Greywater Research Articles

Addressing water scarcity in agricultural irrigation: By exploring alternative water resources for sustainable irrigated agriculture

AbstractThis review paper addresses challenges in the water sector, particularly in irrigated agriculture, aiming to propose solutions for meeting irrigation demands while promoting global food security and sustainable development, notably SDG 6. Structured around three facets: empowering farmers, strengthening conventional sources of irrigation water and harnessing non‐conventional water resources, it emphasizes the significance of exploring blue water resources due to precipitation variability. Many irrigation systems operate below efficiency, offering productivity enhancement opportunities. Water management in agriculture spans various levels, involving farmers as key stakeholders. In addition to surface water, alternative sources like rainwater, grey water, recycled wastewater and groundwater can meet irrigation needs. Rainfed agriculture, facing challenges from erratic rainfall, can benefit from rainwater harvesting and under‐irrigation practices. Wastewater emerges as a pivotal resource, particularly in periurban areas, necessitating appropriate safety measures. This paper presents the General Report of Congress Question 64 of the ICID Congress in Visakhapatnam. It provides a unique opportunity to focus on how alternative water resources might enhance the resilience of irrigation systems and bridge the gap between water supply and demand. The subdivision of the paper into three distinct subtopics guides research contributions, encouraging responses that delve into the specific themes of reinforcing, harnessing and empowering, all within the context of sustainable irrigated agriculture.

Multi-Objective Design of a Horizontal Flow Subsurface Wetland

An artificial wetland is used to treat gray, waste, storm or industrial water. This is an engineering system that uses natural functions of vegetation, soil and organisms to provide secondary treatment to gray water. In the physical design of each artificial wetland, there are various action factors that must meet certain characteristics so that the level of gray-water pollution is reduced. In this sense, several design methodologies have been developed and reported in the literature, but some are customized designs and often do not meet the required decontamination objectives. This challenge increases as the complexity of the task in its structure also increases. Particularly in this work, a multi-objective evolutionary algorithm is used to optimize the physical design of a horizontal flow subsurface wetland (HFSW) for gray-water treatment. The study aims to achieve two objectives: first, to minimize the physical volume, and second, to maximize the contaminant removal efficiency. The defined objective functions depend on six design variables called hydraulic retention time, width, length, water depth inside the wetland, substrate depth and slope. Three constraint functions are also defined: removal efficiency greater than 95%, physical volume below 500 m3 and compliance with a length–width ratio is 3:1, varying the population size and number of generations equal to 200, 400, and 600. The set of solutions according to the number of generations as well as the Pareto front corresponds to the best solution that complies with the constraints of the problem of oversizing the HFSW, and the Pareto front shows the interaction between the objectives and their behavior, reflecting the problem’s nature as minimization–maximization.

Analysis of Physical Properties of Grey water from Residential Buildings

One way to conserve water is to find a safe way to use it further than formerly. Grey water recycling is now accepted as sustainable result to the general increase of the fresh water demand. Grey water refers to water that has formerly been used in some way but which can be reused or reclaimed in order to conserve fresh water. It's considered fairly simple to treat slate water to make it safe for public use because of lower situations of pollutants. The treatment of slate water from domestic structures is a critical process for sustainable water operation. This study outlines a comprehensive methodology, beginning with a thorough feasibility assessment, including considerations of available space, original regulations, and propinquity to water exercise points. Analysis of on- point slate water characteristics informs the design of an effective treatment system, incorporating source separation, pre-filtration, natural treatment, filtration, disinfection ,storehouse ,and distribution .Construction emphasizes flawless integration with being structure, and performance testing ensures system optimization. Clear operating procedures, regular monitoring, and compliance reviews contribute to ongoing success. Community education enterprise play a vital part in promoting responsible water operation. This holistic approach, combining specialized effectiveness, environmental responsibility, and community engagement, demonstrates a sustainable model for slate water treatment in domestic settings.

