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•Nature-based solutions (NBS) are a viable option for greywater (GW) treatment.•Review of case studies provided numerical thresholds for hydraulic design of NBS.•Life cycle assessment ...studies demonstrated the benefits of NBS for GW treatment.
Recognizing greywater as a relevant secondary source of water and nutrients represents an important chance for the sustainable management of water resource. In the last two decades, many studies analysed the environmental, economic, and energetic benefits of the reuse of greywater treated by nature-based solutions (NBS). This work reviews existing case studies of traditional constructed wetlands and new integrated technologies (e.g., green roofs and green walls) for greywater treatment and reuse, with a specific focus on their treatment performance as a function of hydraulic operating parameters. The aim of this work is to understand if the application of NBS can represent a valid alternative to conventional treatment technologies, providing quantitative indications for their design. Specifically, indications concerning threshold values of hydraulic design parameters to guarantee high removal performance are suggested. Finally, the existing literature on life cycle analysis of NBS for greywater treatment has been examined, confirming the provided environmental benefits.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Greywater reclamation has been well recognized as an alternative water resource for non-potable or potable use. To meet greywater reuse standards, various membrane-based techniques have been widely ...adopted to treat greywater for producing water with superior quality. This paper aims to present a comprehensive review on membrane-based techniques in greywater treatment, including direct pressure-driven and osmotic-driven membrane processes, hybrid membrane processes (such as membrane bioreactors and integrating membrane separation with other processes), and resource recovery oriented membrane-based processes. Membrane performance and treatment efficiency in the reported membrane-based greywater treatment systems are evaluated and membrane fouling mechanisms and control strategies are illustrated. The advantages, limitations, and influencing factors on membrane-based greywater treatment processes are highlighted. Towards long-term sustainability of greywater reclamation, the challenges and prospects of membrane-based greywater treatment are discussed.
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•Membrane-based greywater reclamation processes are reviewed.•Treated greywater by membrane processes can meet water reuse guidelines.•Hybrid membrane systems can enhance greywater treatment efficiency.•Optimization of membrane processes in greywater treatment is needed.•Life cycle assessment of membrane-based greywater treatment is suggested.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Organic media (date-seeds, SCG and coco-coir) achieved maximum removal of organics.•Phosphate was best removed by bone, 40% higher than SCG, the next best material.•Zeolite provided markedly faster ...and higher removal of ammonium than other media.•Perlite was not a good option for integrated greywater treatment application.•SCG kinetics for organic removal were much more rapid than other media.
Greywater recycling provides a means to address rising water demand with reduced environmental impact due to its abundance and lightly polluted nature. While many studies have examined high-tech treatment systems, these often require operator expertise and energy/chemical inputs that are not sustainable for a decentralised treatment process. Nature based systems such as green walls are emerging as alternatives. An effective plant support media is crucial to this treatment system and must be carefully chosen. This study compared the removal and kinetic performance of eight support media for nutrients and organic pollutants from synthetic greywater. The media were a mixture of organic and mineral materials, including waste-derived materials, and included: coco coir, spent coffee grounds (SCG), date seeds, SCG biochar, cattle bones, plastic carrier media, zeolite, and perlite. The best total organic carbon (TOC) removal was achieved by SCG biochar (50.7 %) and chemical oxygen demand removal (50.9 %) by zeolite. However, when accounting for leaching, which was significant in some organic media but expected to decrease with time, most organic media (SCG, date seeds, coco coir and bone) achieved around 