Greywater Research Articles

Performance of Agricultural Wastes as A Biofilter Media for Low-Cost Greywater Treatment Technology

Performance of Agricultural Wastes as A Biofilter Media for Low-Cost Greywater Treatment Technology

Nitrogen cycling and associated grey water footprint in croplands under different irrigation practices

Nitrogen cycling and associated grey water footprint in croplands under different irrigation practices

Performance of an integrated household greywater treatment system for water optimization and reuse

This study evaluated the efficiency of an on-site household greywater treatment system for indirect human reuse and for domestic lawn irrigation. This helps in the reduction in the disparity between water demand and supply that is facing the rapidly increasing global populace. Natural household greywater was settled and then conventionally filtered by using two types of non-woven geotextile media; thermally bonded and needle punched. A third woven cotton textile media was also experimented and all the non-woven geotextile media were tested in single and double layers and combined with the woven cotton textile layer. The different filter media configurations were tested for a period of one year operation (six runs) with two filtration rates of 15.00 and 25.00 m3/m2/day for each run. For all runs, the final treated effluent was disinfected using calcium hypochlorite prior to reuse. The double layer needle punched non-woven geotextile media together with the woven cotton textile media gave the best removal efficiencies; 96.34 ± 1.85% for turbidity 81.87 ± 6.43% for BOD5, 97.49 ± 1.68% for TSS, 75.35 ± 3.99% for CODt, 99.59% for E.coli. The soluble CODs removal efficiencies were negligible (below 3%) in the first four runs with non-woven geotextile media and increased to 28.05 ± 4.29% when the woven cotton textile media was added. In general, the system was found to save about 63% of the daily water consumption reflecting a net 22.50% reduction in the daily water billing costs for the whole household.

Use of native macrophyte Echinodorus subalatus for grey water treatment applying alternative bed substrate in constructed wetlands

ABSTRACT Two vertical flow constructed wetland (VFCW 1 and VFCW 2) with native macrophyte Echinodorus subalatus (Mart.) were operated. In VFCW 1, the substrates used were ceramic brick, washed sand, seashells (Anomalocardia brasiliana), and ceramic brick and sand in VFCW 2. The system was operated for 74 days, in batches, with cycles of 168 h, and fed with synthetic grey water. The presence of seashells in VFCW 1 was a differential factor (p < 0) for the removal of anionic surfactant (94.09 ± 7.77%), COD (88.43 ± 5.43%) and total phosphorus (45. 98 ± 9.86%) when compared to VFCW 2. The Langmuir isotherm was used to calculate the substrate adsorption capacity for total phosphorus, anionic surfactant, and COD. The results showed that adsorption on support materials was not the primary mechanism of pollutants removal. From 16S sequencing, it was observed that phylum Firmicutes was the most abundant (96.5%), followed by phylum Proteobacteria (3.5%). The results suggest that using seashells as an alternative substrate improved pollutant removal efficiency.

Greywater irrigation of pepper plants: Possible application and its impact on soil and plant growth

AbstractGreywater reuse may be considered a water source that can compensate for water scarcity. Reusing treated greywater on fields instead of disposing of it would be more environmentally friendly. The objective of this study was to investigate the physiological response of pepper plants to the application of both untreated and treated greywater. The greywater obtained from Al‐Huson University College was treated with zeolite filters before being used for plant irrigation in the experiments. The electrical conductivity (EC), total dissolved solids (TDSs) and chemical oxygen demand (COD) of greywater were all higher than those of tap water by 44%, 68% and 509%, respectively. The results demonstrated that plants irrigated with tap water and treated with greywater presented greater fruit and biological productivity than did those irrigated with untreated greywater. The use of treated greywater led to a notable 8.3% increase in overall chlorophyll levels. Irrigation of pepper plants with untreated greywater led to a 33% increase in electrolyte leakage. The plants irrigated with greywater presented the highest levels of proline and total soluble sugars. Compared with those in all the other water treatments, the plants irrigated with greywater presented significantly greater magnesium and salt concentrations. Typically, treated greywater has the most significant impact on agricultural productivity.

