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While phytoremediation has been widely employed for greywater treatment, this system suffers from the transfer of considerable amounts of surfactants to the aquatic environment through partially treated effluent and/or exhausted plant disposal. Hence, this study focuses on greywater phytoremediation followed by recycling the spent plant for preparing an adsorbent material used as post-treatment. P. crassipes was used to operate a phytoremediation unit under 23 °C, 60% relative humidity, plant density (5–30 g/L), dilution (0–50%), pH (4–10), and retention time (3–15 days). The optimum condition was 12.7 g/L density, 34.0% dilution, pH 8.4, and 13 days, giving chemical oxygen demand (COD), surfactant, and NH4-N removal efficiencies of 94.62%, 90.45%, and 88.09%, respectively. The exhausted plant was then thermally treated at 550 °C and 40 min to obtain biochar used as adsorbent to treat the phytoremediation effluent. The optimum adsorption process was biochar dosage of 1.51 g/L, pH of 2.1, and 137 min, providing a surfactant removal efficiency of 92.56%. The final discharge of this phytoremediation/adsorption combined process contained 8.30 mg/L COD, 0.23 mg/L surfactant, and 0.94 mg/L NH4+-N. Interestingly, this approach could be economically feasible with a payback period of 6.5 years, 14 USD net present value, and 8.6% internal rate of return. NOVELTY STATEMENT: The research succeeded in treating greywater by phytoremediation followed by recycling the exhausted P. crassipes plant to prepare an adsorbent material used in the post-treatment phase, giving an economically feasible scenario with 6.5-year payback period. [ABSTRACT FROM AUTHOR]

This article explores the concept of irrigated urban agriculture (IUA) in rapidly urbanizing cities in the Global South. IUA plays a crucial role in supplying fresh food, particularly vegetables, to urban areas and contributes to community well-being by creating green spaces. However, IUA practices are often contested and ignored by regulatory authorities. The article argues for a contextual understanding of IUA practices and policies to promote sustainable urban water management and food security. It also discusses the complexities and challenges surrounding informal urban agriculture and emphasizes the need for governance approaches that recognize the dynamics of bottom-up development and address societal concerns. Additionally, the document highlights the importance of policies and institutions that support IUA and facilitate access to resources, as well as collaboration between different sectors and stakeholders. Overall, the article calls for a paradigm shift in governance arrangements to fully integrate IUA into formal urban development. [Extracted from the article]

A dynamic model, fed with time-variant inputs, of the entire water urban system, coupled with Life Cycle Assessment (LCA) and Life Cycle Costing (LCC), was developed and applied to perform water balance analysis and to assess the environmental and economic aspects of water reuse. Six scenarios using different water sources potable water, rainwater, greywater, and treated wastewater were compared for a future Model City under typical Israeli conditions. The integrated dynamic simulation-LCA-LCC approach considers demands for several water resources and their availability, contains several feedback loops in the water system, and can be applied to any case study. Finally, the combined simulation-LCA-LCC was embedded into an optimisation framework. Results indicate that using treated greywater or treated wastewater for non-potable uses were the most economical scenarios. Business-as-usual scenario, where all urban water functions use potable water, displays the largest negative environmental impacts in all categories compared to using alternative water sources. [ABSTRACT FROM AUTHOR]

Unplanned, high-density settlements in low-middle income countries often lack functional wastewater management systems. Nature-based solutions, such as constructed wetlands, are an option for the treatment of greywater, provided they are used by and useful to the community. We explored the effectiveness of iterative design for two pilot constructed wetlands in an informal settlement in Johannesburg, South Africa. Using ergonomics and human factors (E/HF) design approaches, this study evaluated the usability and postural risks associated with interactions with the constructed wetlands to motivate (and evaluate) design changes to increase use and reduce the risk of musculoskeletal pain. An elevated work area reduced musculoskeletal risks and a larger work area allowed more users at one time. The raised work areas provided other benefits such as stormwater and sewerage protection. The value of E/HF as part of a broader transdisciplinary team was demonstrated by embedding the design in the activities of the community. [ABSTRACT FROM AUTHOR]

Constructed wetlands (CWs) have great potential as low-cost natural wastewater treatment in developing countries. The present study appraises the performance of the vertical flow constructed wetland for domestic wastewater treatment. More specifically, the potential of Canna Indica in the removal of carbon, nitrogen, and phosphorus (CNP) from wastewater under tropical conditions. CW cell was fabricated with a vegetative layer of Canna Indica and tested with domestic wastewater. Based on the test results, Canna Indica shows a high Removal Efficiency (RE) of Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD5) on the order of 87% and 91%, respectively. Similarly, nutrients removal efficiency for total nitrogen (TN), total phosphorus (TP) was found to be 97% and 98%, respectively. The investigation also revealed that there is considerable removal of sulfates with efficiency equal to 78.4%. Overall, the Canna Indica based CWs were found to be suitable for wastewater treatment in the tropical regions, provided a viable medium for treating the wastewater in peri-urban and rural areas of developing countries. This study investigates the performance of Canna indica based vertical flow wetlands for greywater treatment. The study investigates the results at different hydraulic retention times and loading rates. There are no much studies reporting the performance of this variety of plant species under a tropical humid climate. The results from the study can encourage adoption of this plant variety, indigenous to this part of the country, for wastewater treatment It could emphasize the importance of familiarity with constructed wetlands to comprehend the RE of various climatic zones. It is possible to highlight the Canna-based CW's efficiency in removing organics and nutrients from domestic wastewater. The possibility for field-scale Canna-based CW to remove pollution in tropical climates was investigated, and Decentralization of wastewater treatment at the household level to apply CWs that will improve wastewater quality. [ABSTRACT FROM AUTHOR]