80 % TOC removal. Of these materials SCG provided the most rapid removal. TOC and COD kinetics were best fitted by the pseudo-first-order model across all media except COD for SCG. The diffusion model plot indicates some diffusion-controlled process where sorbate concentration affects adsorption. COD elimination by SCG followed pseudo second order kinetics, suggesting chemisorption-dominated phenomena. The highest removal of phosphorus in greywater, after accounting for leaching, was achieved with cattle bone (88 ± 3.2 %), followed by SCG (55 ± 4.6 %). However, bone also had the highest phosphate leaching. Zeolite was the most effective in removing NH4+, achieving 82 ± 3.7 % removal. The dynamics of phosphate removal followed a pseudo-first order model for most media. Ammonia kinetics were best fitted by intra- particle diffusion and pseudo second order models. In summary, different media targeted different pollutants and a synergistic blend of these media holds the potential for efficient pollutant removal from greywater through nature-based processes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Linear alkylbenzene sulfonates (LAS) in greywater (GW) will simulate antibiotic resistance genes (ARGs) production in the biofilm-based system. Our study emphasizes the dissolved oxygen ...(DO)-dependent ARGs accumulation and microbial niches succession in an oxygen-based membrane biofilm reactor (O2-MBfR) treating GW, as well as revealing the key roles of EPS. Changing DO concentrations led to significant differences in ARGs production, EPS secretion and microbial communities, as well as the organics and nitrogen removal efficiency. Increasing DO concentration from 0.2 to 0.4 mg/L led to improved organics (> 90%) and nitrogen removal, as well as less EPS (especially for proteins and carbohydrates) and ARGs accumulation (e.g., intI-1, korB and sul-2) in the biofilm; the high-DO-concentration accumulated microbial niches, including Flavobacteriaceae and Cyanobacteria that revealed by LEfSe analysis, contributed to both nitrogen reduction and organics biodegradation. While, the inefficient electron acceptor at low DO conditions (0.2 mg/L) reduced the organics and nitrogen removal efficiency, as well as the improved accumulation of EPS in biofilm; high EPS enabled the capture of residual LAS from the liquid phase, which stimulated the production of ARGs by the distinct microbial community compositions. These findings suggested the DO-based ARGs reduction regulation strategy in the O2-MBfR treating GW.
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•DO induce the dynamics of performance, EPS, ARGs and microbial niches in the biofilm.•Higher DO led to higher aerobic bacteria and Cyanobacteria, and lower EPS and ARGs accumulation.•Lower DO led to higher EPS, niches of Cloacamonales and Leptospirales, and residual LAS.•High EPS alleviate LAS toxicity to microorganisms that allowing the stable performance.•High EPS captured more LAS and stimulate the secretion and accumulation of ARGs in biofilm.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Vertical greening systems (VGS) are implemented in the building envelope to address challenges such as the urban heat island effect, energy reduction, air purification, support of biodiversity and ...recently greywater treatment (wastewater without urine and faeces) for reuse purposes. In this context, providing and using treated wastewater is a crucial point, as generally VGS are irrigated with tap water and thereby increase urban water depletion and pollution. In this study, we evaluate the multifunctionality of a pot-based VGS irrigated with untreated greywater and capable, as well, of acting as a greywater treatment system. The full-scale experimental system uses a low-tech irrigation technique and was investigated for different irrigation water volumes to identify the needed water demand to maximize local cooling by evapotranspiration and suitable plants for the different water conditions and water types. Plant development and greywater treatment capabilities were monitored from April 2020 until September 2021. Based on the highest irrigation volume, a local air temperature reduction of up to 3.4 °C was measured. The removal efficiencies for treating greywater were COD 80 %, TOC 74 %, TNb 70 %, NH4-N 81 % and Turbidity 79 %, respectively, and showed a decrease in the second year of operation. Therefore, the results support the need to develop more robust systems, since up to now mainly short-term experiments have been reported in literature.