A novel framework reveals anthropogenic stressors of phosphorus polluted river-lake connection water system in Poyang lake basin of China

Poyang lake (PYL), as China's largest freshwater lake, has been suffering from increasing total phosphorus (TP) pollution associated with rapid basinal socio-economic development. However, anthropogenic phosphorus stressors were rarely examined in PYL basin due to its large-scale and complex river-lake connection water system, hampering phosphorus pollution control efforts. In this study, water pollution stress from multiple anthropogenic activities is quantitatively examined in PYL basin based on a newly developed framework coupling grey water footprint (GWF) analysis with the SPARROW model. Results show that the phosphorus source-sink process in PYL basin has been well simulated by SPARROW model quantifying an overall TP delivery rate of 0.39, with catchments closer to PYL showing higher delivery rate of phosphorus (up to over 0.8). The GWF analysis demonstrates that anthropogenic phosphorus sources have imposed much higher pollution stress on PYL than its inflowing rivers, with twelve catchments nearby PYL identified as critical source areas of TP contamination. Agricultural farming, livestock & poultry production, and urban household are recognized as the dominant anthropogenic stressors burdening water environment of PYL. Based on these, policy recommendations are provided for advancing control of the phosphorus pollution stressors. The methodology is effective in refined examination of water pollution sources, which is expected to be applied in other watersheds providing informative diagnosis of water issues especially in lakes.

Navigating the path: regulatory readiness and stakeholder insights in Indonesia's citywide inclusive sanitation landscape

Inadequate sanitation has catastrophic consequences for public health, standard of living, and productivity, as well as gender equality and social inclusion. Urban sanitation programmes yield suboptimal outcomes regarding long-term impact, effectiveness, sustainability, and fairness. To ensure that all urban dwellers in Low- to Middle-Income Countries (LMICs) have access to sanitation facilities that are properly maintained and safe, it is crucial to bring about a fundamental change in the urban sanitation sector through the implementation of Citywide Inclusive Sanitation (CWIS). This research analyses the sanitation regulatory framework and stakeholders' perspectives in Bandung City, Indonesia. The goal is to determine the possible obstacles and advantages of implementing a comprehensive CWIS (Citywide Inclusive Sanitation) system in Indonesia. The CWIS idea has been recognised at the national level in Indonesia. While existing legislation and policies partially govern and deal with CWIS components, there is no official programme establishment yet and limited implementation at the local level. Some challenges that have been identified include conflicting priorities in serving marginalised populations, a lack of political commitment and capacity to provide comprehensive services for all types of domestic wastewater (including grey water) and throughout the entire sanitation service chain (from containment to treatment and/or reuse and recovery), inadequate knowledge management and data transparency, a lack of incentives and penalties for local governments to meet sanitation standards, and limited motivation for meaningful and institutionalised private sector involvement. This study also delineates four crucial domains for efficiently fostering the deployment of CWIS in Indonesia.

Lepidium peruvianum as a Source of Compounds with Anticancer and Cosmetic Applications

Lepidium peruvianum—an edible herbaceous biennial plant distributed in the Andes—has been used for centuries as food and as a natural medicine in treating hormonal disorders, as an antidepressant, and as an anti-osteoporotic agent. The presented study aims to prove its beneficial cosmetic and chemopreventive properties by testing the antiradical, whitening, cytotoxic, and anticancer properties of differently colored phenotypes that were extracted using three solvents: methanol, water, and chloroform, with the help of the chemometric approach to provide evidence on the impact of single glucosinolanes (seven identified compounds in the HPLC-ESI-QTOF-MS/MS analysis) on the biological activity of the total extracts. The tested extracts exhibited moderate antiradical activity, with the methanolic extract from yellow and grey maca phenotypes scavenging 49.9 ± 8.96% and 48.8% ± 0.44% of DPPH radical solution at a concentration of 1 mg/mL, respectively. Grey maca was the most active tyrosinase inhibitor, with 72.86 ± 3.42% of the enzyme activity calculated for the water extract and 75.66 ± 6.21% for the chloroform extract. The studies in cells showed no cytotoxicity towards the human keratinocyte line HaCaT in all studied extracts and a marked inhibition of cell viability towards the G361 melanoma cell line, which the presence of pent-4-enylglucosinolate, glucotropaeolin, and glucoalyssin in the samples could have caused. Given all biological activity tests combined, the three mentioned compounds were shown to be the most significant positive contributors to the results obtained, and the grey maca water extract was found to be the best source of the former compound among the tested samples.