The efficacy of the well-known phytoremediation plant pistia (Pistia stratiotes), also called water lettuce or water cabbage, in treating sewage (greywater) was tested by its use as the main bioagent in the recently developed and patented 'sheet flow root level' (SHEFROL®) bioreactor. In contrast to previously reported systems, based on constructed wetland or stabilisation pond technologies, in which pistia needed wastewater hydraulic retention times (HRTs) of 24 h or more in enabling significant treatment of greywater, it achieved similar results in SHEFROL® several times more quickly, at the HRTs of only 4–6 h. Given that HRT directly influences reactor size, hence the system cost, the faster rate of treatment gives SHEFROL® a major economic advantage. In other ways, also, SHEFROL® appeared ideal for the use of pistia because of the reactor's ease of operation, robustness, very low requirement of energy or materials, and negligible ecological footprint. [ABSTRACT FROM AUTHOR]

This study considered the experimental parameters (zinc chloride, impregnation ratio and activation times) for nutrients removals (nitrate and phosphate) in synthetic greywater using activated carbon from banana trunk via Taguchi and response surface methodology (RSM). Lastly, the best optimization method was selected to optimize the experimental parameters for nutrient removal in synthetic greywater. For Taguchi method, the most influential experimental parameter was zinc chloride (ZnCl2), followed by impregnation ratio and activation time for both nitrate and phosphate removals. ANOVA results in Taguchi method found that ZnCl2, impregnation ratio, and activation time were significantly associated with phosphate removal. Only ZnCl2 and impregnation ratio were significantly associated with nitrate removal. Response Surface Methodology (RSM) adopting Box–Behnken Design findings indicated that ZnCl2 and impregnation time were the significant experimental parameters for nitrate removal. While, ZnCl2, impregnation ratio and activation time were significantly associated with phosphate removal in synthetic greywater. Three-dimensional surface plots illustrated that the nutrients removals (nitrate and phosphate) increase with the increasing of experimental parameters (ZnCl2, activation time, and impregnation ratio). The RSM method via Box–Behnken Design was chosen as it considered possible linear and non-linear combination interactions between two or more parameters with low errors. [ABSTRACT FROM AUTHOR]

Long-term savings can be achieved by small household improvements to deal with the increasing energy costs that are important to all of us. Hot shower greywater is discharged to the environment with a significant amount of thermal energy. In this study, unlike the studies in the field, the recoverability potential of the shower greywater thermal energy was experimentally studied and compared by the horizontal and vertical connection of the helical coil and brazed plate heat exchangers to a unit shower cabin. The shower water heating energy consumption of thermosiphon can be reduced by approximately 16.13% and 24.69% by mounting the helical coil heat exchanger horizontally and vertically. The saving rates reach 20.62% and 27.34% for brazed plate heat exchanger, too. It could be assessed that annual energy saving can be a minimum of 247.1 kWh and a maximum of 418.7 kWh for an average family of four people. The economic size of the saving was determined between $25.2 to $42.7, annually. The installation cost of a heat exchanger for a shower cabin is $87 and it was determined that the payback period could be 2 years. The reduction of carbon dioxide emission by the possible saving of energy is an estimated minimum of 203.85 kg/year. The study aims to contribute to the creation of literature for academic studies and design processes, as well as awareness for practitioners and investors. [ABSTRACT FROM AUTHOR]

A selective approach for multiple wastewater recovery is nowadays desirable and technologically feasible, to provide water at specific quality standards for each reuse objective. This "fit-for-purpose" approach to water reuse could both save water and would reduce production cost and energy demand by eliminating unnecessary treatment and long-range conveyance, as it typically aims at local reuses. The appropriate choice of technologies for such approaches is perhaps the most critical planning and design decision when evaluating systems for implementation or refurbishing. This article examines wastewater reuse goals (direct potable use, indirect potable use, non-potable uses and industrial uses) and related requirements as relevant case studies, and issues that may arise during implementation. It then proposes an overview of current conventional and advanced technologies and their possible combination to meet foreseen uses under a multiple barrier treatment (MBT) approach, which implies a sequence of complementary processes at an increasing level of protection for both conventional and emerging pollutants according to reuse goals. [ABSTRACT FROM AUTHOR]

This paper describes the development and application of a simulation tool to assess the impact of water-efficient appliances and greywater recycling strategies on the domestic water consumption and wastewater generation profiles. Two time-series datasets of domestic water consumption in UK households – each consisting of more than 20,000 observations – were used to deduce water use appliance usage patterns as a function of water consumption per use for each water-use appliance and household characteristic (e.g. occupancy). The deduced trends were then used to develop a simulation tool that can generate water consumption and wastewater generation profiles reflecting user input for water use appliances and household characteristics. The inbuilt flexibility in the tool allows investigation of each water use appliance both individually and collectively, and facilitates informed decision-making for devising targeted retrofitting programmes. This research has application for water service provision and policy making globally, with potential impact on both water supply and wastewater management. [ABSTRACT FROM AUTHOR]

This study presents a data-driven system analysis approach intended to improve greywater reuse at the household/community level using a case study of ¨Granular Activated Carbon-Membrane Integrated-Multigrade Effluent¨(GAC-MI-ME) treatment system. It consists of a matrix of advanced filtration units and provides multi-grade water reuse options. Using experimental data with varying greywater strengths, artificial neural networks were applied to develop effluent prediction models for water quality parameters including turbidity, total dissolved solids, five-day biochemical oxidation demand, oxidation redox potential and pH. The results show that the GAC-MI-ME can improve water quality with terminal removal efficiency of 99% and above for turbidity and BOD. At the same time, the model simulations can effectively predict effluent quality, which can be applied as decision-making tools in selecting and the treatment trains of GAC-MI-ME. The concept may help broaden the greywater reuse by ensuring it meets the requirements of diverse water reuse regulations. [ABSTRACT FROM AUTHOR]

