Recycled Water Research Articles

Two-stage continuous cultivation of microalgae overexpressing cytochrome P450 improves nitrogen and antibiotics removal from livestock and poultry wastewater.

Improper treatment of livestock and poultry wastewater (LPWW) rich in ammonium nitrogen (NH4-N) and antibiotics leads to eutrophication, and contributes to the risk of creating drug-resistant pathogens. The design-build-test-learn strategy was used to engineer a continuous process using Chlorella vulgaris to remove NH4-N and antibiotics. The optimized system removed NH4-N at a rate of 306mg/L/d, degraded 99% of lincomycin, and reduced the hydraulic retention time to 4days. The physiological, metabolic, and genetic mechanisms used by microalgae to tolerate LPWW, remove NH4-N, and degrade antibiotics were elucidated. A new cytochrome P450 enzyme important for NH4-N and antibiotic removal was identified. Finally, application of synthetic biology improved the NH4-N removal rate to 470mg/L/d, which is the highest removal rate using microalgae reported to date. This research contributes to the mechanistic understanding of wastewater detoxification by microalgae, and the goal of achieving a circular bioeconomy for nutrient and water recycling.

Balanced water and heat energy recycling by full evaporation of wastewater (FEW) in dry biorefining processes of lignocellulose biomass.

Lignocellulosic biorefinery technology requires minimum energy consumption and wastewater generation to overcome challenges in industrial applications. This study established a rigorous model and a comprehensive physical property database of dry biorefining process on Aspen Plus platform for production including L-lactic acid, citric acid, sodium sugar acids, amino acid, and ethanol based on the experimental data. Full evaporation of wastewater (FEW) approach was proposed to completely replaced the external steam supply, and significantly reduced the freshwater input by 67% ∼ 85% and wastewater generation by 64% ∼ 89%, depending on the specific products. The carbon-neutral heat energy from lignin residue combustion generates an extra heat output of 1.098∼4.772 GJ per ton of dry wheat straw (DW) after all the heat energy needs of the biorefinery process and FEW treatments are satisfied, equivalent to a reduction of 0.219∼0.952kg CO2 eq/kg DM emission. This study provided a self-consistent solution for water and energy balance in biorefinery processes.

Evaluating oomycete pathogen and community responses to chemical- and Slow Sand Filtration-based water treatment strategies to enable water recycling in nursery production systems.

While recycling irrigation water can reduce water use constraints and costs in nurseries, adoption is hindered by the associated risk of recirculating and spreading waterborne pathogens. To enable regional water re-use, this study assessed oomycete re-circulation risks and recycled water treatment efficacy at organismal and community scales. In culture-based analysis of recycled pond water at two Mid-Atlantic nurseries across three years, diverse oomycetes (12+ species) were detected using culture-based analysis, with Phytopythium helicoides as the dominant species; MiSeq analysis detected eight of these species, plus 24 additional taxa. Oomycete contamination risk and detection abilities in recycled water was highest in fall and/or spring based on species richness (P = 0.001). Four species, Pythium oopapillum, Pythium aff. diclinum, Phytophthora cryptogea-complex and Phytopythium helicoides were pathogenic to seedlings (90% damping off) and mature chrysanthemum plants, causing decline in more plants than negative controls (P = 0.025)-these species thus represented the known pathogen targets for recaptured water treatment. Slow Sand Filtration (SSF) of recaptured water resulted in an 85% or greater reduction in oomycete recovery from baits across months, although detection in greenhouse water following treatment indicated re-introduction challenges. MiSeq analysis indicated that SSF altered relative species abundances, which decreased for two species and increased for three species, including one putative pathogen, post-SSF (P < 0.05). Chlorine treatment reduced recovery of oomycetes from baits by at least 75%, although diversity increased, as did relative abundance of several species including one putative pathogen (P < 0.05). Together these results indicate that SSF and chlorination have potential efficacy in enabling irrigation water recycling in nursery production, although system modifications are needed to improve treatment efficacy and prevent pathogen re-introduction post-treatment.

Precipitation recycling impacts on runoff in arid regions of China and Mongolia: a machine learning approach

This study analyses the impact of precipitation recycling on runoff in the China Mongolia Arid Region (CMAR) using ERA5 data and a Random Forest model. We address the challenge of quantifying complex precipitation recycling effects in arid regions by combining reanalysis data with machine learning. Our approach reveals significant positive feedback between precipitation recycling rate (rr) and runoff (ro), with correlation coefficients of 0.40 in spring and 0.21 in summer. Scenario analyses demonstrate that neglecting rr underestimates runoff by 11-23% in wet seasons, while doubling rr overestimates it by 8-19% during peak rainfall. The Random Forest model effectively captures rr-ro relationships, particularly for prevalent low runoff conditions in CMAR. These findings emphasize the crucial role of local water recycling in sustaining runoff and managing water scarcity in arid regions. We suggest incorporating recycling processes into hydrological models to improve runoff predictions in water-scarce environments.