Enhancing Greywater Treatment: High-Efficiency Constructed Wetlands with Seashell and Ceramic Brick Substrates

Constructed wetland (CW) systems have been recognized as a sustainable technology for wastewater treatment that can be easily integrated into the local natural environment, offering both low cost and high efficiency. In this study, synthetic greywater was treated using a vertical subsurface flow CW operated in batch mode with 7-day cycles across two phases, operated in parallel: I, non-vegetated, and II, vegetated, with Echinodorus subalatus. The mixed filter bed was composed of seashells, ceramic brick fragments, and sand. No statistically significant differences (p &gt; 0.05) were observed between the non-vegetated and vegetated phases for most parameters. The removal efficiencies of organic matter, anionic surfactants, and total phosphorus in the non-vegetated versus vegetated phases were (91.0 ± 3.8)% versus (94.0 ± 1.1)%; (71.9 ± 14.1)% versus (60.0 ± 9.5)%; and (35.2 ± 4.6)% versus (40.2 ± 15.5)%, respectively. Phosphorus removal exceeded values reported in the literature for both phases, primarily due to the calcium present in the seashells, which increased the electrical conductivity and hardness of the effluent compared to the influent. The macrophyte exhibited leaf desiccation, possibly due to contact with greywater and its young age (30 days), which may have negatively impacted the system’s performance during the vegetated phase.

Optimizing greywater treatment in green walls: A comparative analysis of recycled substrate materials

The utilization of green walls for on-site greywater treatment in urban buildings has garnered significant attention in recent research, with substrates playing a vital role in treatment performance. The incorporation of recycled materials as substrates not only offers a cost-effective solution for greywater treatment, but also enhances sustainability by repurposing wastes. This study investigates the efficacy of three recycled substrates: alum sludge, garden compost, and a mixture of perlite-coconut fiber in three green wall systems for greywater treatment. Each substrate was allocated to a three-pot column. Comparative analysis revealed alum sludge (C3) and the coconut fiber-perlite mix (C1) achieving the highest chemical oxygen demand (COD) removal at 89.45 ± 2.92 % and 89.34 ± 2.47 %, respectively, with garden compost (C2) recording 67.98 ± 7.45 %. For total nitrogen (TN) removal, C2 achieved the lowest efficiency (49.27 ± 9.39 %), while C1 demonstrated 83.79 ± 10.45 %. Notably, C3 exhibited superior total phosphorus (TP) removal at 94.86 ± 1.87 %, compared to 52.07 ± 17.88 % for C1 and 24.90 ± 30.95 % for C2. Our findings demonstrate that substrate selection is crucial for optimizing both pollutant removal and plant health in green walls. The coconut fiber mix emerged as the most effective substrate, supporting robust plant growth and superior pollutant removal, particularly for nitrogen removal. In contrast, garden compost proved unsuitable, with minimal plant survival post-greywater introduction. Alum sludge showed significant promise, particularly for TP removal, reinforcing its effectiveness in green walls. These insights underscore the importance of substrate optimization in greywater treatment systems in urban environments.

