Sewage Treatment Research Articles

The Impacts of Cellulose on Volatile Fatty Acid Production and the Microbial Community in Anaerobic Fermentation of Sludge at High and Medium Temperatures.

During large-scale sewage treatment, a large amount of excessive sludge is produced, which will cause serious pollution in the environment. In recent years, anaerobic digestion technology has been widely promoted because it can achieve better sludge reduction, and the products and byproducts after anaerobic digestion can be fully utilized as resources. In this study, cellulose was added as the co-fermentation substrate during the fermentation process at 30 ℃ and 50 ℃ to enhance the production of VFAs. The result indicated that cellulose could significantly increase the yield of VFAs in both 30 ℃ and 50 ℃. Meanwhile, COD and reducing sugar generation in the fermentation process were also measure. Analysis of the microbial community structure at the class and genus levels revealed that the proportion of several genus closely related with cellulose degradation such as Cellvibrio, Fibrobacter, and Sporocytophaga were significantly increased with the addition of cellulose. Co-fermentation was recognized as an economic and environmental friendly strategy for sludge and other solid waste treatment. The analysis of the effect of cellulose as a substrate on the production of VFAs at high and medium temperatures is highly important for exploring ways to increase the production of VFAs in anaerobic fermentation.

Plant transpiration inspired biomass-derived solar evaporator for highly efficient solar vapor generation

The interface solar evaporation is an energy-saving and environmentally friendly method for seawater desalination and sewage purification. In this work, a biomimetic solar evaporator (ppy@AZL) inspired by plant transpiration was designed to achieve high efficient vapor generation. The ppy@AZL evaporator was made of zizania latifolia as raw material, has a cellulose skeleton with high water transport after alkalization and was decorated with photothermal polypyrrole to form bionic branches and leaves, and has excellent photothermal conversion performance. The evaporation performance and potential application of ppy@AZL evaporator in seawater desalination and sewage treatment were studied. The results indicated that the average evaporation rate of the ppy@AZL in simulated seawater (3.5 wt%) under the irradiation of one sun (1 kW m−2) was 2.239 kg m−2 h−1, and the photothermal conversion efficiency was 93.4 % in this work. In addition, the ppy@AZL evaporator has excellent evaporation rate of 2.668 kg m−2 h−1 in 9 h outdoor continuous evaporation experiment of simulated seawater (3.5 wt%), and can continuously and stably generate vapor. Therefore, this study provided a new solar evaporator with low-cost, simple preparation, better salt resistance, and high evaporation performance for seawater desalination and sewage treatment.

Effectiveness of cyclic treatment of municipal wastewater by Tetradesmus obliquus – Loofah biofilm, its internal community changes and potential for resource utilization

Microalgae biofilm has garnered significant attention from researchers in the field of sewage treatment due to its advantages such as ease of collection and stable sewage treatment capabilities. Using agricultural waste as biofilm carriers has become a hotspot in reducing costs for this method. This study first combined Tetradesmus obliquus with loofah to form a microalgae biofilm for the study of periodic nitrogen and phosphorus removal from municipal wastewater. The biofilm could stably treat 7 batches of wastewater within one month. The removal rate of TP almost reached 100 %, while the removal rates of NH4+ and TN both reached or exceeded 80 %. The average biomass yield over 25 days was 102.04 mg/L/day. The polysaccharide content increased from 8.61 % to 16.98 % during the cyclic cultivation. The lipid content gradually decreased from 40.91 to 26.1 %. The protein content increased from 32.93 % in the initial stage to 41.18 % and then decreased to 36.31 % in the later stage. During the mid-stage of culturing, the richness of anaerobic bacteria decreased, while the richness of aerobic and facultative bacteria increased, which was conducive to the construction of the microalgae-bacteria symbiotic system and steadily improved the effect of nitrogen and phosphorus removal. As the culturing progressed, the Rotifers that emerged during the mid-stage gradually damaged the biofilm over time, leading to a decline in the effectiveness of sewage treatment in the later stages. This study offers technical support for carrier selection in microalgae biofilm methods and for the periodic removal of nitrogen and phosphorus from wastewater.

