focused on greywater management and household perceptions of greywater reuse in agriculture. The analyses focused on determining the physico-chemical and microbiological parameters of greywater collected from households. The results showed that over 80 % of households discharged greywater into the natural environment without prior treatment. The majority of respondents were aware that poor greywater management poses a health risk. The results also showed an association between locality, gender, education level and perceptions of poor grey water management. Respondents were willing to accept the reuse of greywater in agriculture, to consume irrigated vegetables and to install a greywater treatment system. The quality analysis showed that the greywater was not in compliance with the legal discharge limits. This study highlights that in order to promote sustainable greywater management practices within households, it is important to design effective greywater treatment systems that meet the needs of the target population. Awareness campaigns, education and training programmes on wastewater management could also be established.

Economic Feasibility of Rainwater Harvesting and Greywater Reuse in a Multifamily Building

Economic Feasibility of Rainwater Harvesting and Greywater Reuse in a Multifamily Building

Egyptians awareness towards domestic water conservation and reuse

Egypt's population growth has led to the expansion of new cities and urban communities in the desert areas near the Delta and Nile Valley. However, providing fresh water to these cities is a costly affair due to their distance from the Nile River, high elevation, and excessive water consumption by residents. To address this issue sustainably, renewable sources of water must be found, and existing resources must be managed efficiently. Public acceptance is crucial for success, so a survey was conducted in four governorates (Cairo, El-Minya, Assuit, and Sohag) to assess public awareness of water-saving practices and treated greywater reuse for non-potable options. The results indicated that women have a lower level of awareness of water scarcity issues compared to men. Only 53 % of female participants were aware of the problem, while 75.2 % of male participants were aware. Similarly, only 79.5 % of female participants were aware of the importance of water conservation compared to 92.3 % of male participants. This lack of awareness has resulted in negative impacts on their water consumption habits, willingness to adopt water conservation measures, and their willingness to reuse treated greywater. Shockingly, only 50 % of individuals between the ages of 18 and 25 were aware of the issue of water scarcity. Furthermore, only 25 % of participants with primary education were aware of the issue of water scarcity and the importance of conserving water. There is a strong correlation between knowledge of the water crisis issue and willingness to adopt water conservation measures and reuse treated greywater. Participants were most accepting of reusing greywater for car washing at 66.5 %, followed by irrigation of green spaces at 64.5 %, and then for toilet flushing at 33.5 %. About 44.2 % of participants believed that the main challenge in reusing treated greywater was concerns about water quality.

Low-Cost Grey Water Treatment System Design And Treatability Studies In Relation To Recycling And Reuse In Rural Area of Angul District of Odisha

As global water scarcity intensifies, there is a growing need for sustainable water management solutions, particularly in rural areas where access to clean water is often limited. This study focuses on the development of a low-cost greywater treatment system tailored for rural settings, emphasizing the recycling and reuse of greywater. The research encompasses the design, implementation, and treatability studies of the proposed system, aiming to provide an affordable and effective solution for improving water sustainability in resource-constrained communities. The designed greywater treatment system incorporates cost-effective technologies and locally available materials to ensure its feasibility in rural contexts. The treatability studies explore the system's efficiency in removing contaminants commonly found in greywater, evaluating its potential to meet water quality standards suitable for various non-potable applications. Emphasis is placed on the system's adaptability to local conditions, promoting community engagement and ownership for long-term sustainability. By addressing the unique challenges faced by rural areas, this research contributes to the broader goal of achieving water security through decentralized, affordable, and environmentally conscious greywater treatment solutions. The findings from this study can inform policymakers, engineers, and local communities on practical approaches to enhance water quality, reduce environmental impact, and promote water recycling and reuse in rural settings.

Synthetic greywater treatment using a scalable granular activated carbon bioelectrochemical reactor

Greywater reuse has emerged as a promising solution for addressing water shortages. However, greywater needs treatment before reuse to meet the required water quality standards. Conventional wastewater treatment technologies are unsuitable for recreating highly decentralized domestic greywater. This study evaluated bioelectrochemical reactors (BERs) with granular activated carbon (GAC) as a sustainable alternative for developing decentralized and low-cost biological treatment systems. BERs using GAC as the anode material and conventional GAC biofilters (BFs) for synthetic greywater treatment were operated in batch mode for 110 days in two stages: (i) with polarized anodes at −150 mV vs. Ag/AgCl and (ii) as a microbial fuel cell with an external resistance of 1 kΩ. Anode polarization produced an electrosorption effect, increasing the ion removal of the BERs. Power production during the operation and cyclic voltammetry tests of the extracted granules revealed electrochemically active biofilm development on the BERs. Although low power density (0.193 ± 0.052 µW m−3) was observed in BERs, they showed a similar performance in sCOD removal (BER = 91.6–89.6 %; BF = 96.2–93.2 %) and turbidity removal (BER = 81–82 %; BF = 30–62 %) to BFs that used 50 % aeration. Additionally, scanning electron microscopy of sampled granules showed higher biomass formation in BER granules than in BF granules, suggesting a higher contribution of sessile (vs. planktonic) cells to the treatment. Thus, the results highlight the synergistic removal effect of the GAC-based BER. The scalable design presented in this study represents a proof-of-concept for developing BERs to use in decentralized greywater treatment systems.