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•The substitution of tap water with greywater for irrigation purposes is a valid option.•The function of VGS to cool the local environment is directly related to the amount of irrigation water.•Suitable plants for dry, moist and wet conditions are identified.•The use of greywater for irrigation over two growing periods showed no quantifiable negative effects on the plant development.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Efficient removal of pharmaceuticals from greywater is crucial to enable its application for non-potable use. TiO2 photocatalysis is a promising environmentally friendly way of streamlining their ...complete degradation. However, dispersed TiO2 nanopowders are unsuitable for greywater treatment procedures because they require separation and may aggregate, thereby losing photocatalytic activity. Thus, TiO2 nanopowders (anatase 5 and 100 nm, AEROXIDE® P 25) were immobilized into layers by quantitative electrophoretic deposition. The layer ability to degrade the commonly used antibiotics ampicillin and sulfathiazole in deionized water was monitored using HPLC-PDA analysis and compared with that of the respective nanopowders. All layers attained total conversion of the initial antibiotics (limit of detection 50–100 μg L−1) with the highest degradation rate constant corresponding to 66 × 10−4 min−1 for AEROXIDE® P25 layer. To evaluate the efficiency of the prepared layers under more realistic conditions, collected greywater was treated in a membrane bioreactor, spiked with an equimolar antibiotic mixture, and subjected to photocatalysis. The overall reaction rate constants were calculated as 54, 15 and 75 × 10−4 min−1 for 5 and 100 nm anatase and AEROXIDE® P25 layers, respectively; the best-performing layer achieved complete removal and 68 % total mineralization of the antibiotic mixture in greywater within 7 and 24 h, respectively. For this layer, the developed regeneration method recovered min. 94 % of the original photocatalytic activity, enabling its reusability. These results suggest that our presented deposition method provides layers capable of degrading antibiotic mixtures in greywater effectively and is suitable for upscaling due to its low cost and simplicity.
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•All Q-EPD layers achieved sufficient antibiotic removal compared to nanopowders.•The best-performing P25 layer attained high level of degradation and mineralization.•Greywater and multiple antibiotic presence had no significant effects on conversion.•Furnace treatment was efficient for layer regeneration enabling their reusability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Greywater is being increasingly used as an alternative water source to reduce potable water demand and to alleviate pressure on sewerage systems. This paper presents the development of a low energy ...and low maintenance greywater treatment technology: a living wall system, employing ornamental plants (including vines) grown in a sand filter on a side of a building to treat shower, bath, and washing basin wastewaters. The system can, at the same time, provide critical amenity and micro-climate benefits to our cities. A large scale column study was conducted in Melbourne, Australia, to investigate the following design and operational factors of the proposed system: plant species, saturated zone design, rest period, hydraulic loading rate and pollutant inflow concentration. The results indicate that the use of ornamental species (e.g. Canna lilies, Lonicera japonica, ornamental grape vine) can contribute to pollutant removal. Vegetation selection was found to be particularly important for nutrient removal. While a wider range of tested plant species was effective for nitrogen removal (>80%), phosphorus removal was more variable (−13% to 99%) over the study period, with only a few tested plants being effective - Carex appressa and Canna lilies were the best performers. It was also found that phosphorus removal can be compromised over the longer term as a result of leaching. Excellent suspended solids and organics removal efficiencies can be generally achieved in these systems (>80% for TSS and >90% for BOD) with plants having a relatively small impact. Columns had an acceptable infiltration capacity after one year of operation. When planted with effective species (e.g. Carex appressa and Canna lilies), it is expected that performance will not be significantly affected by longer rest periods and higher pollutant concentrations in the early years of system operation. The results of this study, thus, demonstrate that innovative and aesthetically pleasing living walls can be designed for treatment of greywater at the household scale.
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•The hydraulic and pollutant removal performance of an innovative urban greywater treatment system are examined.•>80% and >90% removal efficiencies can be achieved for TSS and BOD respectively.•Nitrogen and phosphorus removal varied depending on plant type.•Use of ornamental flowers and climbers can contribute to system functioning.•Selected designs showed resilience against variations in operating conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Comparative LCA is applied for decentralized greywater treatment systems.•Community scale greywater treatment with water reuse performs best.•Environmental benefits of greywater reuse are ...significant.•Amount of reused water and electricity technology shares affect scenario preference.