Decentralized greywater treatment for reuse: a cost – benefit study for knowledge-based urban development (KBUD) Parks

Os sistemas de tratamento descentralizado são uma alternativa às tradicionais estações centralizadas, que tratam os efluentes domésticos nas grandes cidades. A descentralização é importante em áreas distantes do centro da cidade e pode facilitar o reúso em um mesmo edifício, transformando o local em uma região mais sustentável. Esses sistemas podem ser bem aplicados em Parques de Desenvolvimento Urbano Baseado em Conhecimento (KBUD), principalmente os de quarta geração, que também consideram o meio ambiente como uma pedra fundamental do desenvolvimento. Assim, nosso objetivo foi verificar a viabilidade do sistema descentralizado de tratamento de água cinza para produzir água não potável a ser reutilizada em um escritório no International Hub for Sustainable Development (HIDS), um KBUD de quarta geração. Em uma revisão bibliográfica, o Wetland foi considerado a melhor opção e a análise de custo-benefício foi realizada. A estimativa de demanda e produção de água cinza (inclui água de fontes como pias, chuveiros, banheiras, máquinas de lavar e utensílios de cozinha, exceto a água de vasos sanitários) foi baseada em dados coletados em campo nos departamentos da Universidade de Campinas (UNICAMP). Como resultado, o sistema foi projetado para tratar 135 m³ de água por mês, levando a uma economia de 22,65 m³ de água por mês. A economia mensal será de US$ 415. Com base nas estimativas de custo, a economia gerada recuperaria o investimento inicial do sistema em menos de três meses de uso, com uma taxa interna de retorno (TIR) de 34,9% em um ano. Assim, o custo-benefício é substancial, uma vez que o retorno do investimento é rápido. Portanto, o sistema é viável e interessante do ponto de vista sustentável.

The simultaneous removal of methylene blue (MB) and Ca2+ by recyclable adsorbents based the scales derived from coal gasification system.

The transformation of solid wastes from industrial production into effective adsorbents could significantly contribute to wastewater treatment. In this study, after acidizing and burning soft scale (SS) from coal gasification system, two magnetic adsorbents (mag-ASS and mag-BASS) were prepared via the combination of magnetite with ultrasonic, respectively. The treatment effects of mag-ASS and mag-BASS were then investigated for simulated wastewater containing macromolecular organic matter [i.e., methylene blue (MB)] and Ca2+. The results indicated that the pseudosecondorder kinetic, Elovich, Freundlich,Langmuir and Temkin model could well describe the adsorption behavior of MB and Ca2+ onto mag-ASS and mag-BASS. The maximum adsorption capacities of mag-ASS for MB and mag-BASS for Ca2+ were 600.53mg/g and 102.54mg/g, respectively. Surprisingly, the adsorption abilities of mag-ASS for MB and mag-BASS for Ca2+ showsignificantly higher than the others. The adsorption mechanisms of MB mainly included electrostatic interaction, π-π conjugate interaction and cation exchange, while those of Ca2+ were mainly electrostatic interaction and cation exchange. The diffusion of MB and Ca2+ onto the magnetic adsorbents might be controlled by the combined effects of intraparticle and liquid film diffusion. There was no significant reduction in adsorption capacity after 8 cycles of adsorptionand desorption, indicating that SS-based magnetic adsorbents had good recyclability and stability. Moreover, the removal efficiency of mag-BASS for total hardness and total organic carbon in real coal gasification gray water (CGGW) was 82.60 and 64.10%, respectively. The treatment of CGGW and theresource of wastes would significantly promote the reasonable disposal of coal gasification scales.

Water Footprint: A Review Based on Concepts, Methods, and Implications

Water footprint assessment has become a useful method for assessing how much water is used by products and activities related to humans, offering insights into how water resources might be managed sustainably. While agricultural production accounts for the majority of water consumption worldwide, the industrial and residential sectors also use large amounts of water and cause pollution. This review article provides an examination of the approaches and uses of water footprint assessment in a range of industries and geographical areas. The notion of water footprint and its elements green, blue, and grey water footprints as well as the corresponding computation techniques are introduced at the outset of the work. The most recent developments in spatially explicit modelling and life cycle assessment techniques, it examines the development of water footprint assessment procedures. The paper explores the many uses of water footprint assessment, from consumer items and urban water management to industrial operations and agricultural output. It provides case studies and real-world examples that show how water footprint analysis may be applied practically to address issues with pollution, water shortages, and sustainability in various settings. The study also looks at the difficulties and constraints that come with assessing the water footprint, such as methodological uncertainty, data availability, and temporal and geographical variability. It talks about current studies as well as potential paths forward for improving the reliability and usability of water footprint measurement instruments. As a comprehensive and integrated method for measuring and controlling the effects of human-induced water usage on regional and global water resources, this study concludes by highlighting the importance of water footprint assessment. In order to promote sustainable water management practices, it highlights the necessity of multidisciplinary collaboration and stakeholder involvement. Keyword: Water Footprint, Sustainability, Life Cycle Assessment, Spatial Analysis.

