Calculation of carbon emissions in wastewater treatment and its neutralization measures: A review

Biofilm-Induced Critical Flux in Dead-End Ultrafiltration Processes: Phenomenon, Mechanism, and Economic and Environmental Benefits

The concept of critical flux, introduced by R.W. Field, defines the flux below which the filtration resistance remains constant over time. Notably, this concept, originally for cross-flow filtration, faces challenges in dead-end filtration (the dominant mode used in drinking water ultrafiltration (UF)). Herein, leveraged by regulated membrane biofilms, we proposed a novel biofilm-induced critical flux specific to dead-end filtration. Below this critical flux, the membrane biofilm could act like a cross-flow to maintain mass balances by the biodegradation of foulants, thereby preventing a continuous increase in filtration resistance. Additionally, we demonstrated an optimized strategy to improve the critical flux─backwashing without air scouring, which doubled the critical flux from 6 to 12 L·m-2·h-1. A life cycle analysis revealed that operating at the biofilm-induced critical flux can reduce energy consumption and minimize membrane cleaning, thereby effectively lowering the overall operating costs (52%) and carbon emissions (61%) compared to conventional UF. Sensitivity analysis also indicated that extending membrane life and reducing membrane costs were crucial for lowering overall operating costs, while minimizing fossil energy usage was decisive for reducing carbon emissions. Overall, our study demonstrates that operating at a biofilm-induced critical flux offers a low-maintenance, cost-effective, and environmentally sustainable strategy for drinking water UF.

Carbon source dosage intelligent determination using a multi-feature sensitive back propagation neural network model

The carbon reduction concept drives the development of low-carbon and sustainable wastewater treatment plant (WWTP) operation technologies. In the denitrification stage of WWTPs in China, there are widespread problems of uneconomical dosage consumption and unstable total nitrogen (TN) concentration in effluent through manual experience to add external carbon sources. Deep learning methods can deal with these problems. However, the methods often require a large amount of data. This paper establishes a multi-feature sensitive back propagation neural network (BPNN) based on Shapley additive explanations (SHAP) and sensitivity analysis (MFS-BPNN-SSA) model to predict carbon source dosage in WWTPs and address short-term and limited data. The model also incorporates theoretical formulas to enhance prediction accuracy and feedback regulation to handle anomalous data. The prediction performance of the MFS-BPNN-SSA model surpasses traditional machine learning and deep learning models. R and R2 reach 0.9999, 1.75% and 3.48% higher, respectively, compared to the best-performing traditional model. The model has been operating safely in the WWTP for over two years, achieving a 9% improvement in effluent TN concentration and a 14% reduction in carbon source dosage. This study provides a novel strategy for pollution reduction and carbon mitigation in WWTPs.

Reduction of biogenic CO2 emissions, COD and nutrients in municipal wastewater via mixotrophic co-cultivation of Chlorella vulgaris - aerobic-activated sludge consortium

In this study, biogenic CO2 emissions, COD and other nutrients (i.e. TP, TN and N H 4 + - N ) from aerobic treatment in municipal Wastewater Treatment Plants (WWTP) were quantified and reduced by phycoremediation using a mixotrophic co-cultivation of Chlorella vulgaris and activated sludge. It has been shown that the microalgae sludge consortium (A-ASR, R1) outperformed the normal-activated sludge system (ASR, R2). In fact, estimated biogenic CO2 emissions with algae mark 1.20-fold higher removal, COD marks 1.40-fold higher removal, TP marks 1.70-fold higher removal, and N H 4 + - N marks 1.40-fold higher removal, compared to normal activated sludge (ASR, R2). Meanwhile, due to aeration, N O 3 - - N concentration increased in both reactors because some Ns were oxidized through nitrification. Furthermore, COD increased again during C. vulgaris stationary growth; thus, activated sludge addition every 4 days (optimal time) was implemented to maintain algae-bacteria balance. The results suggest that integrating the treatment of GHG emissions and water pollutants in a single, concurrent process can significantly enhance the sustainability and efficiency of wastewater treatment plants, which has not been explored comprehensively. Finally, by leveraging C. vulgaris capabilities for carbon and nutrients sequestration, this study can provide practical guidance for achieving carbon neutrality in a WWTP.