There is limited information on the optimal processes to remove heavy metals in greywater. A Response Surface Methodology (RSM) via the Box–Behnken Design (BBD) approach was applied in this study to investigate and optimise the process variables of activation time (1.5–2.5 h), impregnation ratio (0.25–0.75) and zinc chloride (ZnCl2) percentage (20–60%) for the removal of heavy metal ions (Cd, Cu, Pb and Ni) associated with greywater treatment. The quadratic model was chosen to describe the effects of the process variables (activation time, impregnation ratio, ZnCl2 percentage) on predicting the responses (heavy metal ions removal) with low p-values (<.0001), high-adjusted R2 and predicted R2 values. Second order polynomial equations, ANOVA and three-dimensional surface plots were developed to evaluate the effects of each independent process variable and determine the optimal condition of each factor for heavy metal ions removal. The optimal activation time for the activated carbon variables was 1.8 h, with 56% ZnCl2 and 0.60 impregnation ratio. This showed that the observed values for removing the heavy metal ions (Cu, Cd, Pb and Ni) were close to the predicted values. A RSM-based field test via the BBD approach, involving different types of greywater samples (bathtubs, showers, hand basins and laundry machines) showed that the percentages of heavy metal ions removal fit the experimental results. [ABSTRACT FROM AUTHOR]

The unrestricted discharge of domestic and industrial wastewaters along with agricultural runoff water into the environment as mixed-wastewater pose serious threat to freshwater resources in many countries. Mixed-wastewater pollution is a common phenomenon in the developing countries as the technologies to treat the individual waste streams at source are lacking due to high operational and maintenance costs. Therefore, the need to explore the potential of the suspended growth process which is a well-established process technology for biological wastewater treatment is the focus of this paper. Different wastewater constituents: representing domestic, pharmaceutical, textile, petroleum, and agricultural runoff were synthesized as a representative of mixed-wastewater and treated in two semi-continuous bioreactors (R1 & R2) operated at constant operating conditions, namely MLSS (mg/L): 4640-R1, 4440-R2, SRT: 21-d, HRT: 48–72 h, and uncontrolled pH. The system attained stable condition in day 97, with average COD, BOD and TSS reduction as 84.5%, 86.2%, and 72.2% for R1; and 85.1%, 87.9%, and 75.1% for R2, respectively. Phosphate removal on average was by 74.3% in R1 and 76.6% in R2, while average nitrification achieved in systems 1 and 2 were 56.8% and 54.7%, respectively. The biological treatment system has shown potential for improving the quality of mixed-wastewater to the state where reuse may be considered and tertiary treatment can be employed to polish the effluent quality. [ABSTRACT FROM AUTHOR]

Groundwater (GW) storage plays a critical role in the sustainable development of the water-energy-food nexus of a country. Intensive exploitation of GW for irrigation has led to severe water deficit in many parts of India. Severe droughts (meteorological drought) further increases the rate of GW depletion. In the last decade, India witnessed severe droughts during 2002, 2009, and 2012. However, the critical change in the rate of GW depletion in India after frequent severe droughts remains unidentified. Here, we have devised a methodology to detect the point of maximum fluctuation in Gravity Recovery and Climate Experiment (GRACE) based GW time series using change point analysis. The occurrence of 2009 severe drought has significantly affected the GW balance over the majority of India. Our study indicates the transition in the GW trend observed in South India from positive to negative post-2009 drought. In the southern states, Karnataka indicates a maximum GW depletion rate of 0.25 cm per month for a time period from 2009 to 2016. [ABSTRACT FROM AUTHOR]

One of the important alternative water sources for non-potable purposes is greywater, but needs to remove contaminants. The aim of this study was to investigate the performance of a horizontal series filter (HSF) consists of sand, zeolite (Z), pumice (P), and granular activated carbon (GAC) to analyse the chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total dissolved solids (TDS), turbidity, and pH in greywater samples from Fasa University Student Hostel, Iran. Recycling treatment was performed by passing the greywater through filters. After the last filter, treated greywater was returned into the main tank. The system was run at filtration rate of 2.94 m3 day−1. The analysis of the data from the filtration tests showed that GAC is the best adsorbent for removing COD, BOD5, and TDS from greywater, followed by zeolite. Whereas, pumice is more advisable to remove turbidity. However, due to the different mass of adsorbents in the filters, pumice showed a higher adsorption capacity than zeolite. Generally, the triple combination of GAC+Z + P represented the best performance in the reduction of COD, BOD5, TDS, turbidity up to 90.42%, 91.43%, 82.95%, and 90.27%, respectively. Therefore, the studied system can be implemented in public places to greywater treatment and reuse. [ABSTRACT FROM AUTHOR]

Direct potable reuse (DPR) can improve reliability of water supplies by generating drinking water from wastewater, but communities have consistently opposed DPR more than other forms of reuse. Using interview data regarding DPR projects in five inland communities, this study fills gaps in the literature with an analysis of factors influencing acceptance of DPR. While scholars have recommended public processes used to implement non-potable and indirect potable reuse projects, there is little-to-no documentation about whether and how they have been used to implement DPR projects. Further, previous research has focused on large coastal cities. Counter to previous recommendations, we found minimal public deliberation of reuse options and public education/outreach occurring post-project conception. Findings suggest that direct experience with water scarcity, community smallness, and governance strongly influence DPR acceptance. With few DPR facilities worldwide, this new knowledge is useful to water planners who are interested in the feasibility of DPR in inland areas. [ABSTRACT FROM AUTHOR]

Vermifiltration technology using Eudrilus Eugeniae could be an alternative low-cost option for the treatment of urban greywater, which is highly polluted with high concentrations of surfactants, sodium and cooking oil. In this study, the effects of these pollutants on performance of a vermifiltration system was tested over a period of 6 to 8 weeks by enriching raw greywater with various concentrations of anionic surfactants (0, 15, 45 and 135 mg/L), sodium (0, 1, 2 and 4 g/L) and refined palm cooking oil (0, 250 and 500 mg/L). The vermifilter system was made of gravel, sand and sawdust layers from the bottom to the top, on which 200 earthworms were added. The greywater used in this study was previously used for dishwashing and laundry by an urban poor household. The greywater quality was compared with the effluent to evaluate the system performance. BOD5, COD, TSS and E. coli removal efficiencies ranged from 93% to 98%, 68% to 93%, 88% to 96% and 1.4-3 ULog, respectively, which are within the range of efficiencies reported in the literature. High proportion of surfactants (95–99%) and oil (84–89%) were removed but sodium was not removed. Instead, an increase in sodium concentrations was observed in the filter over the experimental period. Statistical analysis shows that BOD5, COD, TSS and E. coli removal efficiencies were independent of surfactants, cooking oil and sodium concentrations (p <.05). Thus, short term or accidental exposure of the vermifilter to high concentrations of these three pollutants did not have significant effect on the system performance. [ABSTRACT FROM AUTHOR]