A Framework for Assessing Food Baskets Based on Water and Carbon Footprints

The composition of food baskets can significantly influence the water consumption rate and society’s environmental impact. This study evaluates the sustainability of Iran’s food and nutrition security by evaluating five food baskets using water and carbon-footprint indices. These food baskets are the common Iranian food basket (CIFB), the vegetarian food basket (VFB), the Ministry of Health desired food basket (MHDFB), the Swiss Society for Nutrition food basket (SSNFB), and the Mediterranean food basket (MFB). This study also examines the role of Iran’s agricultural sector under the Paris Climate Change Agreement (COP21). The TOPSIS multi-criteria decision-making method was used to identify the most desirable food basket. The results of this study show that the VFB could be the most desirable alternative to the CIFB. Replacing the CIFB with the VFB causes a 10% and 21% lower water and carbon footprint, respectively. From a 30-year perspective (around 2050), choosing the VFB would reduce the blue water footprint by 19.7 BCM and the gray water footprint by 3.6 BCM compared to the CIFB. According to the provisions of COP21 regarding Iran’s voluntary program to reduce greenhouse gas emissions, the agricultural sector will be one of the sources of greenhouse gas emissions that will face an upward trend. Hence, to adhere to this voluntary commitment, these emissions should be reduced by changing the CIFB to the VFB or reducing emissions in other sectors, such as industry. Choosing the VFB can reduce 10.7 million tons of CO2 emissions, which can be a significant step for the agricultural sector in Iran in reducing greenhouse gas emissions. Overall, considering the characteristics of farm products (water and carbon footprints) in Iran, a country located in a semi-arid climate, the VFB is recommended.

Grey water footprint model of heavy metal based on the hazard quotient

The traditional Grey Water Footprint (GWF) model, rooted in the assumption that the hazard of each pollutant is independent, faces a limitation when dealing with heavy metals, whose hazards to aquatic organisms accumulate. The objective of this study is to develop a GWF model that reflects the cumulative threat posed by heavy metals to aquatic organisms, using the Hazard Quotient (HQ) as a foundation. The model comprises three parts: (i) defining the minimum virtual water volume required to control the HQ within the allowable limits, which includes long-term GWF (L-GWF) and short-term GWF (S-GWF); (ii) calculating the hazard level of heavy metal pollution (HHL); and (iii) determining the contribution rates of each heavy metal to L-GWF and S-GWF. The evaluation results of the heavy metal pollution discharged from the Guixi Smelter show that (i) The GWF of heavy metals from the Guixi Smelter decreases dramatically in 2014, with L-GWF and S-GWF of 2.39 and 0.22 billion m3, respectively, which are only 49.9 % and 47.1 % of L-GWF and S-GWF in 2013. (ii) The HHL values in 2012 and 2013 are 1.52 and 1.43, respectively, with a grade of “moderate.” In contrast, the HHL values in 2014 and 2015 significantly decrease to 0.82 and 0.74, respectively, both with a grade of “low”. (iii) The L-GWF contributors of heavy metals in the Guixi Smelter are Cu > Cd > Pb, and the S-GWF contributors are Cu > Pb > Cd > As. (iv) The GWF model based on HQ overcomes the limitations of conventional GWF and provides an effective assessment of the cumulative heavy metal hazards to aquatic organisms.

Decoupling Agricultural Grey Water Footprint from Economic Growth in the Yellow River Basin

Decoupling agricultural economic growth from agricultural water pollution is of great importance to regional sustainable development. It is necessary to further explore the decoupling state and key driving factors connecting agricultural water pollution and agricultural economic growth on the basis of accurate measurement of agricultural water pollution. Accordingly, taking the Yellow River Basin (YRB) as the research object, this study combined the water footprint theory, the Logarithmic Mean Divisia Index (LMDI) model and the Tapio decoupling model (TDM) to conduct an in-depth decoupling analysis of the connection between the agricultural grey water footprint (AGWF) and agricultural economic growth in the YRB. Specifically, this study first calculated the AGWF of the YRB during 2016–2021 and objectively evaluated the water resource utilization in this region based on the AGWF. Then, the LMDI model was used to explore the driving factors of the AGWF in the YRB. Finally, the decoupling states between the AGWF and its driving factors with agricultural GDP (AGDP) were studied using the TDM. The main results are as follows: (1) The overall AGWF in the YRB showed a decreasing trend and a slow increase, decreasing by 5.39% in 2021 compared to 2016. (2) The primary promoting factor and inhibiting factor of AGWF reduction are the efficiency effect and agricultural economic effect, respectively. (3) The decoupling states of the AGWF and AGDP presented strong decoupling (SD) and then weak decoupling (WD) in the YRB during the research period. The decoupling states between the agricultural grey water footprint intensity (AGWFI) and AGDP changed from expansive negative decoupling (END) to SD. The decoupling state of population and AGDP remained SD. This study will contribute to alleviating agricultural water pollution in the YRB and help policymakers in water-stressed countries to formulate agricultural water management policies.