Towards stormwater reuse risk management plans: Methodology and catchment scale evaluation of QMRA.

The reuse of stormwater represents a potential option for meeting water demands in water stressed regions as well as preventing and mitigating diffuse pollution of receiving water bodies. Particularly, the elaboration of a risk management plan for stormwater reuse may help to understand associated environmental and public health risks and design fit-for-purpose water treatment processes. In this work, it is presented an innovative methodology to perform quantitative microbial risk assessment (QMRA) for stormwater reuse by using data simulated by SWMM software. Particularly, 210 rain events were simulated by SWMM after qualitative and quantitative calibration of the sewer network model of the city of Cupra Maritima (Italy) to identify sewer overflows. Obtained concentrations of pathogens (i.e., E. coli, Campylobacter) in overflows from each critical spillway were fitted by theoretical distribution curves. Hence, QMRA for Campylobacter was performed by Monte Carlo simulation and by linking observed overflows to the exposure events of stormwater reuse for the scenario of 1) municipal irrigation, 2) garden irrigation and 3) toilet flushing as defined by the Australian Guideline for water recycling. Furthermore, QMRA analysis was repeated after simulation of sewer overflow treatment by nature-based solution (NBS) with and without disinfection (UV and performic acid - PFA). Stormwater treatments were simulated by applying uniform distributions of expected range of bacteria log removals. Results showed that stormwater treatment by nature-based solution and disinfections (PFA dose of 2.5-5mg/L) were able to reduce the risk of Campylobacter infection to acceptable level for most of spillways in the three investigated reuse scenarios. In addition, produced data were elaborated to identify critical overflows discharging in bathing water according to the indications of the EU bathing directive.

Advantages and disadvantages of current human enteric virus surrogates in soils and aquifers.

Groundwater is one of the main sources of drinking water, thus, human enteric viruses in groundwater could pose safety risks. Many enteric viruses enter drinking water sources through irrigation or recharge of contaminated water. It is therefore advised to test the potential transport risk with harmless surrogates before wastewater or recycled water is used for irrigation or groundwater recharge. An ideal virus surrogate should be able to mimic the particle size, the surface properties and the inactivation rate of its target virus and should be easy to detect. Particle size should be the first consideration when selecting a suitable virus surrogate in soil and aquifer. The natural bacteriophages could only mimic the viruses that are inherently similar to themselves, and there is only a limited number of readily available bacteriophages. Therefore, once a certain bacteriophage is chosen for study, its particle size, surface properties and inactivation rate are set and unmodifiable for the experiment. Fluorescent microspheres <200nm could surrogate target viruses in fast-flow subsurface systems, where inactivation can be neglected. However, the current detection limit of fluorescent nanospheres cannot support the detection of small-sized fluorescent microspheres (∼20nm) through porous media without macropores. Newly emerging DNA tracers not only allow controlling the size and surface properties, but also offer a low detection limit (ideally 1 copy of DNA). Investigating new types of DNA tracers that could either simulate or mimic the inactivation rate of target viruses could widen the use of virus surrogates to study groundwater contamination and drinking water supply safety.

Pro-Environmental Behaviors and Their Limitations in A Sample of Chilean Adults

Objective: To analyze pro-environmental behaviors (PEB), their level of awareness, and the limitations that reduce their frequency. Secondary objectives included evaluating the psychometric properties of the instrument used and examining gender differences across the dimensions analyzed. Theoretical Framework: Climate change is the main challenge of our time. To mitigate its negative impact, it is essential to promote PEB, defined as actions that effectively contribute to environmental protection. These behaviors can be grouped into five dimensions: recycling, sustainable mobility, energy and water conservation at home, environmentally responsible purchasing, and social and political participation for environmental purposes. Method: A mixed-method descriptive design was employed with non-probabilistic sampling. The “Characterization of Pro-Environmental Behaviors Survey (ECCP)” and open-ended questions about limitations were administered to 284 participants. Analyses included factorial analysis, descriptive statistics, group comparisons, and emergent coding of qualitative data. Results and Conclusions: The ECCP demonstrated adequate psychometric properties. Participants reported being aware of the relationship between PEB and environmental protection. The most frequent dimensions were energy and water conservation, recycling, and sustainable mobility, while environmentally responsible purchasing and social/political participation were less common. The main limitations identified were lack of time, insufficient infrastructure, comfort, and habit, with differences observed across specific dimensions. Originality/Value: The findings provide insights into the prevalence of pro-environmental behaviors and their limitations, offering valuable information for the targeted development of strategies to promote these behaviors effectively.