In constructed wetland (CW) ecology, plants play a vital role in wastewater treatment. The plants provide an adequate surface to various microorganisms, transfers oxygen and uptake nutrients to treat wastewater. This study deals with the treatment of greywater by using vertical flow constructed wetland system (VFCW). In the present study, two reactors were prepared for two different orientations in monoculture (S-1) and mixed culture (S-2) by using four types of macrophytes (Canna indica, Colocasia, Hymenocallis littoralis, and Phragmites australis). The reactors were operated in continuous mode for 90 days by maintaining the 10 mL/min flow rate and 1-day retention time. The mean removal efficiency of S-1 is 40.70, 33.69, 27.13, 48.17, 66.76, and 50.82% for ammonia, total kjeldahl nitrogen (TKN), phosphate, sulfate, turbidity, and chemical oxygen demand (COD), respectively. The mean removal efficiency of S-2 CW is 53.06, 34.54, 37.49, 48.64, 69.26, and 58.26% for ammonia, TKN, phosphate, sulfate, turbidity, and COD, respectively. ANOVA showed significant differences among both VFCWs in removal efficiency for all measured parameters. The performance of the two systems was compared with each other with the significance level of p = 0.05. The results indicated that the orientation of plant plays a major role in the removal of various physicochemical parameters. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the potential for potable water savings by modelling the hypothetical installation of a system that combines rainwater and greywater in a house. The system consists of using rainwater to wash clothes and then reusing the effluent to flush toilets. The potential for potable water savings and the tank capacity for rainwater storage were estimated using the computer programme Netuno. A financial analysis was performed. For a rainwater tank capacity equal to 5000 litres, it was possible to obtain 51.6% potable water savings. The payback period was estimated as five years and three months. The system combining rainwater and greywater is a good alternative to save potable water because there was a significant reduction in potable water consumption and low payback period. The high potable savings and low payback period found in this work may contribute to the acceptability of these technologies and practices. [ABSTRACT FROM AUTHOR]

Water quality parameters of Holy River Ganga was analyzed at two major sites, namely, Triveni Ghat (Rishikesh) and Har ki Pauri (Haridwar) situated at Uttarakhand (India) between March 2016 and February 2018 to find out the extent of pollution in the river by using water quality index (WQI). Values of most of the parameters, viz., turbidity (7.79 NTU), pH (7.24), total dissolved solids (217.46 mg/l), biochemical oxygen demand (2.10 mg/l) and total hardness (90.69 mg/l) were found higher in the rainy season. During the study, it was observed that as the holy River Ganga flows from Rishikesh to Haridwar, the values of certain parameters, such as pH (7.22), biochemical oxygen demand (2.58 mg/l), total dissolved solids (201.92 mg/l) and total hardness (107.13 mg/l) increase. Similarities and variations between the parameters were analyzed by a multivariate statistical method like principal component analysis (PCA), Pearson correlation coefficient, cluster analysis (CA), t-test, etc. Pearson correlation matrix of physicochemical parameters strongly correlates with each other indicating the inter-dependency of the variables. Seasonal similarity in summer and winter in dendrodram shows the impact of anthropogenic activity on the water quality of the Ganga River. The value of WQI indicates better water quality at Rishikesh (35.23) than that at Haridwar (47.34). The study concludes that water of the Ganga River at both sites can be used for domestic and agricultural purposes but precautions and extensive measures are necessary before consumption. [ABSTRACT FROM AUTHOR]

Household effluents are predominantly treated by wastewater treatment plants (WWTPs). Other treatment methods, which were examined in this study, are also used in the countryside. These treatment modes include (1) onsite toilet wastewater treatment system (OTWTS), (2) onsite wastewater treatment system (OWTS), (3) community wastewater treatment system (CWTS), and (4) onsite vault toilet (OVT). Household effluents consist of excrements and urine released from toilets as well as wastewater released from kitchens and bathrooms. In the present study, household effluents that were discharged from the residential areas having undergone similar treatment methodologies were compared using the umu test, an in vitro bioassay to assess genotoxicity potential. The different treatment methodologies were categorized based upon whether the two kinds of wastewater were mixed or not mixed and treated or not treated. Treated wastewater containing excrements and urine from the OTWTS exhibited the strongest genotoxicity potential compared to other effluents, whereas most of the kitchen and bathroom wastewater from OVT did not display genotoxicity. Data indicated that the genotoxicants in the effluents originated primarily from excrements and urine, and may increase an adverse environmental risk. [ABSTRACT FROM AUTHOR]

Floating treatment wetlands (FTWs) are an innovative product of ecological engineering that can play a promising role in wastewater treatment. It provides low-cost, eco-friendly, and sustainable solutions for the treatment of wastewater, particularly in regions with economic constraints. Generally, FTWs comprise rooted plants that grow on the surface of water with their roots extending down into the pelagic zone rather than being embedded into the sediments. This drooping structure helps develop (1) a hydraulic flow between the root network and the bottom of the treatment system and (2) a large biologically active surface area for the physical entrapment (filtration) of contaminants, as well as their biochemical transformation and degradation. Furthermore, the rooted network allows proliferation of microorganisms that form biofilms and enhance pollutant degradation while promoting plant growth. The augmentation of bacteria in FTWs has been proven to be the most effective approach for reclamation of wastewater. This article discusses the operational parameters of FTWs for maximal remediation of wastewater and highlights the importance of plant-bacteria partnerships in a typical FTW system for enhanced cleanup of wastewater. We propose that this technology is preferable over other methods that require high energy, costs, and area to install or operate machinery. [ABSTRACT FROM AUTHOR]