From shower to table: fate of organic micropollutants in hydroponic systems for greywater treatment and lettuce cultivation

ABSTRACT This study evaluated the dual functionality of hydroponic systems to grow edible crops while treating greywater (GW) containing 20 organic micropollutants (OMPs). Various conditions with differing nutrient contents were tested: raw GW, GW with struvite, and GW with commercial nutrient solution. System performance was assessed with plant growth and standard parameters and OMP removal. After 4-week exposure, all conditions produced healthy-looking plants, proving GW as a viable hydroponic growth medium. However, only the condition with commercial solution yielded plants comparable to the biotic control, indicating the necessity of nutrient supplementation. Effluent from conditions with well-developed plants met the requirements of the European water reuse legislation (EU 2020/741) for scenarios B–D (food crops not in direct contact with the reclaimed water and industrial crops), and had the highest OMP removal, showcasing the effectiveness of the system for OMP treatment. Estimated calculations of OMP detected in leaves (10/20 OMP detected, predominantly positive and small) resulted in calculated potential human health risks through lettuce intake for two compounds: atenolol and epoxycarbamazepine. These findings support a continued evaluation of the behavior of other OMPs and their transformation products in water–plant systems, and their consideration in legislation on water reuse and food safety.

Synthesis and characterization of novel D‐mannitol based hydrogel: Swelling and adsorption behavior of heavy metal ion studies

AbstractA highly efficient hydrogel derived from D‐Mannitol xanthate has been successfully synthesized using a free‐radical solution copolymerization technique. An equimolar mixture of acrylonitrile (AN) and acrylic acid (AA) has been reacted with D‐Mannitol xanthate (DMX) under inert atmosphere. Three distinct grades of D‐Mannitol xanthate‐based hydrogels viz. DMXHGs‐1, DMXHGs‐2, and DMXHGs‐3, were prepared. Extensive analyses were conducted on the hydrogels using various methods such as UV, FT‐IR, SEM, XRD, GPC, TGA and ΔpHPZC. The maximum swelling ratio of DMXHGs‐3 was found to be 52122%, 50434% and 48576% for 24 h with water retention ratio of 80.98%, 78.64% and 79.22% for 30 h in distilled, tap and gray water respectively. These findings indicate the DMXHGs‐3 hydrogel has remarkable swelling and water retention capacity. Comprehensive investigations were carried out to evaluate the hydrogel's remarkable adsorption capacity to act as an adsorbent for effectively removing hazardous metal ions. The highest removal percentages of 95.5% and 94.4% and maximum adsorption capacities of 523.56 mg g−1 and 462.96 mg g−1 were observed with DMXHGs‐3 hydrogel for Cu2+ and Co2+ ions, respectively. Metal ion removal experiments were conducted by varying several parameters including dosage, pH, temperature, concentration, and time. The quantification of Cu2+ and Co2+ was accomplished using UV–visible spectroscopy. Present studies demonstrate the suitability of D‐mannitol xanthate‐based hydrogels for the efficient removal of toxic metal ions from wastewater.

Enhancing Greywater Treatment for Sustainable Irrigation: Utilizing Natural Filtration Materials and SMBR Technology

Enhancing Greywater Treatment for Sustainable Irrigation: Utilizing Natural Filtration Materials and SMBR Technology

Effects of new-type urbanization on resource pressure: Evidence from a water-energy-food system perspective in China