Nitrogen recovery from biogas slurry with high ammonia nitrogen concentration through struvite precipitation utilizing acid leaching solution of collophanite tailings

ABSTRACT The high concentration of ammonia nitrogen (NH4+) and chemical oxygen demand (COD) in biogas slurry pose great challenges to the efficiency of traditional wastewater treatment systems. Collophanite tailings are solid waste, characterized by significant concentrations of phosphorus (PO43-) and magnesium (Mg2+), represent a potential resource for the reduction and recovery of NH4+ in biogas slurry via struvite precipitation. This study systematically explored the optimal leaching parameters employing sulfuric acid for the extraction of PO43− and Mg2+ from collophanite tailings. The effect of [PO43-]:[NH4+] molar ratio and pH on the recovery of NH4+ in biogas slurry was investigated. The physicochemical properties of the precipitates were confirmed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and chemical analysis. Results suggested that the highest removal efficiency of NH4+ (88.5%) was achieved when employing a [PO43-]:[NH4+] molar ratio of 1.0 at pH 9.5. Evaluation of effluent quality demonstrates a significant enhancement in the biodegradability of the treated biogas slurry, evidenced by an increase in the COD/TN ratio increased from 2.1 to 10.4. Economic analysis shows that the net income would be approximately 21.33 USD/m3 for proposed produces. These findings underscore the potential of utilizing collophanite tailings for NH4+ recovery from biogas slurry.

Comprehensive assessment of the water environment carrying capacity based on machine learning

Human activities and climate change are constantly threatening water environment systems. To alleviate pressure on the water environment and meet the requirements for sustainable societal development, it has become important to study the water environment carrying capacity (WECC). As science and technology have advanced, the use of artificial intelligence has penetrated various disciplines, and the application of machine learning has achieved many good results in the environmental sciences; however, little attention has been given to the WECC. To this end, a WECC assessment model was developed based on a variety of machine learning algorithms, to provide a novel approach and better understanding of the WECC. In this study, 13 natural and anthropogenic factors related to the water environment system in Liaoning Province (China) were selected, and the study period ranged from 2015 to 2019. Four basic machine learning algorithms, namely, random forest (RF), support vector machine (SVM), multilayer perceptron (MLP) and k-nearest neighbour (KNN), were used for batch modelling, and stacking was carried out based on the output results. A comparison and screening of the models revealed that RF and the stacking model had the best model prediction performances. Because RF was relatively simple and convenient, a comprehensive assessment of the regional WECC based on this algorithm was carried out. The results showed that most of the control units with an overloaded WECC are located in the central and northern regions of Liaoning Province, and the control units of overloading can be well identified and the trend of regional WECC status can be observed. To improve model transparency, we also performed an explanatory analysis based on the shapley additive explanations (SHAP). The results showed that precipitation, soil texture, sewage treatment plant, wind speed, and temperature were the most important factors influencing the water environment system. Precipitation is the most influential factor, and with increasing rainfall, the WECC first improves and then gradually deteriorates. For the anthropogenic factors, the WECC generally improves first and then worsens as these factors increase. These research results can be used to provide a powerful and practical new methodology for the comprehensive assessment of the WECC and provide a basis for the development of water environment policies and regulatory implementation in the region.

EVALUATING WASTEWATER TREATMENT EFFICIENCY OF MEDICAL CENTERS IN BINH DUONG PROVINCE

This paper presents a comprehensive analysis of the wastewater management system implemented at a medical center located within the Bau Bang Industrial Park in Binh Duong province, Vietnam. With a staff of 166 and 60 beds, the facility operates in accordance with TCVN 4470:2012 General Hospital design standards, serving a diverse range of water demands including domestic, medical, and auxiliary requirements. The wastewater management system is meticulously designed to handle both rainwater and wastewater separately. Rainwater is efficiently collected through surface and roof drainage networks, while domestic and medical wastewater undergo discrete collection processes. The medical center's wastewater treatment facility, operating at a capacity of 100 m³/day, employs a multistage treatment process to ensure compliance with stringent regulatory standards (QCVN 28:2010/BTNMT, column B, K = 1). This process includes preliminary treatment, anaerobic and aerobic biological treatment, membrane filtration, and disinfection. The facility consistently meets quality parameters outlined in QCVN 28:2010/BTNMT, exhibiting effective removal rates for organic pollutants, suspended solids, ammonia, phosphates, and pathogens. Furthermore, the medical center demonstrates commendable environmental stewardship through its stormwater drainage infrastructure, which integrates seamlessly with the local drainage network, safeguarding against environmental contamination. Overall, the wastewater management practices at the medical center exemplify best practices in environmental management within the healthcare sector. This study provides valuable insights into the design, implementation, and performance evaluation of wastewater treatment systems in industrial settings, contributing to the global discourse on sustainable wastewater management practices.