The current paper investigates the development of two ornamental plants, canna lily (Canna x generalis) and giant horsetail (Equisetum giganteum), at both bench and pilot scale. Combinations of gravel-filled mesocosm, planted and unplanted (control), irrigated with light greywater (GWL) or tap water (WT), were used. Both species were able to grow under the tested conditions with no indication of toxicity that could affect the development. Irrigation with GWL, resulted in higher evapotranspiration (2.2 mm–2.8 mm) in canna lily than giant horsetail (1.7 mm–2.3 mm) in mesocosm system. When the plants were mature and the season was more humid and warmer, canna lily and giant horsetail irrigated with GWL evapotranspirated 69.23% and 30.77%, respectively as compared to the unplanted GWL-irrigated-mesocosm. Principal components and cluster analysis identified similarity between evapotranspiration (ET) and the characteristics of the plants. Both species can thus be used in constructed wetlands taking into consideration elements such as the space available, level of water and solar incidence so as to allow the full development of the plants. The roots of giant horsetail require high water availability. Low solar incidence is indicated for giant horsetail, and the opposite for canna lily, if flowering is desired. [ABSTRACT FROM AUTHOR]

Application of pilot-scale slurry-type tubular photocatalytic reactor was tested for the decentralized treatment of actual grey water. The reactors were fabricated by reusing the locally available materials at low cost, operated in batch recycle mode with 25 L of grey water. The influence of operational parameters such as catalysts' concentration, initial slurry pH and addition of H2O2 on COD abatement were optimized. The results show that Ag-decorated TiO2 showed a two-fold increase in COD abatement than did pure TiO2. Better COD abatement was observed under acidic conditions, and addition of H2O2 significantly increases the rate of COD abatement. Within 2 h, 99% COD abatement was observed when the reactor was operated with optimum operational conditions. Silver ion lixiviate was also monitored during the experiment and is five times less than the permissible limits. The catalyst shows good stability even after five cycles without much loss in its photocatalytic activity. The results clearly reveal that pilot-scale slurry tubular solar photocatalytic reactors could be used as a cost-effective method to treat grey water and the resulting clean water could be reused for various non-potable purposes, thus conserving precious water resource. This study favours decentralized grey water treatment and possible scaling up of solar photocatalytic reactor using locally available materials for the potential reuse of treated water. [ABSTRACT FROM AUTHOR]

The house engages the city fabric, integrates the built and natural environments, and experiments with construction materials and methods specifically calibrated to the sub-tropical climate. The house thus represents one-seventh of the embodied energy of a typical South Florida house. Keywords: architecture; landscape; built EN architecture landscape built 148 150 3 03/13/21 20210301 NES 210301 What is the most sustainable house we can build?. [Extracted from the article]

Constructed wetlands systems demand preliminary and primary treatment to remove solids present in greywater (GW) to avoid or reduce clogging processes. The current paper aims to assess hydraulic and hydrological behavior in an improved constructed wetland system, which has a built-in anaerobic digestion chamber (AnC), GW is distributed to the evapotranspiration and treatment tank (CEvaT), combined with a subsurface horizontal flow constructed wetland (SSHF-CW). The results show that both the plants present in the units and the AnC improve hydraulic and volumetric efficiency, decrease short-circuiting and improve mixing conditions in the system. Moreover, the hydraulic conductivity measured on-site indicates that the presence of plants in the system and the flow distribution pattern provided by the AnC might reduce clogging in the SSHF-CW. It is observed that rainfall enables salt elimination, thus increasing evapotranspiration (ET), which promotes effluent reduction and enables the system to have zero discharge when reuse is unfeasible. [ABSTRACT FROM AUTHOR]

In recent years, much interest has been given to presence of micropollutants in municipal wastewater, some of which are suspected to be endocrine disruptors, toxic or carcinogenic. Much less attention has been paid to their presence in greywater. The present research studies the diurnal patterns of micropollutants in greywater and computes their daily loads. Monitoring was carried-out using auto-controlled sampling system, designed to overcome the erratic greywater generation. Two main generation periods were identified: morning (5:00-11:00) and evening-night (18:00-2:00), contributing about 20% and >50% of daily greywater discharge, respectively. Average specific daily greywater discharge was 57 L p−1d−1, which matches reported value for greywater generated by showers and washbasins in Israel. The most frequently detected micropollutants in this study were methylparben (preservative), galaxolide (fragrance) and oxybenzone (UV-filter), which are common ingredients in many personal care-products. Their daily loads were 2, 840, 1, 887 and 728 µg p−1d−1, respectively. [ABSTRACT FROM AUTHOR]

This study aims at improving greywater reuse potential. An advanced physical filtration system named as GAC-MI-ME was developed to attain multi-grade effluents for versatile reuse of greywater. It consists of a matrix of treatment trains including coarse filtration, microfiltration, activated carbon, ultrafiltration, ultraviolet, and reverse osmosis. A preliminary set of experiments were conducted to characterize the greywater originating from shower, washbasin, and laundry. The samples were subsequently treated through GAC-MI-ME system. It was observed that the activated carbon along with microfiltration and coarse filtration played vital roles as pre-filtration for ultrafiltration and reverse osmosis. The contaminant load distributions of GAC-MI-ME system were observed with an average of 90.4% turbidity and 53.2% of biochemical oxidation demand (BOD5) as the pre-filtration, whereas the effluents at ultrafiltration and reverse osmosis showed unrestricted water reuse possibilities. The GAC-MI-ME system can be envisioned as advancement to the conventionally applied greywater treatments. [ABSTRACT FROM AUTHOR]

Seasonal water insecurity is a growing concern in many countries. For some households, rainwater and greywater are important alternative water sources. This study examines household patterns and socio-economic predictors of using rainwater and greywater in urban Philippines, in rainy versus dry seasons. Results from a household survey (N = 396) and in-depth interviews (N = 18) suggest that rainwater and greywater use are widespread, particularly among households with more members, less financial resources, and less access to the public utility, in seasonal ways. Future research into the adoption and diffusion of these practices may inform policies that promote equitable water access year-round. [ABSTRACT FROM PUBLISHER]