To address the resource and environmental challenges posed by rapid urbanization, China has devised and executed the strategy of new-type urbanization (NU). This study aims to discuss the effects of NU on resource pressure in view of the water-energy-food (WEF) system. Taking 30 provinces in China from 2006 to 2020 as samples, this paper firstly establishes a comprehensive evaluation indicator system of NU from the population, economic, spatial, social and eco-environmental dimensions, and assesses the level of NU using the entropy weight method. Secondly, this paper uses the gray water footprint as a measurement indicator, innovatively integrating water quality into the WEF system for assessing WEF system pressure (WEFSP). Finally, the impact of NU on WEFSP is explored based on the panel fixed effects model. The findings revealed: (1) There is an inverted “U-shaped” relationship between NU and WEFSP, and China's current level of NU has exceeded the Environmental Kuznets Curve (EKC) threshold. (2) The impact of NU on WEFSP exhibits significant regional heterogeneity, with a significant impact in the eastern region. (3) NU consistently exacerbates regional water stress when water quality is considered, indicating that sustainable urban water management practices are essential. (4) The subdimensions of NU indicate that population and social urbanization are important factors that exacerbate the WEFSP, while economic and spatial urbanization reduce the WEFSP. The research results help to clarify the impact of NU on the WEFSP and provide a reference for the timely adjustment and optimization of NU policies to achieve effective resource management and regional sustainable development.

Features of the anatomy of the right half of the heart in the common Gogol (Bucephala clangula)

The common goldeneye (Bucephala clangula) is a sea duck that belongs to the order Anseriformes and the family Anatidae. Due to their lifestyle, they are able to hold their breath for up to 30 minutes and dive to a depth of 10 meters. Such a load on the duck’s body contributes not only to the restructuring of morphological structures, but also to increased heart function. An analysis of the sources showed that the morphology of the heart in mammals and birds has been studied, but no work on the morphology of the right half of the heart in the common goldeneye was found, which was the purpose of our study. The material was hearts from male common goldeneye – 1.5-2 years old (n=3), caught in the bay of the Angara River. Thus, the cardiac index in the common goldeneye was determined to be 83%, and the presence of epicardial fat was noted on the side of the coronary and paroconal sulcus. The right ventricle is located above the level of the apex of the left ventricle, and 70.7% surrounds the borders of the left ventricle. The free appendages of the atrium are formed with the participation of eight pectineal muscles, which in the form of a ridge begin from the muscular valve, and dorsomedially closer to the atrial sinus, become thinner and unite at one point. The length of the pectineal muscle’s ranges at 8.2±0.54 mm, thickness 0.83±0.02 mm. The right ventricle is separated from the atrium by a muscular valve, which has its own characteristics of fastening, where its high part extends from the level of the subsinus groove (interventricular septum), forms the parietal part of the atrioventricular orifice and at the level of the vascular cone narrows slightly and is fixed in two parts to the wall of the ventricle. On the side of the right ventricle, trabeculae are expressed only under the muscular valve, where the crossbars are directed from left to right and downward, from its narrowing. The crossbars are 6.9±0.23 long and 0.83±0.03 mm wide, with jumpers up to 1 mm.

Grey water footprint for evaluating Zefta wastewater treatment plant: a case study

ABSTRACT The numbers of wastewater treatment plants (WWTP) in Egypt are increasing, yet the general level of pollution associated with wastewater discharge after treatment has not been evaluated. Grey water footprint (GWF) was used to assess the effluent discharges from Zefta WWTP. GWF, before and after treatment, was calculated and followed up to determine its impact on the receiving freshwater body. 150 samples were collected and analysed for BOD5 to determine the optimum operating conditions. Averages values were DO = 2.2, SV30 = 500, SVI = 167, SA = 9.3 d, MLVSS = 2392 mg/L, f/m = 0.16, MLSS in RAS = 7922 mg/L, WAS = 140 m3/d and the HRT = 12 h. The removal efficiency of COD and TSS in the primary settling tank reached 39% and 69%, respectively. Average calculations of removal efficiency percentile reached 90-93%. Average freshwater quantities required to reduce pollutants in the receiving body stream were seasonally determined for Zefta WWTP as 5.3 × 107 m3/year. The average influent BOD5 was 376 mg/L, it was reduced to 47 mg/L in the effluent, wherever the Cmin is 6 mg/L and Cnat is 10 mg/L. Statistical analysis has shown a significant direct relation between ΔWFG,mef and WFG,ref reached 0.952 and a significant inverse relation with Cef −0.982. WFG,T has shown a significant direct relation with Cr 0.974. WFG,T– ref has shown a significant direct relation with Cr as 0.971 and WFG,T as 0.803. It can be concluded that ΔWF is effective in evaluating the efficiency of wastewater treatment and its effect on the quality of receiving water bodies.