Experimental study based on the usage of polymers for greywater treatment

Water scarcity presents a pressing challenge in Egypt, exacerbated by factors such as population growth, urbanization, and climate change impacts. With over 95% reliance on the Nile River for freshwater supply, Egypt's water resources are strained, particularly with a population exceeding 100 million. Egypt's arid climate intensifies water scarcity, necessitating sustainable management strategies. This study explored greywater treatment as a solution to alleviate water scarcity in Egypt, investigating its technical feasibility, economic viability, and environmental benefits. Greywater, derived from domestic activities, is an underutilized resource that can be reclaimed and treated for reuse, reducing demand for freshwater sources. Through greywater treatment systems, households and communities can recycle water, conserve resources, and mitigate pollution. The study investigated using polymers as a coagulant in greywater treatment, examining its efficacy in removing contaminants and improving water quality. Experimental trials were conducted to evaluate the performance of polymer addition in greywater treatment compared to conventional methods. Results demonstrate that polymer addition reduces turbidity, suspended solids, and organic pollutants in greywater. Poly aluminum chloride (PAC) polymer, in particular, exhibits strong coagulation capabilities, versatility across pH ranges, and high efficiency in contaminant removal. Additionally, PAC offers operational advantages such as low dosage requirements and reduced sludge production.

Use of Vertical Greenery Systems for the domestic scale treatment of greywaters for fit-for-purpose reuse. Applicability and future prospects.

Abstract Only less than 1% of the Earth’s water is fit for human activities. Domestic consumption accounts for roughly 20% of all uses of water, adding pressure to the increasing water scarcity stress. Water intakes of residential buildings for all everyday uses are constituted by a high-quality resource, which is either costly to produce or conspicuous in amounts to withdraw from natural sources. The present proposal aims to test the feasibility of the application of decentralized greywater treatment strategies, based on the use of vertical greenery systems integrated into residential buildings to assess both the optimal scale of application in residential settlements and a comparative analysis on reclaimed water resource savings. The aim is to promote the circular use of water resources by allowing for fit-for-purpose employment, thus reducing the overall intake due to the residential sector. The methodology hereby proposed has been developed using as a case study the most widespread residential typologies in the Southern Italian context, such as single detachment, row houses, low and medium-rise apartment buildings. The result is the proposition for each residential typology of a retrofitting strategy that employs the integration of a green infrastructure inside the residential spaces. Until now, the Mediterranean context has been characterized by limited use of strategies directed towards the efficient employment of water resources, since the mild climatic conditions have always provided for an adequate amount of freshwater. Therefore, limited studies have been carried out on the application of those strategies in Mediterranean landscapes. However, the rapid shift in precipitation patterns due to climate change has defined the need to quickly embrace new strategies, systems, and technical solutions for improving water use efficiency and promoting reuse.

Efficient and Sustainable Removal of Linear Alkylbenzene Sulfonate in a Membrane Biofilm: Oxygen Supply Dosage Impacts Mineralization Pathway

Linear alkylbenzene sulfonate (LAS) can be thoroughly mineralized within sufficient oxygen (O2), but which is energy intensive and may causes serious foaming problem. Although cometabolism can achieve efficient LAS removal within a wide range of O2 dosages, how O2 dosage systematically affects LAS metabolic pathway is still unclear. Here, membrane aerated biofilm reactor (MABR) enabled accurate O2 delivery and bulk dissolved oxygen (DO) control. MABR achieved efficient removal of LAS (> 96.4%), nitrate (> 97.8%) and total nitrogen (> 96.2%) at the three target DO conditions. At high DO condition (0.6 mg/L), LAS was efficiently removed by aerobic mineralization (predominant) coupled with aerobic denitrification biodegradation with the related functional enzymes. Pseudomonas, Flavobacterium, Hydrogenophaga, and Pseudoxanthomonas were dominant genus contributing to four possible LAS aerobic metabolic pathways. As O2 dosage reduced to only 29.7% of the demand for LAS mineralization, O2 facilitated LAS activation, benzene-ring cleavage and a portion of respiration. NO- 3-N respiration-induced anaerobic denitrification also contributed to ring-opening and organics mineralization. Desulfomicrobium and Desulfonema related two possible anaerobic metabolic pathways also contributed to LAS removal. The findings provide a promising strategy for achieving low-cost high LAS-containing greywater treatment.