Together with significant water saving, due to lower wastewater discharges, greywater reuse (GWR) may also increase the impacts of faecal matter and other gross solids (GS) on sewer systems (sedimentation, blocking). Modelling and assessments of these effects require detailed descriptions of individual domestic wastewater streams. A novel stochastic methodology to generate such streams was developed and validated. The generator was developed while considering dependencies between in-house water-use events, and their varying degree of elasticity. These generated streams served as input to a sewer model, where scenarios of GWR were simulated and their effects on GS transport were examined. Extensive GWR decreases GS movement mostly in upstream links. Nevertheless, transient high flows, characterising these links, may move stationary GS and prevent blockages. The developed generator can be adopted to other sewer-related studies. Intelligent implementation of the results can assist in introducing GWR, or other water saving measures to the urban sector. [ABSTRACT FROM AUTHOR]

Zero-discharge constructed wetland environments are more prone to the accumulation of pollutants. The relationship between filter media and microbial communities in this type of environment is still poorly known. We conducted bench-scale studies of different filter media (polyurethane foam, blast-furnace slag, and loofah) in these systems by simulating the batch operation with light greywater for 433 days. Physicochemical and microbiological analyses (scanning electron microscopy and polymerase chain reaction electrophoresis denaturing gradient gel) were used. In all systems, anoxic environments prevailed. These environments were crucial for methanogenesis and sulfidogenesis processes, which are primarily responsible for organic material conversion. The chemical oxygen demand/sulfate (COD/SO42−) ratio was the limiting factor in the competition of microorganisms involved in these processes. This condition, combined with the neutral-alkaline pH, also allowed Chloroflexi phylum bacteria to oxidize sulfide to sulfate and elemental sulfur in all studied media. The results showed strong evidence supporting that the microbial community formed in the present study is more related to operational/environmental conditions than to the different tested filter media. Thus, this demonstrates that the control of interactive effects between pH, redox potential, and the COD/SO42−ratio can prevent the accumulation and/or release of sulfide in anoxic environments. [ABSTRACT FROM PUBLISHER]

An alternative water resource such as graywater could be used for irrigation on green roofs during hot, dry summers, although it contains salt. In this study, the response to high-salt stress of a C3–CAM (Crassulacean acid metabolism) intermediate species,Sedum kamtschaticumFischer, was evaluated over a 2-month experiment in terms of evapotranspiration (ET) and chemical compounds in plant tissue in triplicate for both experiments. High ET (10–15 mm day−1) was observed under non-stressed conditions. On the day following the first saline irrigation, the peak ET at noon decreased as much as one-third of the maximum. After 9 days, ET remained below 3 mm day−1, corresponding mostly to evaporation from the wet soil surface. The balance of chemical component contents in leaves changed depending on the electrical conductivity of irrigation water electrical conductivity (ECi). The potassium to sodium (K+/Na+) ratio, which indicates levels of sodium toxic for plant growth, decreased with higher ECi, while it excluded sodium from roots. However, based on enhanced water use efficiency under higher ECiregardless of reduced carbon dioxide (CO2) assimilation under salinity stress, the plant’s method of photosynthesis shifted from C3 to CAM metabolism. These findings show thatS. kamtschaticumcould survive for more than 2 months under low or moderate salinity of irrigation water in hot conditions. [ABSTRACT FROM PUBLISHER]

Electrocoagulation process is a new and developing method that has been employed significantly to remove pollutants from wastewater. In this research the electrocoagulation process has been examined for the removal of chemical oxygen demand (COD), turbidity, hardness, and organic matter from greywater. An economical comparison has been implemented between electrocoagulation and coagulation processes near the mining areas. The results demonstrate that the electrode type and operation time have a significant impact on the removal of COD, turbidity, and hardness. The least operating cost to remove organic matters is ~US$ 0.04 m−3for the iron electrode. Since the least operating cost was US$ 0.09 m−3in coagulation process, economically, the electrocoagulation process in comparison with the coagulation process is a more effective process. [ABSTRACT FROM AUTHOR]

Having in mind the immense value of the Danube River and knowing that risk assessment of its pollution is one of the key elements for ecology and the health of people in its region, in this paper we emphasized the importance of risk assessment of ship-generated wastewater – particularly in the case of greywater discharges. Although, a number of methods for measuring and analysing different environmental risks have been developed, previous research shows that the failure mode and effect analysis (FMEA) method is applicable in solving environmental issues. Therefore, we conducted our research with the main purpose to develop a model of FMEA method application for assessing the risks of ship-generated greywater discharges based on estimated data for total quantity of greywater, the size of the exposed population to the pollution of greywater and the possibilities of this pollution detection. Risk analysis was performed on official data for nine ports on the Danube River on inland waterways of the Republic of Serbia. Based on the obtained results, we concluded that measures, recommendations and risk prevention strategies for ship-generated greywater discharges should go into two major directions: (1) decreasing the pollution caused by greywater discharges; (2) increasing the number of water quality monitoring stations. [ABSTRACT FROM PUBLISHER]

The aim of the work is to describe the state-of-the-art on the reuse of grey water at building level taking into account (i) the grey water characteristics and amounts produced, (ii) the recycling guidelines, (iii) the treatment systems and reuse technologies, also considering the removal of micro-pollutants as xenobiotic organic compounds, and (iv) an overview of case studies for developed countries. The mini-review highlights how the existing technologies allow the safe reuse of grey water. Attention must be given to the removal of micro-pollutants especially when the discharge takes place in surface water. With reference to 12 case studies of buildings which adopt non-conventional technologies with the aim to optimise energy consumptions, results showed how the use of non-conventional technologies for water is very limited. However, adopting an integrated approach to water-energy, it is possible to use more effectively the water for energy purposes as in the cases of cooling/heating systems. [ABSTRACT FROM AUTHOR]