Achieving efficient autotrophic nitrogen removal in anaerobic membrane bioreactor plus membrane aerated biofilm reactor by regulating nutrient ratios

It is feasible to integrate an anaerobic membrane bioreactor with a membrane aerated biofilm reactor to efficiently implement the sulfate reduction, simultaneous nitrification and autotrophic denitrification process. However, the effect of parameters on nutrient removal and environmental impacts of the process are unclear. In this study, the reactor performance was mainly influenced by the chemical oxygen demand to sulfate (COD/S) ratio and the ammonium to sulfate (N/S) ratio in long-term operation. Significant models were developed to optimize the two factors using the response surface methodology. Under optimal conditions (COD/S ratio of 2.5 and N/S ratio of 0.3), the system could remove above 86 % COD, 99 % ammonium, and 92 % total inorganic nitrogen. Moreover, this process could reduce energy consumption by 30 % and global warming potential by 50 % compared with traditional anaerobic/oxic activated sludge process. These findings provide guidance for the application of this technology in sulfate-containing municipal sewage treatment.

Spatial distribution of heavy metal contamination and risk indices of surface sediments in high-altitude lakes

Lake ecosystems in northern Pakistan are the most critical resources that maintain and regulate water flow for downstream agricultural, domestic, industrial, and ecological processes. One consequence of these processes is that ecosystems deposit heavy metals (HMs), where lake stagnant conditions result in high vulnerability of water resources. For this purpose, the present study examined HMs such as cadmium (Cd), chromium (Cr), cobalt (Co), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) concentrations in high-altitude lakes (HAL) sediments of Mansehra district, northern Pakistan. Sediment samples were collected from the five HAL. This study used HM concentrations in lake sediments for the pollution factors such as contamination factor (Cf), pollution load index (PLI), sediment pollution index (SPI), ecological risk assessment (ERA), and risk index (RI). Among HMs, Fe showed the uppermost levels of 1410 mg/kg in lake sediment, while Cd with lowermost levels of 1.05 mg/kg. Results revealed that most HM concentrations in HAL sediments were within the threshold of sediments quality guidelines (SQGs), except for Cd. Among lakes, the sediments of Siri Lake showed higher contamination of HMs than others. Siri Lake sediments also showed higher Cf, PLI, ERA, and RI values than others. The majority of HMs in HAL sediments showed no contamination, except for Cd (considerable) and Pb (moderate) levels to the exposed aquatic ecosystem. This study revealed that 95% of sediment samples in HAL were noted low to medium-level risks to the exposed aquatic communities. Statistical and geospatial analyses revealed that geogenic sources of contamination are a significant contributor to HM contamination of HAL sediments compared to others.

Designing energy-efficient buildings in urban centers through machine learning and enhanced clean water managements

Rainwater Harvesting (RWH) is increasingly recognized as a vital sustainable practice in urban environments, aimed at enhancing water conservation and reducing energy consumption. This study introduces an innovative integration of nano-composite materials as Silver Nanoparticles (AgNPs) into RWH systems to elevate water treatment efficiency and assess the resulting environmental and energy-saving benefits. Utilizing a regression analysis approach with Support Vector Machines (SVM) and K-Nearest Neighbors (KNN), this study will reach the study objective. In this study, the inputs are building attributes, environmental parameters, sociodemographic factors, and the algorithms SVM and KNN. At the same time, the outputs are predicted energy consumption, visual comfort outcomes, ROC-AUC values, and Kappa Indices. The integration of AgNPs into RWH systems demonstrated substantial environmental and operational benefits, achieving a 57% reduction in microbial content and 20% reductions in both chemical usage and energy consumption. These improvements highlight the potential of AgNPs to enhance water safety and reduce the environmental impact of traditional water treatments, making them a viable alternative for sustainable water management. Additionally, the use of a hybrid SVM-KNN model effectively predicted building energy usage and visual comfort, with high accuracy and precision, underscoring its utility in optimizing urban building environments for sustainability and comfort.