Sustainable Urban Water Resource Management in China: Challenges and Innovations

Rapid urbanization in China has led to severe challenges in urban water resource management, including water scarcity, pollution, and the impacts of climate change. This study examines innovative technologies such as water recycling, rainwater harvesting, and urban green infrastructure, focusing on their implementation in major cities like Beijing, Shenzhen, and Guangzhou. Through case studies and data analysis, the research evaluates the effectiveness of these solutions in addressing the pressing water management issues. The findings suggest that integrated water management strategies, supported by strong policy frameworks and public involvement, are critical for achieving sustainable urban water systems. The study concludes with recommendations for improving urban resilience to water-related challenges in the face of ongoing climate and demographic pressures.

Membrane Treatment to Improve Water Recycling in an Italian Textile District.

The textile district of Prato (Italy) has developed a wastewater recycling system of considerable scale. The reclaimed wastewater is characterized by high levels of hardness (32 °F on average), which precludes its direct reuse in numerous wet textile processes (e.g., textile dyeing). Consequently, these companies utilize ion exchange resins for water softening. However, the regeneration of the resins results in an increased concentration of chlorides in the reclaimed wastewater that exceeds the limit set by Italian regulations for the reuse of water for irrigation purposes. The objective of this study is to investigate the potential of membrane filtration as an alternative method for removing hardness from water. Therefore, an industrial-scale ultrafiltration-nanofiltration (UF-NF) pilot plant was installed to test the rejection of hardness from the reclaimed wastewater. The experiment employed two types of NF membranes and three permeate fluxes (27, 35, and 38 L·m-2·h-1) for testing. The results demonstrated that the system could remove hardness with efficiencies exceeding 98% under all conditions tested. The experimental findings indicate that the UF-NF system has the potential to be employed as a post-treatment step to render the reclaimed wastewater suitable for all textile finishing processes and to expand the scope for reuse.

Formulation and evaluation of the effective microorganisms in sewage treatment.

Effective microorganisms pose a great potential in wastewater treatment. In the present study, effective microorganisms' formulations were developed using different organic substrates that support the growth of more beneficial microorganisms for sewage treatment. Based on the metagenomic analysis and biochemical profile information, the fish waste-based effective microorganisms' formulation was identified as the effective formulation. Metagenomic analysis showed that fish-based effective microorganisms' formulation had the Lactobacillus and Acetobacter groups of bacteria. The dominant groups were Lactobacillus pontis (64.85%), Acetobacter aceti (8.92%), and Lactobacillus reuteri (8.98%). The developed fish waste-based effective microorganisms' formulation was used to treat the sewage water with different concentrations. Effective microorganisms' formulation at 3% showed appreciable results. It recorded a significant reduction in BOD from 389.2 to 117.9mg L-1 and COD from 820.5 to 257.1mg L-1 in 96h. It also significantly decreased the concentration of ammoniacal and nitrate nitrogen, phosphorus, sulphate, and coliforms. Besides, the effective microorganisms' formulation ensured the reduced level of odour from sewage water. Therefore, we can effectively use the effective microorganisms' formulation for sewage water treatment and recycling.

Urban Agriculture and Water Recycling: A Comprehensive Outlook on Current Panorama

Urban Agriculture and Water Recycling: A Comprehensive Outlook on Current Panorama

Water sorption performance of the zeolitic metal azolate framework MAF-7.

Water sorption isotherms of [Zn(mtz)2]n (MAF-7) were collected over a wide temperature range (15-45 °C) and its water sorption performance was assessed in terms of water uptake, sorption kinetics, recyclability, and regeneration temperature. Additionally, molecular simulations were conducted to elucidate the locations of water molecules within the pore cavity of MAF-7.

Identifying dehydration-induced shear velocity anomaly in the Earth's core-mantle boundary.

The steep temperature gradient near the bottom of the mantle is known to generate a negative correlation between the shear wave velocity (V S ) and the depth in most regions of the D″ layer, as detected by seismological observations. However, increasing V S with depth is observed at the D″ layer beneath Central America, where the Farallon slab sinks, and the origin of this anomaly has not been well constrained. Here, we calculate the thermoelastic constants and obtain the elastic wave velocities of hydrous phase H with various Al contents and cation configurations, which may act as a water carrier to the D″ layer. We find its V S to be substantially lower than the post-perovskite-type bridgmanite. The dehydration of Al-enriched phase H and the redistribution of Al from the hydrous component to dry silicates would gradually raise the V S below the top of the D″ layer. The presence of 3.5 wt% water is sufficient to compensate for the thermal effects to match the seismic anomaly at the bottom of the mantle beneath Central America. The positive slope of V S versus depth in the D″ layer may fingerprint deep water recycling.