Treatment of greywater by electrocoagulation using aluminum electrodes was studied. The effects of current-density, electrolysis-time, and inter-electrode-gap on turbidity-removal and electrical-energy consumption were investigated. Under the optimal conditions (J= 12.5 mA/cm2,t= 30 min, andl= 0.5 cm), pollutants removal were: CODtotal= 52.8%, CODsoluble= 31.4%, BODtotal= 32.8%, BODsoluble= 27.6%, SS = 64.6%, TN = 30.1%, and TP = 13.6%. The consumed electrical-energy recorded 4.1 kWh/m3with an operating cost 0.25 US $/m3. Artificial intelligence was developed to simulate the influence of variables on the turbidity-removal. A 3–6–1 neural network achievedR-values: 0.99 (training), 0.84 (validation) and 0.89 (testing). An adaptive neuro-fuzzy inference system indicated that current-density is the most influential input. [ABSTRACT FROM AUTHOR]

This study evaluated the performance of unsorted soil media in the slanted soil treatment system, in terms of removal efficiency in suspended solids (SS), chemical oxygen demand (COD), linear alkylbenzene sulphonate (LAS) andEscherichia coli, and lifetime until clogging occurs. Unsorted soil performed longer lifetime until clogging than sorted fine soil. Removal of SS, COD, and LAS also performed same or better level in unsorted soil than fine soil. As reaction coefficients of COD and LAS were described as a function of the hydraulic loading rate, we can design a slanted soil system according to the expected hydraulic loading rate and the targeted level of COD or LAS in effluent. Regarding bacteria removal, unsorted soil performed sufficient reduction ofE. colifor 5 weeks; however, the removal process occurred throughout all four chambers, while that of fine soil occurred in one to two chambers. [ABSTRACT FROM PUBLISHER]

The article presents a speech by the author delivered for the Ven Te Chow Memorial Lecture at the 15th World Water Congress of professional organization International Water Resources Association (IWRA) in Edinburgh, Scotland on May 2015. Topics of the speech include water localization and food security, effects of greywater on soil water-holding capacity, and renewable water resources for North African Arab countries.

In the last decades, the focus on waste and wastewater treatment systems has shifted towards increased recovery of energy and nutrients. Separation of urban food waste (FW) and domestic wastewaters using source control systems could aid this increase; however, their effect on overall sustainability is unknown. To obtain indicators for sustainability assessments, five urban systems for collection, transport, treatment and nutrient recovery from blackwater, greywater and FW were investigated using data from implementations in Sweden or northern Europe. The systems were evaluated against their potential for biogas production and nutrient recovery by the use of mass balances for organic material, nutrients and metals over the system components. The resulting indicators are presented in units suitable for use in future sustainability studies or life-cycle assessment of urban waste and wastewater systems. The indicators show that source control systems have the potential to increase biogas production by more than 70% compared with a conventional system and give a high recovery of phosphorus and nitrogen as biofertilizer. The total potential increase in gross energy equivalence for source control systems was 20–100%; the greatest increase shown is for vacuum-based systems. [ABSTRACT FROM AUTHOR]

To solve the unpleasant disposal of greywater in rural area and allow its collection for reuse in gardening, a slanted soil treatment system (SSTS) was designed and installed in two households. Granitic gravel of 1–9 mm size was used as the filter medium. The aim of this study was to design a SSTS and assess its suitability as a treatment system allowing greywater reuse in gardening. The efficiency of the SSTS was assessed based on organic matter and bacterial pollution removal. The developed SSTS allowed the collection of greywater from three main sources (shower, dishwashing and laundry) in rural area. The SSTS is efficient in removing at least 50% of suspended solids, chemical oxygen demand and biological oxygen demand. The study highlighted that, contrary to the common perception, greywater streams in rural area are heavily polluted with faecal indicators. The removal efficiency of faecal indicators was lower than 2 log units, and the bacteriological quality of the effluents is generally higher than the WHO reuse guidelines for restricted irrigation. Longer retention time is required to increase the efficiency. The possibility of reusing the treated greywater as irrigation water is discussed on the basis of various qualitative parameters. The SSTS is a promising greywater treatment system for small communities in the rural area in the Sahelian region. To increase the treatment efficiency, future research will focus on the characteristics of the SSTS, the grain size and the establishment of a pretreatment step. [ABSTRACT FROM PUBLISHER]

In this paper, results of a new sand filter design were presented. The drawer compacted sand filter (DCSF) is a modified design for a sand filter in which the sand layer is broken down into several layers, each of which is 10 cm high and placed in a movable drawer separated by a 10 cm space. A lab-scale DCSF was designed and operated for 330 days fed by synthetic grey water. The response of drawer sand filters to variable hydraulic and organic loading rates (HLR and OLR) in terms of biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), pH, electrical conductivity andEscherichia colireductions were evaluated. The HLR was studied by increasing from 72 to 142 L m−2 day−1and OLR was studied by increasing it from 23 to 30 g BOD5 m−2 day−1while keeping the HLR constant at 142 L m−2 day−1. Each loading regime was applied for 110 days. Results showed that DCSF was able to remove>90% of organic matter and total suspended solids for all doses. No significant difference was noticed in terms of overall filter efficiency between different loads for all parameters. Significant reduction in BOD5and COD (P<.05) was noticed after water was drained through the third drawer in all tested loads. The paper concludes that DCSF would be appropriate for use in dense urban areas as its footprint is small and is appropriate for a wide range of users because of its convenience and low maintenance requirements. [ABSTRACT FROM PUBLISHER]

This paper presents the findings of an integrated household water treatment and reuse system for agriculture in La Soukra, Tunisia. The researchers found that the system has an internal rate of return of 17% and a net present value range from USD 26,000 (at a 5% discount rate) to USD 11,000 (for a 10% discount rate). Benefits included more water for irrigation, reduced costs to service providers, increased agricultural production from greenhouses and expanded agricultural options. These results suggest that investments in rainwater harvesting and greywater treatment at the farm level can increase the financial feasibility of peri-urban farms, which are often faced with pressure from urban growth. The systems can also help build household resilience to broader environmental change by lowering the exposure of farmers to burdens associated with infrequent access to water and poor-quality soil. [ABSTRACT FROM AUTHOR]