Engineered MXene/Bi2S3 nanoflowers in sodium alginate hydrogel: A synergistic eradicator of disinfected byproducts in aqueous environment

In this work, Bi2S3 nanoflowers were in situ anchored on the surface of Ti3C2 via a hydrothermal process to obtain MXene-supported Ti3C2/Bi2S3 nanocomposite, then incorporated inside in sodium alginate polymer to prepared hydrogel materials (Ti3C2/Bi2S3@SA-H) which outperforms and have an excellent capability for the removal of pollutants like disinfected byproducts. The synthesized hydrogel material Ti3C2/Bi2S3@SA-H may be utilized for a variety of functional materials in environmental applications. Furthermore, the Ti3C2/Bi2S3@SA-H was characterized by SEM, EDX, XRD, BET, AFM, FTIR, Zeta potential, XPS, Raman and TGA. Remarkably, Ti3C2/Bi2S3@SA-H hydrogel 0.007 cm3 g-1, 159.5 nm and 0.0017 cm3 g-1, 160.5 nm materials exhibited the highest average pore diameter. The research focused on evaluating the adsorption capability of Ti3C2/Bi2S3@SA-H hydrogel materials for 2,6-dibromo-4-nitrophenol (DBNP), 2,4,6-triiodophenol (TIP), 2,4,6-Trichlorophenol (TCP) and 2,6-dichloro-4-nitrophenol (DCNP). The findings indicated that the material exhibited the eradication efficiency of about 662, 657, 647 and 617 mg/g from DBNP, TIP, TCP and DCNP respectively. Several adsorption isotherms were extensively examined, encompassing the Temkin, Langmuir and Freundlich models, alongside pseudo-first and second-order models. The Langmuir and pseudo-second-order models showed the highest degree of consistency with the observed data. Concerning regeneration and reusability, the materials demonstrated easy regeneration and effective recyclability over the course of 10 cycles. The notable adsorption capacity, coupled with the innovative combination of Ti3C2/Bi2S3 and polymer hydrogel, along with its recyclability, positions our material Ti3C2/Bi2S3@SA-H as a highly prospective competitors for wastewater treatment and other critical areas in water research.

Analysis of lake changes and their influence factors in the three river regions from 2000 to 2020 in the Sanjiangyuan Region, China

An important factor for investigating climate change in the Sanjiangyuan is the evolution of the spatio-temporal pattern of lakes in this region. The present study used the Google Earth Engine (GEE) platform to extract lakes from 2000 to 2020. The present approach created a lake distribution dataset yearly and analyzed spatial and temporal patterns over 20 years. The analysis of lakes focused on the reaction of the Sanjiangyuan Lakes area to changes in climate, glaciers, and permafrost. The findings indicated that the Sanjiangyuan region contains 143 lakes, the majority of which are predominantly small, measuring 1-10 km2. The small lakes account for 60.14 % of the total and are primarily located in the source regions of the Yangtze River and Yellow River. The findings demonstrated that the Sanjiangyuan lakes experienced a significant expansion over the past two decades, particularly from 2011 to 2020. These lakes are divided into expanded, atrophic, and stable categories. Expanded lakes showed significant inter-annual trends in expansion, while atrophic lakes showed smaller fluctuations. The area of stable lakes experienced a consistent decline after 2010, despite a consistent expansion tendency from 2001 to 2010. Moreover, the results indicated that alterations in the size of glaciers and ice reserves in the Sanjiangyuan region have had the greatest influence on the fluctuation in lake area. Among the factors that affect the climate, temperature had the most significant effect on the change in lake area, followed by precipitation.