SUITABILITY OF THE HOSPITAL WASTEWATER TREATMENT SYSTEM IN BINH DUONG PROVINCE TO THE ENVIRONMENTAL CARRYING CAPACITY

As the number of healthcare facilities increases, stringent management of wastewater treatment systems becomes imperative. This study investigates a wastewater treatment system designed for a general clinic in Bình Dương Province, Vietnam, which complies with Vietnamese environmental standards. The clinic, located in Bến Cát City, serves approximately 200 patients per day and generates an average wastewater volume of 1.7m³/day. The treatment system, with a capacity of 10m³/day, employs a combination of biological and chemical methods, including anoxic and aerobic processes, to efficiently reduce pollutants. Results indicate that the treated wastewater meets the QCVN 28:2010/BTNMT, column A standards, ensuring minimal environmental impact when discharged into the Thi Tinh River. The study demonstrates the system's effectiveness in managing hospital wastewater, contributing to environmental protection and public health.

Insights into the efficient removal and mechanism of NiFeAl-LDH with abundant hydroxyl to activate peroxymonosulfate for sulfamethoxazole wastewater

Layered double hydroxide (LDH) material with abundant OH was successfully prepared by co-precipitation method, and a water purification system of Ni2Fe0.25Al0.75-LDH activated peroxymonosulfate (PMS) was constructed to rapidly degrade sulfamethoxazole (SMX) pollutants. The optimal conditions for the degradation of SMX in the system were as follows: 0.30 g/L Ni2Fe0.25Al0.75-LDH, 0.30 mM PMS, pH = 7 and 90 % SMX was removed in 10 min and almost completely in 40 min, which was consistent with the predicted results of response surface methodology (RSM) analysis. The abundant OH in Ni2Fe0.25Al0.75-LDH could form M(O)OSO3 complexes with PMS, accelerating the generation of reactive oxygen species (ROS) and promoting the removal of SMX. Quenching experiments and electron paramagnetic resonance (EPR) spectra showed that SO4−, OH, O2− and 1O2 also existed in the system. The surface-bound SO4− and O2− contributed greatly to the removal of SMX and the electron transfer between metals was also conducive to the production of active substances. The possible degradation pathways and intermediates of SMX were proposed. The toxicity assessment software tool (T.E.S.T) and total organic carbon (TOC) results indicated that the Ni2Fe0.25Al0.75-LDH/PMS system could reduce the overall environmental risk of SMX to some extent. This study provided a new strategy for the practical application of heterogeneous catalysts in sewage treatment.

Evaluation of a Greenhouse Ecosystem to Treat Craft Beverage Wastewater

An aerated greenhouse ecosystem, often referred to as a Living Machine®, is a technology for biological wastewater treatment within a greenhouse structure that uses plants with their roots submerged in the wastewater. This system has a small footprint relative to traditional onsite wastewater treatment systems and constructed wetland, can treat high-strength wastewater, and can provide a high level of treatment to allow for reuse for purposes such as irrigation, toilet flushing, and landscape irrigation. Synthetic and actual craft beverage wastewaters (wastewater from wineries, breweries, and cideries) were examined for their treatability in bench-scale greenhouse ecosystems. The tested wastewater was high strength with chemical oxygen demands (COD) concentrations of 1120 to 15,000 mg/L, total nitrogen (TN) concentrations of 3 to 45 mg/L, and total phosphorus (TP) concentrations of 2.3 to 90 mg/L. The COD, TN, and TP concentrations after treatment ranged from below 125 to 560 mg/L, 1.5 to 15 mg/L, and below 0.25 to 7.8 mg/L, respectively. The results confirm the ability of the aerated greenhouse ecosystem to be a viable treatment system for craft beverage wastewater and it is estimated to require 54 and 26% lower hydraulic retention time than an aerobic lagoon and a low temperature, constructed wetland, respectively, the types of systems that would likely be used for this type of wastewater for onsite locations.

In-depth performance evaluation of an innovative halophyte-based multistage constructed wetland- microbial fuel cell for the treatment of brackish sewage