Decentralized source-separated wastewater treatment systems offer an attractive alternative to conventional centralized wastewater treatment systems in various regions, yet few system analyses specifically address decentralized greywater treatment over different scales. Here we present a comparative life cycle assessment (LCA) and focus on global warming potential (GWP), eutrophication potential (EUP) and human health – carcinogenic potential (HHCP) of decentralized greywater management systems at different scales for a hypothetical community in a cold (winter) region. To provide a comparison between nature-based and engineered greywater treatment solutions, constructed wetlands (CW) and membrane bioreactors (MBR), respectively, were investigated at three different scales; community (3500 person equivalent PE), neighborhood (350 PE) and household (a single household up to 5 PE). Conventional centralized wastewater treatment was also included as a business-as-usual (BAU) scenario. In the MBR scenarios, greywater reuse was also considered for multiple non-potable applications due to its high-quality effluent and subsurface garden irrigation was considered for reuse in the CW scenarios. For scenarios with the same treatment technology, larger scales reduced GWP, EUP and HHCP up to 57 kg CO2-eq.PE−1.y−1, 0.2 kg N-eq.PE−1.y−1 and 5.3E-6 CTUh.PE−1.y−1, respectively, despite the need for more extensive wastewater networks. The CW scenarios at community and neighborhood scales outperformed the MBR and BAU scenarios for greywater treatment, while the community-scale MBR scenario may be environmentally preferable when large amount of greywater can be reused. The scale of decentralized systems, quantity of water reused and mix of electricity technologies all played important roles in determining GWP, EUP and HHCP values.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Micropollutant removal from effluent of conventional wastewater treatment has recently become one of the most discussed topics in the design and operation of wastewater treatment plants (WWTPs). This ...is due to the need to add a post-treatment step to the conventional processes to comply with stricter quality standards for effluents as outlined in the revised Urban Wastewater Treatment Directive (UWWTD). The adoption of on-site or decentralized greywater (GW) treatment in sustainable buildings using vertical-flow constructed wetlands (VFCWs) is a promising direction. It represents an interesting alternative for the removal of micropollutants at the source of pollution, such as personal care products (PCPs) and some pharmaceuticals which are mainly present in this wastewater fraction. Additionally, the treated greywater could be used in households' water services which do not require potable water quality, thus saving drinking water. In this context, this work compares the results of micropollutant removal from projects using VFCWs as a polishing step of WWTPs effluent, as a centralized solution, to the results from a decentralized GW treatment. The results show that VFCWs can remove the investigated micropollutants (Diclofenac and DEET) with an efficiency of >90 %, in both centralized and decentralized treatments. The admixture biochar from plant residues and from cellulose-toilet paper proved to be a promising substitute for the mineral zeolite when mixed with sand to remove PCPs from GW and, therefore, a circular economy concept can be applied to this technology.
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•On-site greywater treatment can save at least 30 % of potable water.•Vertical-flow constructed wetlands are sustainable option for greywater treatment.•Biochar produced in a circular way is suitable as supporting material in wetlands.•Personal care products can be removed by on-site greywater treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The increasing demand for fresh water has been a global concern for decades. Desalination and water transportation systems consume an ample amount of energy, which also adds to the environmental ...pollution. This has led to a constant look-out for more viable options to conserve freshwater resources without compromising the environmental quality. The building sectors are remarkably the largest consumers of fresh water in the world; thus, the reclamation and reuse of greywater for non-potable purposes helps to reduce a significant amount of water consumed within a building. This study critically reviews the environmental performance of building-integrated greywater treatment systems compared to the conventional treatment systems deployed. Life-Cycle Assessment (LCA) is the method used to identify the environmental impacts associated with both the systems during their entire life span. The greywater treatment techniques and the guidelines for its reuse are also investigated. The bibliographic analysis was systematic, and the resources for this study were chosen after three stages of quality assessment. The study found physical and biological treatment techniques to be beneficial as they produce excellent quality of treated greywater for reuse. The environmental assessment by various studies prefers the reuse of greywater over its disposal. Guidelines for the reuse of treated greywater have recently been proposed by various countries and building rating systems. This study aims to address the policymakers, governmental and environmental organizations, mainly situated in the water-stressed areas such as the Middle East and North Africa (MENA) region, to raise awareness and initiate greywater reuse techniques within residential and commercial building sectors.
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•Significant 50–80% of the household wastewater can be classified as greywater.•Biological treatment techniques are highly efficient compared to physical and chemical.•On-site greywater reuse is highly advantageous and can positively impact the environment.•Policymakers & governmental agencies of water scarcity regions should promote such systems.•Current building standards & codes underutilizing the benefit of those systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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