Seasonal variation and human health risk assessment of potentially toxic elements in pharmaceutical effluents around Ilorin metropolis, Nigeria

Potentially toxic elements (PTEs) are widely released into the environment as a result of increased urban and industrial development in recent years. The bulk of PTEs are cancer-causing and harm human health by producing free radicals. As a result, it is crucial to monitor, evaluate, and limit the effects of the elements on human health. In this study, levels of PTEs (As, Cr, Cd, Ni, Co, and Pb) in pharmaceutical effluents discharged along the Asa River around the Ilorin metropolis and their seasonal variations were evaluated. Water samples were collected from eight different locations over a two-season period along the river and analyzed for PTEs using atomic absorption spectrophotometry and an inductively coupled plasma optical emission spectrometer. As, Cd, Pb, Cr, Ni, and Co had mean PTE values in the effluents (both seasons) of 0.0258, 0.0233, 0.00193, 0.0176, and 0.0164 mg/L, respectively, with As and Pb surpassing the WHO standard. Maximum temperature and pH were measured for the physicochemical parameters in the wet season, whereas electrical conductivity and total dissolved solids were seen in the dry season. The average values of the metals in the human risk assessment for carcinogenicity were As > Cd > Pb > Cr > Ni > Co, with As above the recommended threshold in several locations. However, all of the metal hazard indices were < 1, indicating that the waters were suitable for domestic purposes. Nonetheless, the relevant authorities should mandate that pharmaceutical effluents be treated before being released into bodies of water.

Utilizing triethylenetetramine-functionalized MIP-206 for highly efficient removal of Pb(II) from wastewater

The global concern over heavy metal pollution necessitates urgent measures to safeguard human health and the environment. This study focuses on employing triethylenetetramine (TETA)-functionalized MIP-206-OH (TMIP-206) as an effective adsorbent for removing Pb(II) from wastewater. TMIP-206 was synthesized via a hydrothermal method followed by functionalization with TETA. Kinetic studies demonstrate that lead removal on TMIP-206 conforms to the pseudo-second-order model, indicating an efficient removal process. Experimental results reveal that TMIP-206 aligns with the Langmuir isotherm, exhibiting a maximum removal capacity of 267.15 mg/g for lead ions. The sorption efficiency of TMIP-206 for Pb ions remains stable across six cycles, with a reduction of less than 15%. Optimal adsorption performance is observed at a pH of 6. These findings underscore the potential of TMIP-206 as an alternative for adsorbing Pb(II) from aqueous environments, addressing the global challenge of heavy metal pollution. Future research should explore the scalability and long-term stability of TMIP-206-based adsorbents to enhance their practical applicability in diverse environmental contexts and contribute to broader strategies for mitigating heavy metal contamination.

From wastewater to clean water: Recent advances on the removal of metronidazole, ciprofloxacin, and sulfamethoxazole antibiotics from water through adsorption and advanced oxidation processes (AOPs)

Antibiotics released into water sources pose significant risks to both human health and the environment. This comprehensive review meticulously examines the ecotoxicological impacts of three prevalent antibiotics-ciprofloxacin, metronidazole, and sulfamethoxazole-on the ecosystems. Within this framework, our primary focus revolves around the key remediation technologies: adsorption and advanced oxidation processes (AOPs). In this context, an array of adsorbents is explored, spanning diverse classes such as biomass-derived biosorbents, graphene-based adsorbents, MXene-based adsorbents, silica gels, carbon nanotubes, carbon-based adsorbents, metal-organic frameworks (MOFs), carbon nanofibers, biochar, metal oxides, and nanocomposites. On the flip side, the review meticulously examines the main AOPs widely employed in water treatment. This includes a thorough analysis of ozonation (O3), the photo-Fenton process, UV/hydrogen peroxide (UV/H2O2), TiO2 photocatalysis, ozone/UV (O3/UV), radiation-induced AOPs, and sonolysis. Furthermore, the review provides in-depth insights into equilibrium isotherm and kinetic models as well as prospects and challenges inherent in these cutting-edge processes. By doing so, this review aims to empower readers with a profound understanding, enabling them to determine research gaps and pioneer innovative treatment methodologies for water contaminated with antibiotics.