The increasing demand for water and the decrease in global water resources require research into alternative solutions to preserve them. The present study deals with the optimization of a treatment process, i.e. an aerobic fluidized bed reactor and the modelling of the degradation that takes place within it. The methodology employed is based on the hydrodynamics of the treatment process linked to the biodegradation kinetics of greywater coming from a washing machine. The residence time distribution (RTD) approach is selected for the hydrodynamic study. Biodegradation kinetics are quantified by respirometry and dissolved organic carbon (DOC) analysis on several mass quantities of colonized particles. RTD determinations show that there are no dysfunctions in the fluidized bed. Its hydrodynamic behaviour is similar to the one of a continuous stirred-tank reactor. A first-order reaction is obtained from the DOC biodegradation study. A model describing the degradation that takes place into the reactor is proposed, and from a sensitive study, the influence of the operating conditions on DOC biodegradation is defined. The theoretical results calculated from the first-order equation C(t) = 0.593 × C0 × e-kt are compared with the experimental results and validated by a Student test. The value of the kinetic constant k is 0.011 h-1 in the presence of a biomass carrier. The results highlight that it is possible to design a reactor in order to obtain a carbon content lower than 15 mgCL-1 when the characteristics of raw greywater are known. [ABSTRACT FROM PUBLISHER]

With a growing world population, the lack of reliable water sources is becoming an increasing problem. Reusing greywater could alleviate this problem. When reusing greywater for crop irrigation it is paramount to ensure the removal of pathogenic organisms. This study compared the pathogen removal efficiency of pine bark and activated charcoal filters with that of conventional sand filters at three organic loading rates. The removal efficiency ofEscherichia coliO157:H7 decreased drastically when the organic loading rate increased fivefold in the charcoal and sand filters, but increased by 2log10in the bark filters. The reduction in the virus model organism coliphage ΦX174 remained unchanged with increasing organic loading in the charcoal and sand filters, but increased by 2log10in the bark filters. Thus, bark was demonstrated to be the most promising material for greywater treatment in terms of pathogen removal. [ABSTRACT FROM PUBLISHER]

This paper presents a proposed centralised greywater reuse (CGR) system for Daxing New City, Beijing. This system would use separate greywater and blackwater discharge pipes in residences and public buildings. Greywater would be treated in a centralised plant and reused for public purposes. Water supply–demand balance analysis showed that this system would conserve 28.5% of freshwater resources. A centralised wastewater reuse system that would conserve the same water resources and serve the same consumers was developed for comparison. The greywater reuse system would cost 1.2% more than the reference system, but would decrease the pollution load by 10% and improve the water-quality compliance of the Xinfeng River (total phosphorous: 24–42%, total nitrogen: 0–7%). The proposed CGR system exhibited acceptable water conservation, environmental impact, and construction and operation costs, and would thus be suitable in urbanising areas that face water shortages and aqueous environmental deterioration. [ABSTRACT FROM PUBLISHER]

This simulation study, based on experimental and literature data, evaluates the influence of onsite greywater reuse on domestic wastewater quality and quantity. For this, three scenarios were studied: no reuse; reuse for toilet flushing; reuse for toilet flushing and garden irrigation. Light greywater reuse reduced the daily household wastewater flows by 25–40%. These reductions mainly occurred during the morning and evening peak wastewater generation. Although daily loads of all pollutants decreased, their concentrations in the discharged wastewater increased owing to exclusion of potable water from the wastewater and replacing it by treated light greywater. The proportional concentration increase of most pollutants was lower than the decrease in wastewater discharge, due to degradation during treatment. The highest concentration increase occurred during the morning peak, coinciding with the highest flow reduction. This study is a first step towards quantification of the effects of onsite greywater reuse on sewers and wastewater treatment plants. [ABSTRACT FROM PUBLISHER]

This study investigates the potential benefits of new technologies, modern appliances, and innovative techniques that help to improve the performance of the urban water cycle. Urbanisation is a major source of additional pressures (both qualitative and quantitative) on the environment. For example abstractions to cover the increased demands for water supply or alterations of the topographic and geomorphologic properties of the land cover result in considerable changes to the dynamics of the hydrosystem (change of average and maximum values of flows). Sustainable, water-aware technologies, like SUstainable Drainage Systems (SUDS) and rainwater harvesting schemes, can be implemented to reduce these adverse effects. These technologies introduce interactions between the components of the urban water cycle. Rainwater harvesting for example, apart from the potable water demand reduction, may have a significant influence on the generated runoff. Consequently, an integrated modelling of the urban water cycle is necessary for the simulation of the water-aware technologies and the identification of their combined benefits. In this study, two hypothetical developments implement rainwater harvesting schemes and SUDS and are simulated using the Urban Water Optioneering Tool (UWOT), which is capable of using rainfall time series of arbitrary time steps. The two hypothetical developments were studied to investigate the contribution of the water-aware technologies to the minimisation of the environmental pressures. Significantly different urban density was assigned to these developments to highlight the influence of urban density on the efficiency and reliability of the water-aware technologies. The results indicate that: (a) water-saving schemes like rainwater harvesting and greywater treatment can reduce significantly the pressures of new developments (e.g., reduction of potable water demand by 27%); (b) the reliability of the water-aware technologies decreases with urban density; and (c) if localised rainwater harvesting is implemented then the efficiency of the water appliances influences considerably the generated runoff. [ABSTRACT FROM AUTHOR]

Effluent and influent of a constructed wetland treating separately collected greywater were subjected to liquid/liquid extraction with dichloromethane as well as to solid phase extraction. Extracts were analysed by gas chromatography/mass spectrometry. More than 80 organics were tentatively identified or roughly characterised in the raw greywater by their mass spectra. A lower number (26) of organic compounds was tentatively identified in the constructed wetland's effluent. Major compounds found in at least one extract of the effluent were an alkane, a squalene isomer, hexadecanoic acid, two not exactly identified phthalates, tris-chloropropyl phosphate, an acephylline derivative and an unidentified nitrogenous heterocycle. The persistent flame retardant tris-chloropropyl phosphate and a couple of phthalates found in the biologically treated greywater are of concern when biologically treated greywater will be reused for high quality demand. Most of the trace organics found in the greywater samples were related to household chemicals, personal care products and foodstuffs. [ABSTRACT FROM AUTHOR]