Microplastic retention in green walls for nature-based and decentralized greywater treatment

In wastewater treatment, two issues have recently received increased attention: nature-based solutions for addressing urban water stress through decentralized treatment and re-use; and emerging pollutants such as microplastics (MPs). At the interface of these, this study investigated living green walls for greywater treatment and their potential for MP removal.A large, pilot-scale green wall was irrigated with greywater (a mix of water collected from laundry, dishwasher, bathroom sinks, and synthetic greywater), and effluent from planted and unplanted sections was compared. MPs >50 μm were analyzed using μRaman spectroscopy and supplementary fluorescence microscopy imaging. The green wall proved efficient for the reduction of chemical oxygen demand (COD) (around 80%), removal of total suspended solids (TSS) (around 90%) and MPs, especially for MPs of the non-polar, hydrophobic polymer type polystyrene and MPs sized 100–500 μm. MP removal was improved in the planted (50–60%) compared to the unplanted section (20%), especially for the size fraction 100–500 μm. Physical filtration by the green wall growing media (a mix of perlite with a grain size of 1–5 mm, and coconut fiber), which was further enhanced by plant roots decreasing the effective pore size, can be considered the most important removal mechanism. Charge-mediated adsorption cannot be expected as MPs and growing media mix were both negatively charged at the prevailing water pH (7–8). Fluorescence imaging for MP analysis, using a merged UV/blue light fluorograph, overestimated MP concentrations in greywater (hundreds of MPs per sample were identified by fluorescence imaging versus tens of MPs by μRaman spectroscopy) and would benefit from further improvement before it can be reliably applied as a cheaper and faster alternative methodology for MP analysis.

Comparative study of greywater treatment using activated carbon and woodchip biochar for surfactant and organic matter removal

Greywater (GW) treatment is recognized as a more efficient alternative to blackwater treatment, particularly for reuse applications, due to its lower pathogen content and higher concentrations of chemical oxygen demand (COD) and surfactants. In this study, the adsorption performance of woodchip biochar (BC) and activated carbon (AC) was compared for the removal of COD, anionic surfactants (ASU), and non-ionic surfactants (NISU) from GW. Response Surface Methodology (RSM) was employed to optimize the removal efficiency of both organic matter and surfactants. AC demonstrated higher adsorption capacities for COD and ASU, with KL = 0.007 L/mg and Qmax = 0.95 mg/g for COD, and KL = 1.4 × 104 L/mg and Qmax = 0.08 mg/g for ASU. In contrast, BC showed a significantly higher affinity for NISU, with KL = 8.4 × 103 L/mg and Qmax = 0.01 mg/g. Breakthrough curves and pseudo-first-order (PFO) kinetics provided insights into adsorption dynamics, with AC showing delayed breakthrough and greater longevity, while BC offered rapid adsorption and cost-effectiveness. The treated GW achieved substantial reductions in contaminant levels, with final COD and surfactant concentrations reduced to approximately 10 mg/L and 0.05 mg/L, respectively, meeting Italian and Australian regulatory standards. The study highlights the potential of woodchip BC as a cost-effective and sustainable alternative to AC, particularly for short-term adsorption applications, and offers valuable insights into the treatment of GW for reuse.

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.