Minimizing Process Water and Energy Consumption in Styrene Production by Ethylbenzene Dehydrogenation

Styrene is a crucial unsaturated aromatic monomer with a wide range of industrial applications. Styrene production faces several problems where the water supply and energy usage are keep increasing. Process modifications were implemented to minimize process water and to optimize the energy consumption. The modification uses Aspen HYSYS simulation by replacing coolers and heaters with heat exchanger and implementing water recycling system. Aspen HYSYS simulations show these changes reduce water usage by 89.8% and significantly decrease energy consumption up to 54.69%. This modification shows the water and energy usage have been significantly reduced than the basic process. Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Environmental Indicators for Assessment of Circular Economy (CE) Implementation in the Water and Wastewater Sector

ABSTRACTWater and wastewater sector actively participates in circular economy (CE) transition; however, there is no official CE monitoring framework to measure the level of progress toward the CE model in this sector. The paper presents a set of environmental indicators that could support water and wastewater treatment companies in the assessment of CE implementation. CE indicators were grouped into six areas of CE implementation in this sector: reduction—prevention of wastewater generation; reclamation (removal)—contamination removal from water and wastewater; reuse—water reuse for nonpotable usage; recycling—water reuse for potable usage; recovery—recovery of raw materials and energy from water‐based waste; and rethink—rethinking use of raw materials. The following indicators were proposed in specific CE areas: reduction—tap water consumption reduction, wastewater generation reduction, waste reduction, sewage sludge generation reduction, and water footprint; reclamation—pollutants removal from water and pollutants removal from wastewater; reuse—water reuse from wastewater for nonpotable usage and recycling of technical water for nonpotable usage; recycling—water reuse from wastewater for potable usage; recovery—raw materials recovery, bio‐based fertilizers, energy recovery, processing of sewage sludge, composting of sewage sludge, biogas production, and processing of ashes; and rethink—CE technologies, life cycle assessment reports, CE products, and CE business models, industrial symbiosis, and carbon footprint. The proposed CE indicators can be used not only to assess the level of transformation toward CE but also to support further policies on strategic CE initiatives in organizations operating in the water and wastewater sector. Moreover, they could support the strategic planning of further CE initiatives in organizations. The proposed list of CE indicators is not closed because in the coming years, more and more CE solutions are expected to be developed and implemented in water and wastewater treatment plant companies, involving also economic and social aspects, in order to support the sustainable development.

A Comprehensive Evaluation of Water-Saving Society Construction in Xinxiang, Henan Province, China

Water is a crucial and fundamental resource. It is well known that agricultural cultivation, industrial production, and human daily life are not possible without water. Efficiently utilizing water resources is of great significance for achieving global Sustainable Development Goals (SDGs). In order to improve water use efficiency in various industries and promote water-saving development, China has been implementing water-saving society construction since 2002. Henan Province is the main grain-producing area in China, with wheat production accounting for a quarter of the country’s total. As the core area of “Central Plains Agricultural Valley” in Henan Province, Xinxiang City plays an important role in agricultural technology innovation and agricultural production. However, Xinxiang City is facing problems of water scarcity and pollution, which constrain the sustainability of agricultural production. Therefore, building a water-saving society can solve the current water problems faced by Xinxiang City and ensure the sustainable development of the economy and society. This study built an evaluation index system for water-saving society construction in Xinxiang, Henan Province, China. The proposed evaluation index system includes 20 evaluation indices from six aspects—integrated, agricultural water, industrial water, domestic water, water ecology and environment, and water-saving management—and then divides its development level into several stages. The Analytical Hierarchy Process (AHP) was adopted to calculate the index weight. Then, a comprehensive evaluation model for water-saving society construction in Xinxiang City was established by combining it with grey relative analysis (GRA). The results showed that the overall level of water-saving society construction in Xinxiang City is in the excellent stage, whereas water consumption per CNY 10,000 of GDP, the effective utilization coefficient of irrigation water, the reuse rate of industrial water, and the leakage rate of urban water supply network are all in the good stage. However, the urban recycled water utilization rate is still in the poor stage. These research results can effectively and reasonably reflect the development level of water-saving society construction in Xinxiang City and guide the continued implementation of water-saving society construction. At the same time, the comprehensive evaluation of water-saving society construction helps to formulate and adjust water resource management policies and measures; it also holds significant value for sustainable water management and combating water scarcity.