The Maharashtra River Basin's Flood-Drought-Water Scarcity Nexus

<p>India's droughts and floods, which have affected 8 million hectares yearly since the 1950s, make future adaptation and mitigation plans necessary, as well as an awareness of potential changes. In order to address the growing issues of flood and drought events in urban settings, the study emphasizes the importance of comprehensive water management strategies that ensure both routine water needs and severe event readiness. This study article recommends including drought and flood considerations in building codes and urban planning regulations to boost urban water resilience. The paper provides workable solutions for developing water-sensitive urban design, rainwater collecting, greywater reuse programs, and decentralized water management systems through a collection of case studies and strategy models. It also emphasizes the importance of teaching the population about the dangers of droughts and floods, water conservation methods, and emergency response procedures. The recommendations place a lot of emphasis on the need for a variety of policies that encourage cooperation between stakeholders, including local and state governments, business owners, community leaders, and experts. The policy recommendations include requests for green infrastructure, building standards for flood-resistant homes, water conservation requirements, and climate-responsive legislation, among other subjects. By encouraging sustainable water use behaviors, these concepts aim to increase urban resilience and make cities better prepared to mitigate the consequences of drought and flooding. These recommendations can aid local and state governments in creating a culture of preparedness for catastrophes, protecting communities, and fostering urban water resilience. This case study looks at the intricate relationships between a specific Maharashtrian river's floods, droughts, and water scarcity.</p>

A Baseline Study of Bacterial Pathogens in Greywater Samples in Jordan Using Ribotyping

As Jordan advances in an attempt to promote greywater reuse, it is important to investigate the composition of bacteria in these new sources. To evaluate the presence of enteric pathogens in greywater, a pilot study investigating enteric pathogens in household washing machines and kitchen sink effluents from residential premises was conducted. In the culture-dependent method, bacteria were identified after using Sanger sequencing of 16S rRNA. Bacteria in the phylum Proteobacteria have been found to be the most abundant phyla, which may indicate that they play an important environmental role and might be representative of adaptation to different environments. Klebsiella sp. and Pseudomonas sp. were the two major genera found in this study and accounted for 78.57% of the total isolates. This is the first investigation of enteric pathogens in household washing machines and kitchen sink effluents in Jordan. To my knowledge, no study has identified the microbial hazards associated with greywater reuse in Jordan yet. Additional research with more adequate methodology is needed to assist our findings.

Assessment of Greywater Reuse in a University Building in a Hyper-Arid Region: Quantity, Quality, and Social Acceptance

Since Tacna is a hyper-arid region, greywater is a potential alternative water source. This study aimed to quantify and characterize greywater in a university building with 732 students, as well as assess their perception of greywater reuse. Water meters were used to calculate greywater quantity. To assess untreated greywater quality, physical–chemical and microbiological parameters were analyzed. Questionnaires were used to measure students’ acceptance regarding greywater reuse using a Likert scale. The greywater quantity recorded in this study was 426.85 L/d, which is less than reported in previous global research. The greywater quality showed relatively low values regarding physical–chemical parameters; however, microbial contamination was higher compared to international permissible limits for wastewater reuse. Furthermore, it was found that the generated greywater has little biodegradability (0.38). Students disclosed a lower acceptance of reusing untreated greywater compared to a 77.05% acceptance of reusing treated greywater for green areas. According to the greywater characterization, biological treatment will not be enough to ensure environmental protection and user health; thus, physical–chemical treatment will also be needed. The produced greywater quantities would generate a 12.67% water saving if used for toilet flushing. The greywater volume fulfills the whole demand for watering green areas or green roofs. Students would assent to the reuse of treated greywater.