A solid-state pulse power sub-nanosecond SiC DSRD-based generator with high-voltage and high repetition frequency for pulse discharge water treatment

Water treatment is one of the most important issues for all walks of life around the world. The unique advantages of the solid-state power electronic pulses in water treatment make it attractive and promising in practical applications. The output voltage, rising time, repetition rate, and peak power of output pulses have a significant impact on the effectiveness of water treatment. Especially in pulse electric field treatment and pulse discharge treatment, the pulse with fast rising time achieves the advantage of generating plasma without corona, which can avoid water heating effect and greatly improve the efficiency of the pulse generator. High repetition rate can significantly reduce the peak power requirement of the pulse in water treatment application, making the equipment smaller and improving the power density. Therefore, the study developed a high-voltage high frequency sub-nanosecond pulse power generator (PPG) system for wastewater treatment. It adopts SiC DSRD (Drift Step Recovery Diode) solid-state switches and realize modular design, which can achieve high performance and can be flexible expanded according to the requirements of water treatment capacity. Finally, an expandable high-voltage PPG for water treatment is built. The output parameters of the PPG include output pulse voltage range from 1 to 5.28 kV, rise time <600 ps (20%-90%), repetition up to 1 MHz. The experiment results of PPG application for pulse discharge water treatment is presented. The results indicate that the proposed generator achieves high-efficiency degradation of 4-Chlorophenol (4-CP), which is one of the most common chlorophenol compounds in wastewater. From experiment, the homemade system can degrade 450 mL waste water containing 500 mg/L 4-CP in 35 min, with a degradation rate of 98%. Thereby, the requirement for electric field intensity decreased. Through the further quantitative analysis, the impact of frequency, voltage, and electrode spacing on the degradation effect of 4-CP is confirmed.

Application and development of foam extraction technology in wastewater treatment: A review

With the advancement of technology, wastewater treatment has become a significant challenge limiting the clean and sustainable development of chemical and metallurgical industries. Foam extraction, based on interfacial separation and mineral flotation, has garnered considerable attention as a wastewater treatment technology due to its unique physicochemical properties. Although considerable excellent accomplishments were reported, there still lacks a comprehensive summary of process features and contaminant removal mechanisms via foam extraction. According to the latest research progresses, the principles and characteristics of foam extraction technology, the classification and application of flotation reagents are systematically summarized in this work. Then comprehensively commented on the application fields and prospects of iterative flotation technology such as ion flotation, adsorption flotation and floating-extraction. The shortcomings and limitations of the current foam extraction technologies were discussed, and the feasible process intensification techniques were highlighted. This review aims to enchance the understanding of the foam extraction mechanism, and provides guidance for the selection appropriate reagents and foam extraction technologies in wastewater treatment.

Innovations in metal-organic frameworks (MOFs): Pioneering adsorption approaches for persistent organic pollutant (POP) removal