Constructed wetland-microbial fuel cells (CW-MFC) can be the future of sustainable wastewater management. This study developed a multistage CW-MFC based on the halophyte Juncus ridigus for treating brackish sewage. Its treatment efficiency was compared with a multistage constructed wetland without electrodes (CW) and a control (C), which had neither electrodes nor plants. The CW-MFC showed significantly higher removal efficiency for COD, BOD, PO43--P, NH4+-N, NO2–-N, and NO3–-N, with removal efficiency of 81 %, 88 %, 83.58 %, 90.75 %, 80.96 %, and 78.75 %, respectively. Up to a 40.6 % decrease in salinity was observed in CW-MFC, followed by CW and C. Plant absorption and electrode adsorption were the primary mechanisms for removing major salt-contributing ions and elements like Cl-, SO42-, Na, Mg, and Ca. It was further confirmed by their increased deposits in plant tissues and electrodes, as revealed by SEM-EDX. A second-order kinetic model was used to investigate the efficiency of the CW-MFC system regarding pollutant removal. CW-MFC efficiently removed several emerging contaminants from sewage, including phenol, 3,5-bis(1,1-dimethyl ethyl)-, which was also found to be accumulated in the shoots of J. ridigus. Plants in CW experienced stress, as evidenced by lower biomass (47.47 % lower than CW-MFC) and decreased chlorophyll content (20 %), whereas in CW-MFC, they were extremely healthy. Interestingly, CW-MFC had a higher bacterial population than CW, which indicates increased microbial activity. CW-MFC was found to be the most efficient treatment system as it alleviated plant stress and increased bioaccumulation and microbial activity for treating brackish sewage.

Integrated Modeling of Flow, Soil Erosion, and Nutrient Dynamics in a Regional Watershed: Assessing Natural and Human‐Induced Impacts

AbstractCurrent integrated modeling frameworks for simulating nutrient sources and dynamics are inadequate for large regional watersheds dominated by groundwater‐surface water interactions due to their simplistic representations of groundwater. In this study, we develop a coupled model that integrates comprehensive surface water, 3‐D groundwater, soil erosion, and nutrient processes. The model is intended to enhance the understanding of nutrient dynamics and sources in the Pearl River Basin (PRB). The model exhibits satisfactory performance in simulating streamflow and sediment transport patterns, capturing essential seasonal variations in water quality indicators. Hydrological budget assessments from 2002 to 2020 in the PRB reveal that 54% of precipitation drains into the South China Sea as surface water, while groundwater discharge as baseflow accounts for 18% of the streamflow. The nutrient budget for the PRB indicates that non‐point sources are the dominant contributors to both nitrogen (N) and phosphorus (P), ranging between 64% and 90%. Improved sewage collection and treatment have reduced point source nutrient contributions over the evaluation period. Groundwater remains a significant and consistent source of N, contributing between 11% and 19%. Natural disturbances and fertilization have led to an upward trend in river N inputs, while afforestation and sewage reduction efforts have resulted in a downward trend in river P inputs. Increased fertilization emerges as a central concern for the PRB, suggesting cost‐effective mitigation of fertilizer usage a pragmatic solution. The coupled simulation model developed in this study offers a novel systems approach for basin‐wide nutrient analysis and pollution control strategies, considering both natural and human‐induced disturbances.

Removal of Organic Contaminants in On-Site Wastewater Treatment Systems: The Role of Sorption and Transformation

Removal of Organic Contaminants in On-Site Wastewater Treatment Systems: The Role of Sorption and Transformation

Comprehensive vulnerability assessment for environmental facility depending on spatial characteristics in South Korea

Among environmental facilities, wastewater treatment facilities have a crucial role in sustaining human life, and any occurrence of an earthquake or flood within these facilities can result in various social, economic, and environmental issues, either directly or indirectly. Therefore, a quantitative vulnerability assessment of wastewater treatment facilities is necessary to minimize and prevent damage from earthquakes and flood disasters. For this reason, this study introduces a novel indicator to assess the susceptibility of disasters, considering aspects of exposure, sensitivity, and adaptive capacity. The newly proposed indicator encompasses numerous evaluation criteria, topography, natural surroundings, hydraulic systems, structural composition, and non-structural features. Also, Weights derived using the combined weight calculation (CWC) method, which combined the analytic hierarchy process (AHP) and entropy weight method were applied to the indicator. It was tested across 23 cities to validate its efficacy, revealing a substantial correlation between the vulnerability index and the specific attributes of the city's wastewater treatment facilities. Therefore, this study analyzed wastewater treatment facilities by comparing the attributes of the urban areas under investigation, such as topological characteristics, urbanization levels, population density, infrastructure quality, and disaster preparedness resources available. The suggested methodology can facilitate the development of strategies aimed at averting damage caused by earthquakes or floods and reducing the adverse impact on wastewater treatment facilities while considering the unique characteristics of the urban setting in question.

Synchrotron induced X-ray fluorescence spectroscopy reveals heavy metal translocation in sludge amended soil-plant systems: assessment of ecological and health risks.