Operation and Performance of The Lab and Pilotscale Greywater Treatment Systems: Biochar and Gravel Use in South Africa

Water security in South Africa depends on natural and artificial water sources such as rivers, lakes, rainwater harvesting, boreholes, dams, desalination, the importation of water from nearby countries, and wastewater treatment plants. The primary input to these water resources is rainfall which is estimated to be around 492 mm per year and is half of the world average (985 mm per year) due to climate change impacts. This study encourages the treatment and reuse of greywater as an additional water source for non-potable purposes such as toilet flushing and irrigation. The performance of the Laboratory (Lab)-scale Gravel Filter Towers (GFTs) was evaluated concurrently with the Pilot-scale system for remediation of the microbiological and physicochemical constituents in greywater which was sampled from separate single-households for both systems. The highest removal efficiency of faecal coliforms by the GTFs was 92.89 ± 93.39 % while the Pilot-scale exhibited a removal efficiency of 21.51 ± 12.47 %. The systems showed partial removal of microbiological, chemical, nutrient, and physical constituents, indicating that further analysis and improvements are required before decentralization. The GFTs could be improved by the addition of a biochar filter while the pilot-scale systems require fresh treatment materials monthly to avoid clogging and leaching of biofilms to the final collection tank. Further analysis could involve the profiling of the microbial communities using metagenomic techniques which may provide insight into the biochemical functioning (bioremediation, quorum sensing, and pathogenicity) of the system.

Heterogeneous Antibiotic Resistance Gene Removal Impedes Evaluation of Constructed Wetlands for Effective Greywater Treatment.

Microorganisms carrying antimicrobial resistance genes are often found in greywater. As the reuse of greywater becomes increasingly needed, it is imperative to determine how greywater treatment impacts antimicrobial resistance genes (ARGs). Using qPCR and SmartChip™ qPCR, we characterized ARG patterns in greywater microbial communities before, during, and after treatment by a recirculating vertical flow constructed wetland. In parallel, we examined the impact of greywater-treated irrigation on soil, including the occurrence of emerging micropollutants and the taxonomic and ARG compositions of microbial communities. Most ARGs in raw greywater are removed efficiently during the winter season, while some ARGs in the effluents increase in summer. SmartChip™ qPCR revealed the presence of ARGs, such as tetracycline and beta-lactam resistance genes, in both raw and treated greywater, but most abundantly in the filter bed. It also showed that aminoglycoside and vancomycin gene abundances significantly increased after treatment. In the irrigated soil, the type of water (potable or treated greywater) had no specific impact on the total bacterial abundance (16S rRNA gene). No overlapping ARGs were found between treated greywater and greywater-irrigated soil. This study indicates ARG abundance and richness increased after treatment, possibly due to the concentration effects of the filter beds.

Examining the efficacy of the legal framework governing the management of greywater in South Africa's informal settlements.

The management of greywater and sanitation in South Africa's urban informal settlements is a pressing concern. This review critically examines the legal framework that governs greywater management in South Africa's informal settlements, aiming to shed light on the existing regulations, gaps, and opportunities for sustainable greywater reuse. By scrutinizing the legal framework, the review identifies gaps and challenges in the regulatory environment, including inconsistencies, lack of clarity, and limited enforcement mechanisms. It explores the potential for international best practices to inform possible amendments to the existing legal framework. This was a quantitative research design utilizing a cross sectional survey model. Questionnaires were administered electronically to a sample of 17 municipal leaders from the City of Tshwane, City of Johannesburg and Buffalo City municipalities whose responsibilities were on water management. Descriptive statistics were employed in analysis of the data. Outcomes were reviewed against the alignment or the lack thereof with the SANS 1732:201x standards. This paper underscores the critical need for a coherent and robust legal framework to support responsible greywater management in South Africa's informal settlements. The paper's insights contribute to the ongoing discourse on water governance, shedding light on the pathways toward a more equitable water future.

Impact of urbanism on source separation systems: A life cycle assessment

This study aims to assess the effect of different urban configuration regarding the choice of wastewater management of the district with source separation systems. Understanding this link can guide researchers, and also urban actors, in order to choose the best source separation solution to implement in a specific urban configuration.For this purpose, an integrated modelling approach was used to model the district with different types of urban planning, the water resources recovery facility (WRRF) and create a life cycle inventory to carry out a life cycle assessment (LCA). Six different urban configurations were tested with three different source separation scenarios and compared with an advanced WRRF with high level of nutrients and organic matter recovery.This study concludes that urine source separation is beneficial compared to advanced WWRF for all the urban configurations. Sewer construction was identified as the main contributor to environmental impact for the low-density configuration (pavilions), limiting the benefits of source separation in this urban settlement. Blackwater separation with a decentralised treatment is only beneficial for high densely populated area. Treatment of blackwater and greywater for reuse, has greater impact than reference scenario, in all urban configurations, due to high energy consumption for greywater treatment. Future research should therefore explore technical solutions for limiting the energy consumption.