Adsorption is a promising way to remove persistent organic pollutants (POPs), a major environmental issue. With their high porosity and vast surface areas, MOFs are suited for POP removal due to their excellent adsorption capabilities. This review addresses the intricate principles of MOF-mediated adsorption and helps to future attempts to mitigate organic water pollution. This review examines the complicated concepts of MOF-mediated adsorption, including MOF synthesis methodologies, adsorption mechanisms, and material tunability and adaptability. MOFs' ability to adsorb POPs via electrostatic forces, acid-base interactions, hydrogen bonds, and pi-pi interactions is elaborated. This review demonstrates its versatility in eliminating many types of contaminants. Functionalizing, adding metal nanoparticles, or changing MOFs after they are created can improve their performance and remove contaminants. This paper also discusses MOF-based pollutant removal issues and future prospects, including adsorption capacity, selectivity, scale-up for practical application, stability, and recovery. These obstacles can be overcome by rationally designing MOFs, developing composite materials, and improving material production and characterization. Overall, MOF technology research and innovation hold considerable promise for environmental pollution solutions and sustainable remediation. Desorption and regeneration in MOFs are also included in the review, along with methods for improving pollutant removal efficiency and sustainability. Case studies of effective MOF regeneration and scaling up for practical deployment are discussed, along with future ideas for addressing these hurdles.

Ecological patterns of phytoplankton across lake cross-section: insights into co-evolution of physicochemical conditions in Chashma Lake on Indus River

Physicochemical properties of water influence planktonic diversity and distribution, which is essential in obtaining basic knowledge of aquatic biodiversity. Thus current study aims to investigate the spatiotemporal diversity, abundance ratio, and distribution of phytoplankton species and their association with water quality parameters of Chashma Lake, Pakistan. During the study period from 2018 to 2019, we measured 13 physicochemical parameters across three selected sampling sites (S1, S2, and S3) in Chashma Lake, revealing both spatial and temporal variability. Dissolved oxygen (DO) was higher in S3, while S1 exhibited higher alkalinity levels, carbon dioxide, phosphorus, and chloride levels. The study identified 77 phytoplankton species grouped into five taxonomic categories, with Cyanobacteria dominating (39.90%), followed by Chlorophyta (33.4%) and Bacillariophyta (24.88%). Euglenozoa and Ochrophyta were less abundant (1.3% and 0.41%, respectively). Spatial variations in phytoplankton distribution were noted, with Chlorophyta being more abundant at S2, Bacillariophyta and Cyanobacteria at S1, and Euglenozoa dominating at S3. Canonical Correspondence Analysis (CCA) revealed the influence of various physicochemical parameters on phytoplankton distribution. This comprehensive study provides valuable insights for the ecological assessment and monitoring of water bodies. It is recommended that continuous monitoring is required to capture long-term trends, further explore the specific environmental drivers impacting phytoplankton dynamics, and consider management strategies for maintaining water quality and biodiversity in Chashma Lake.

Innovations and challenges in adsorption-based wastewater remediation: A comprehensive review

Water contamination is an escalating emergency confronting communities worldwide. While traditional adsorbents have laid the groundwork for effective water purification, their selectivity, capacity, and sustainability limitations have driven the search for more advanced solutions. Despite many technological advancements, economic, environmental, and regulatory hurdles challenge the practical application of advanced adsorption techniques in large-scale water treatment. Integrating nanotechnology, advanced material fabrication techniques, and data-driven design enabled by artificial intelligence (AI) and machine learning (ML) have led to a new generation of optimized, high-performance adsorbents. These advanced materials leverage properties like high surface area, tailored pore structures, and functionalized surfaces to capture diverse water contaminants efficiently. With a focus on sustainability and effectiveness, this review highlights the transformative potential of these advanced materials in setting new benchmarks for water purification technologies. This article delivers an in-depth exploration of the current landscape and future directions of adsorbent technology for water remediation, advocating for a multidisciplinary approach to overcome existing barriers in large-scale water treatment applications.