Effects of hydrological variability on the sustainable use of water in a regional economy. An application to Tuscany

Existing input-output (IO) models have mainly focused on water demand. Some studies have incorporated water supply (availability), but do not take into account its natural variability, an essential element when performing a water stress analysis. The present study integrates the hydrological variability of water availability into a hydroeconomic IO model, considering its exogenous effects on water supply and its exogenous effects on water demand. Two endogenous effects are considered: i) changes in blue water requirements in the agricultural industry due to variations in precipitation and evapotranspiration, and ii) changes in grey water requirements in all discharging industries due to variations in runoff and groundwater recharge. By means of a T-years hydrological series and Monte Carlo simulations, the model allows estimating T values of the Extended Water Exploitation Index (EWEI), obtaining its empirical probability distribution and confronting it with scarcity thresholds. Additionally, the model includes a methodology to incorporate intra-annual variation, obtaining the critical month EWEI and defining a more transparent and endogenous scarcity threshold. Empirically tested for the Italian region of Tuscany considering a multivariate hydrological model for the generation of a 100-year hydrological series, our results allow a more in-depth analysis of water scarcity in the region.

Evaluating a vertical greening system mesocosm for kitchen greywater treatment: Comparison among vegetation species in water consumption, biomass growth and pollutants uptake and removal

The escalating climate imbalance, coupled with rising water demands in rapidly expanding urban areas, is forcing scientists and policymakers to seek alternative strategies for efficient water resource management. Nature Based Solutions (NBS) are gaining prominence due to their ability to provide multiple ecosystem services. However, the quantification of benefits and drawbacks mediated by different vegetation species remains inadequate. In this study, we investigated the performance of a pot-based vertical greening system (VGS) designed to integrate the functions of green facades with those of treatment wetlands. The VGS was vegetated with Mentha aquatica L. (hereafter Mentha), Oenanthe javanica (Blume) DC. (hereafter Oenanthe) and Lysimachia nummularia L. (hereafter Lysimachia), and their respective effects on water balance and mass removal of common greywater pollutants were compared. Results indicated that VGS lines vegetated with Oenanthe and Mentha exhibited comparable pollutant removals. Oenanthe showed a preference for greywater that had already undergone partial treatment, while Mentha was not affected by any pollutant load in water removal −48.1 % of total inflow– and in nutrients uptake in aboveground biomass −14.3 % N and 7 % P– due to sustained and robust growth, outperforming Oenanthe and Lysimachia. This has suggested the potential use of Oenathe in combination with Mentha for enhanced performances, particularly given Oenanthe's rapid growth in the early season and high biomass and nitrogen content following initial greywater treatment.

Anaerobic Fluidized Bed Membrane Bioreactor with Multichanneled Biocarrier for Carbon-Neutral, Decentralized Greywater Treatment

Anaerobic Fluidized Bed Membrane Bioreactor with Multichanneled Biocarrier for Carbon-Neutral, Decentralized Greywater Treatment

Food waste reduction and its environmental consequences: a quasi-experimental study in a campus canteen

BackgroundFood waste is the third-largest contributor to greenhouse gas emissions, which has severe environmental and economic effects. This study presents a two-level intervention to estimate the quantity and environmental consequences of food waste at a campus canteen, offering innovative solutions to reduce food waste and its environmental footprint.MethodologyThis study involved 300 students and consisted of three main stages: initial food waste assessment, environmental and economic impact evaluation, and qualitative exploration of the causes of food waste through interviews with students. The assessment included direct measures and weighing of leftover food, and the environmental and economic impact was calculated. A two-level intervention was implemented for students and staff, and a re-assessment of food waste was conducted to evaluate the intervention’s impact. Statistical analysis was performed using SPSS.ResultsThe study monitored 26 meals, finding that the total amount of food waste in the university canteens was (mean = 60.65 g/person), and the intervention reduced food waste by 16.35% per meal (50.73 g/person). Moreover, after the intervention, the amount of food waste costs and total water waste were reduced by 30.14% and 16.66%, respectively. Grey water was reduced significantly by 12.5% (p = 0.033). Interviews with students identified low-quality meals, unpleasant taste, large portions, and a limited menu as the main causes of food waste.ConclusionsIt is possible to tackle food waste effectively with educational intervention, decreasing portion size, and improving the quality and variety of food.