The use of composted sludge from sewage treatment plants as a soil amendment is a common practice of recycling nutrients like organic carbon, nitrogen, and phosphorus. The sewage generated in larger cities of developing countries is often contaminated with various heavy metals (HMs) that ultimately end up in composted sludge. Thus, using such composted sludge is likely to pose ecological and human health risks. Hence, the knowledge of HM translocation in sludge-soil-plant systems is of vital importance. The present study was aimed at investigating the HM translocation in sludge-soil-plant system. The HM translocation was measured using synchrotron radiation-induced x-ray fluorescence spectrometry and atomic absorption spectroscopic techniques. The results indicated high HM mobility (up to 2628.5mgkg-1) from sludge to spinach plant. The metal accumulation (mgkg-1) ranged in the order-Fe (950.55-2628.5) > Zn (20.11-172.13) > Cu (13.86-136.17) > Mn (2.13-34.67) > Cd (0.11-31.17) > Pb (1.50-30.16) > Co (0.18-9.85) As (0.02-7.80) > Cr (0.01-5.69). This observed accumulation depended on the volume of sewage being treated in the sewage treatment plant (STP) and varied in the order control < (8 MLD Bhagwanpur, STP 1) < (80 MLD Dinapur, STP2) < (140 MLD Dinapur, STP3) hence the HM load coming into STPs. The metal transfer factor, bioconcentration factor, and translocation factor values also correlated with the abundance of Fe, Cu, Pb, Cd, and Zn in spinach root and shoot compartments. The carcinogenic risk for heavy metal carcinogens like As, Cd, Cr, and Pb revealed children being more prone to cancer upon spinach consumption. Hence, it is necessary to assess the heavy metals present in the sludge prior to its application in agricultural fields.

Toxicity standards of biosolid leachate

Sewage treatment in Brazilian cities generates biosolids that can be useful in the agricultural field, although they pose contamination risks to the environment and to human health. Ecotoxicity tests are essential to ensure the safety of such a use, since they assess biosolids’ toxicity in the soil and in water. The aim of the current study is to assess biosolids leachate phytotoxicity by using lettuce seeds. In order to do so, Petri dishes were used to incubate the seeds, which received the biosolids leachate and remained under controlled temperature conditions, in the dark, for 168 hours. Overall, the herein assessed parameters have evidenced that the biosolids leachate diluted up to 60% had positive effect on (i.e., it stimulated) seedling growth and germination. However, phytotoxic effect was observed when it was applied without any dilution, since it reduced seed germination and growth parameters. Therefore, the lower the leachate concentration, the higher the Lactuca sativa root growth, a fact that highlights the phytotoxic effect of this leachate.

Planar Group Functionalization of Quasi-Discrete Pores in Metal-Organic Frameworks for Enhanced Isomeric Separation in Simulated Moving Bed Processes.

The efficient separation of 4-methyl-1-pentene (4MP1) from its structural isomers is crucial for industrial applications but remains challenging due to the similar physicochemical properties of these compounds. This study introduces a novel strategy using metal-organic frameworks (MOFs), specifically an engineered variant of ZIF-108, which demonstrates remarkable improvements in the thermodynamic and kinetic properties for 4MP1 separation. By substituting the methyl groups in ZIF-8 with planar nitro groups, we achieved a strategic resizing of the pore windows and cavity dimensions in ZIF-108. This adjustment not only enhanced the molecular affinity and selectivity toward 4MP1 but also facilitated a diffusion rate that is 164 times faster than that observed in ZIF-8. These properties significantly elevated the performance of ZIF-108 in simulated moving bed (SMB) processes, achieving up to 96.5% recovery of high-purity 4MP1, outperforming traditional adsorbents. Comprehensive characterization, including density functional theory (DFT) calculations and molecular dynamics (MD) simulations, provided insights into the interactions and the stability of the adsorption process. The findings suggest that the strategic modification of the pore architecture in MOFs holds significant potential for optimizing the separation processes of industrially relevant mixtures.