Evaluating sustainable water management strategies using TOPSIS and fuzzy TOPSIS methods

This study evaluates sustainable water management strategies using TOPSIS and Fuzzy TOPSIS (FTOPSIS) to address global water scarcity by comparing rainwater harvesting, water recycling, and desalination across five criteria: water efficiency, cost-effectiveness, environmental impact, social equity, and technological feasibility. The results show Rainwater Harvesting as the most balanced option with a relative closeness value of Ci+=0.640, excelling in social equity and environmental sustainability. Water Recycling ranks closely behind (Ci+=0.608), highlighting its adaptability and technological feasibility, while Desalination, though highly efficient, is hindered by lower cost-effectiveness (Ci+=0.578). By integrating TOPSIS and FTOPSIS, the study addresses uncertainties and subjective criteria, providing a robust multi-dimensional assessment framework for resource management. This methodology aids decision-makers in identifying strategies that align with sustainable development goals and adapt to regional priorities. Future work can expand this framework to include stakeholder engagement and policy factors, enhancing water management strategies for resilient, long-term solutions.

A high-resolution multi-scale industrial water use dataset in China

Water is crucial for achieving the UN Sustainable Development Goals, particularly SDG 6. As a major source of water use and pollution, industrial sector requires improved water management based on more systematic and refined analysis. Such analysis, however, is compromised by the accuracy, granularity, and coverage of industrial water data. Here we present an open dataset of China’s industrial water use, compiled from 1,480,265 plant-level reports. This high-resolution multi-scale dataset offers unparalleled details, supporting multi-scale analysis at the province, city, and county levels, and across 2-digit, 3-digit, and 4-digit industrial classifications. It provides comprehensive information on water use, recycling, pollution, and wastewater processing. Such data enables further macro- and micro-level analysis, including multi-regional input-output analysis, structural decomposition analysis, statistical analysis, machine learning, as well as many other advanced analytical methods. This dataset can equip researchers and policymakers with a valuable tool to advance sustainable water management, fostering alignment with global sustainability goals.

Tradeoff optimization of urban roof systems oriented to food-water-energy nexus

Urban roof development serve as a form of urban tinkering that could provide favorable conditions to meet wicked food, water, and energy challenges. In this research, three urban roof systems are designed featuring food production, rainwater collection, building energy saving, and photovoltaic power generation, which are named the bare roof system, green roof system, and open-air farming roof system. Here we establish a generalizable framework to reveal the multifaceted tradeoffs of urban roof schemes integrating geographic information system, life cycle assessment, and multi-objective optimization and decision-making. Testing the framework in a typical compact city Shenzhen, China, results show that the rooftop suitability for food-water-energy function development within the city ranges from 26.21 % to 42.83 %. When implementing a city-wide roof system upscaling, the harvested rainwater on rooftops would contribute to 82.5 % of urban recycled water utilization target in 2035 and exhibit the fewest economic costs, but comes at the cost of life cycle carbon emissions and land occupation with 1850 kt and 140 km2. City-wide roof farming scenario shows potential to achieve the local self-sufficiency of vegetables, and stands out as the avoided transboundary energy footprints which are 4.5 times greater than life cycle energy consumption. Our research can foster the multiple tradeoff understanding between upscaling roof systems and urban food-water-energy nexus. The findings will assist in multi-objective decision-making for roof planning and sustainable transition in cities.

Achieving zero liquid discharge through water recycle in Muara Karang Combine Cycle Power Plant

Abstract The study evaluates a water recycling program implemented at the Muara Karang Power Plant (MKPP), which plays a crucial role in reducing wastewater and enhancing the operational efficiency of the power plant. Water is an essential resource in power generation, but its quality has been declining over time, impacting plant performance. Regular checks on the boiler water at MKPP reveal that the plant collects around 1-1.4 m3/second, which was traditionally discarded after inspection. However, considering the quality and quantity of this water, the study explores its potential for recycling. Since 2023, approximately 2,741.46 m3 of water has been reused, improving efficiency by 160 m3 per month while reducing wastewater discharge. The program demonstrates that simple yet strategic water management interventions can significantly improve operational efficiency and environmental sustainability in power plants. By recycling boiler water within the system, the plant conserves valuable water resources and lowers pollution levels. This study introduces a pioneering approach to water recycling in power plant by utilizing boiler water that was previously discarded. This innovative approach not only reduces the environmental impact but also sets a new benchmark for sustainable water management in the energy sector, providing a model for other power plants to follow.