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

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

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

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

New approach to domestic grey water footprinting: country-scale accounting using statistical methods in Türkiye

ABSTRACT This study aimed to develop an approach for country-scale domestic grey water footprint (GWFdomestic) accounting and examine spatio-temporal differences using statistical methods. In this scope, the GWFdomestic was calculated as the amount of water required to reduce the total nitrogen concentrations of domestic wastewater released into receiving media from 81 cities in Türkiye. GWFdomestic values were estimated based on the data on wastewater amount and applied wastewater treatment process. GWFdomestic was calculated by dividing the pollutant load of discharged water by the critical concentration in the surface water. The empirical results showed that (a) the produced wastewater amount increased up to 125 m3/year in some cities. (b) GWFdomestic values showed a difference between 330 and 1,900 depending on the level of treatment, and the average value was about 750 m3/ca.year. (c) A total of 81 cities were grouped under four categories, and applied water treatment technology was the main characteristic of this classification. (f) GWFdomestic has not statistically significantly changed over time in a large part of the country. It can be concluded that country-scale GWFdomestic accounting can assist water managers in developing prevention measures by analyzing spatio-temporal differences in the water footprint of domestic discharges.

Multi-Objective Optimization of the Planting Industry in Jiangsu Province and Analysis of Its “Water-Energy-Carbon” Characteristics

The modern development of the planting industry needs to not only ensure food supply but also to consider social and environmental issues. This poses higher demands for rational planning of planting structures to achieve green development while meeting demands and conserving resources. Therefore, this paper takes Jiangsu Province as a representative case, accounting for and analyzing the water footprint, energy consumption, and carbon emissions of seven major crops. Based on this analysis, a multi-objective planning model is established to explore the optimization of its planting structure. The results show that: (1) from 2010 to 2020, the overall water footprint of these seven crops in Jiangsu Province initially increased and then decreased, while energy consumption showed a fluctuating upward trend; (2) carbon emissions from planting in Jiangsu Province initially increased and then fluctuated downward over time, and exhibited significant spatial clustering characteristics, with overall emissions being higher in northern Jiangsu, followed by central Jiangsu, and then southern Jiangsu; (3) the optimization results indicate that economic benefits increased by 4.06%, while the carbon emission and grey water footprints decreased by 3.78% and 7.62%, respectively, resulting in comprehensive improvements in economic and ecological benefits. This study can provide theoretical support for adjusting the planting structure in crop-producing areas and promoting the green and sustainable development of the planting industry.

Exploring effects of carbon, nitrogen, and phosphorus on greywater treatment by polyculture microalgae using response surface methodology and machine learning

The microalgae-based wastewater treatment is a promising technique that contribute to achieving sustainable development goals (SDGs), such as SDG-6, “Clean Water and Sanitation”. However, it is strongly influenced by the initial composition of wastewater. In this study, the impact of initial organics and nutrient concentration on the removal of total organic carbon (TOC), total carbon (TC), ammonium (NH4+), total nitrogen (TN), and phosphate (PO43−) from greywater using native polyculture microalgae was explored. Response surface methodology was employed along with two machine learning approaches, AdaBoost and XGBoost, to evaluate the interactions among three main factors: TOC, NH4+, and PO43−, and their effects on treatment efficiency. The C/N ratios for achieving maximum TOC and TC removal efficiency of 99.2% and 97.7% were determined to be 10.3, and 65.4–73.6, respectively. Notably, the N/P ratio did not significantly affect their removal. The highest NH4+ removal efficiency, reaching 96.2%, was attained at C/N ratios of 4.3, 24.0, 38.2, and 212.9, coupled with N/P ratios of 0.3, 2.6, and 23.4. Highest TN removal efficiency of 77.2% was achieved at C/N and N/P ratios of 12.2 and 2.0, respectively. Highest PO43− removal of 78.8% was obtained at N/P ratio 12.8. However, C/N ratio did not affect the removal efficiency. Maintaining these specified C/N and N/P ratios in the influent greywater would ensure that the treated greywater meets the required standards for various reuse applications, including flushing, groundwater recharge, and surface water discharge. The integration of RSM with AdaBoost and XGBoost provided accurate predictions of removal efficiencies. For all the models, XGBoost had the highest R2, and lowest MAE and MSE values. The cross validation of RSM models with AdaBoost and XGBoost further reinforced the reliability of these models in predicting treatment outcomes.