Performance prediction of sludge volume index of oxygenic photogranule based wastewater treatment system using machine learning algorithms

Oxygenic Photogranulation is a novel biotechnology that treats wastewater without external aeration and produces biomass in dense photogranules with high settling velocities. Oxygenic photogranules (OPG) based wastewater treatment (WWT) faces challenges during scaleup due to its dynamic and complex system variables, making troubleshooting costly. The Machine Learning (ML) approach can address this issue by creating a WWT process simulation. Moreover, traditional mechanistic models do not capture the interaction between input and output features due to their high dimensionality and the non-linear relationship, making them computationally expensive. In this study, the two-stage feature selection (FS) method is studied to enhance the prediction performance of SVI30, a critical operational parameter, to ensure optimal settleability and minimal loss of active photogranules. The optimal feature subsets generated by the two-stage selection method were evaluated using four regression models: decision tree, random forest, gradient boosting, and extreme gradient boosting. Results indicate that, among all regression models, the decision tree performs well having a prediction efficiency of 85 % with the subset of features obtained after Recursive Feature Elimination (RFE) of decision tree features in the second stage. This indicates the effectiveness of the two-stage FS method in identifying the most relevant features for predicting SVI30. The structured approach of FS and model evaluation highlights the potential of ML in addressing complex operational challenges in OPG WWT operations.

Offset integrity reduces environmental risk: Using lessons from biodiversity and carbon offsetting to inform water quality offsetting in the catchments of the Great Barrier Reef

Environmental offsetting has been developed as a mechanism to facilitate the benefits from economic development while avoiding or minimizing environmental harm. This is achieved by compensating for environmental impacts at one location by generating equivalent environmental improvements elsewhere. However, experience with biodiversity and carbon offsetting indicates it can be difficult to ensure the integrity of offsets. Under recent legislation in the catchments of the Great Barrier Reef (GBR), Australia, it is mandatory for water quality emissions from new or expanded point source development to be offset by reducing pollution elsewhere, frequently through reducing non-point source pollution (NPSP). Therefore, informed by experience with biodiversity and carbon offsetting, we summarised sources of uncertainty in NPSP reduction that would influence water quality offset integrity; estimated the maximum potential demand for water quality offsets from sewage treatment plants, the largest point source emitter of total nitrogen (TN) in the GBR catchments, between 2018 and 2050; and discussed the implications of both on the ability of offsetting to counterbalance the impact of economic development in catchments where nitrogen loads have a large influence on the health of important GBR ecosystems. The catchments surrounding the population centres of Cairns and Mackay had both a potentially high future demand for nitrogen water quality offsets and nitrogen loads with a strong influence on the health of the GBR. Consequently, any low integrity water quality offsets in these catchments could jeopardise progress toward the water quality improvements needed to ensure the continued health of the GBR. Water quality offsetting has numerous strengths as a policy instrument however substantial uncertainties remain related to environmental outcomes. Until further research can reduce these uncertainties, water quality offsets that are implemented near increased point source emissions and have a high certainty of effectiveness may provide a balance between scientific rigour and policy workability.

On-site monitoring and numerical simulation on groundwater flow and pollution plume evolution in a hexavalent-chromium contaminated site

Accurately ascertaining spatiotemporal distribution of pollution plume is critical for evaluating the effectiveness of remediation technologies and environmental risks associated with contaminated sites. This study concentrated on a typical Cr(VI) contaminated smelter being currently remediated using pump-and-treat (PAT) technology. Long-term on-site monitoring data revealed that two highly polluted regions with Cr(VI) concentrations of 162.9 mg/L and 234.5 mg/L existed within the contaminated site, corresponding to previous chromium slag yard and sewage treatment plant, respectively. The PAT technology showed significant removal performance in these highly polluted areas (>160 mg/L) after six months of pumping, ultimately achieving complete removal of the pollutants in these high-pollution areas. Numerical simulation results showed that although the current remediation scheme significantly reduced the Cr(VI) pollution degree, it did not effectively prevent the incursion of the pollution plume into the downstream residential area after 20 years. Additionally, an improved measure involving supplementary pumping wells was proposed, and its remediation effects were quantitatively evaluated. Results indicated that the environmental pollution risk of groundwater downstream could be effectively mitigated by adding pumping wells, resulting in a reduction of the pollution area by 20 % in the case of adding an internal well and 41 % with the addition of external wells after 20 years. The findings obtained in this study will provide an important reference and theoretical guidance for the reliability analysis and design improvement of the PAT remediation project.

Characterizations of Interfacial Solar Water Evaporation

Interfacial solar water evaporation has emerged as an effective technique for converting solar energy to thermal energy, which can then be applied to clean water production and sewage treatment. This review discusses the primary characterization techniques used to evaluate the key aspects of interfacial solar water evaporators: the intrinsic and performance evaluation. Each technique is discussed with a brief explanation of its foundations, followed by carefully selected examples. This review is aimed at assisting materials chemists and physicists, particularly students, in choosing the most appropriate techniques for characterizing photothermal materials.