Spatial analysis of leachate penetration at Lemna dumpsite, Calabar: Implications for sustainable waste management in Cross River State

This study rigorously investigated the spatial analysis of leachate penetration at Lemna dumpsite, located in Calabar, Cross River State, Nigeria. Purposeful soil sampling, performed at specific intervals (5 m, 25 m, and 50 m) along the Electrical Resistivity profile line within the dumpsite, was augmented by water sample collection from five boreholes near Lemna dumpsite. Utilizing Electrical Resistivity Tomography (ERT) and Vertical Electric Sounding (VES) survey techniques, resistivity data were systematically gathered to comprehensively analyze the Leachate Penetration in the Lemna dumpsite. Laboratory analysis of soil and borehole water quality focused on Benzene, Toluene, Ethylbenzene, and Xylene (BTEX), with paired sample t-tests applied for statistical scrutiny. Analyzing the ERT and VES data employed sophisticated techniques embedded in Resistivity Two Dimension Invasion software and Advanced Geosciences Incorporation Earth Imager software. Substantial disparities (p < 0.05) emerged in the paired sample t-tests for BTEX in soil compared to National Environmental Standard Regulation and Enforcement Agency (NESREA) limits. Similarly, BTEX in borehole water displayed significant differences (p < 0.05) when compared to World Health Organization (WHO) standards, raising alarming concerns about the safety and portability of groundwater in the area. The examination of dumpsite leachate penetration revealed a resistivity anomaly of 8.01 Ωm and an inverse depth of 12.4 m, underscoring profound environmental implications and necessitating immediate remediation efforts. Additionally, Vulnerability and Aquifer Protective Capacity Index (VES) results, with a rating of <0.1, indicated severely compromised aquifer protective capacity, emphasizing the vulnerability of groundwater resources to further contamination. Our study advocates for strategic management, remediation, and monitoring measures to prevent contamination and safeguard water quality in the region.

Evaluation of irrigation, drinking, and risk indices for water quality parameters of alpine lakes

Alpine lakes are aquatic ecosystems that maintain and regulate water supply for the downstream streams, rivers, and other reservoirs. This study examined the water characteristics of various alpine lakes in Gilgit-Baltistan, Northern Pakistan. For this purpose, water was sampled and investigated for basic parameters, anions, and cations using the multi-parameter analyzers and atomic absorption spectrophotometer. Physicochemical parameters of alpine lakes were noted under the World Health Organization water guidelines, except for fluoride (F-) and turbidity in 4.3% and 36% of samples, respectively. Water quality index (WQI) classified samples (93%) as excellent and good quality (7%). Results showed maximum chronic daily intake values (0.14 ± 0.01 mg/kg-day) for nitrate (NO3-) and hazard quotient (0.80 ± 0.24) for F- in children via water intake from Upper Kachura and Shausar Lakes, respectively. Statistical analyses of Piper and Gibbs's plots revealed that the water quality is mainly characterized by bedrock geology.

Human viral pathogens in the wastewater-source water-drinking water continuum: Evidence, health risks, and lessons for future outbreaks in low-income settings

Human viral pathogens, including SARS-CoV-2 continue to attract public and research attention due to their disruption of society, global health, and the economy. Several earlier reviews have investigated the occurrence and fate of SARS-CoV-2 in wastewater, and the potential to use such data in wastewater-based epidemiology. However, comprehensive reviews tracking SARS-CoV-2 and other viral pathogens in the wastewater-water-drinking water continuum and the associated risk assessment are still lacking. Therefore, to address this gap, the present paper makes the following contributions: (1) critically examines the early empirical results to highlight the occurrence and stability of SARS-CoV-2 in the wastewater-source water-drinking water continuum, (2) discusses the anthropogenic and hydro(geo)logical processes controlling the circulation of SARS-CoV-2 in the wastewater-source water-drinking water continuum, (3) discusses the risky behaviour, drivers and high-risk settings in the wastewater-source water-drinking water continuum, (4) uses the available empirical data on SARS-CoV-2 occurrence in the wastewater-source water-drinking water continuum to discuss human health risks from multiple exposure pathways, gendered aspects of SARS-CoV-2 transmission via shared on-site sanitation systems, and (5) develops and risk mitigation strategy based on the available empirical evidence and quantitative human risk assessment data. Finally, it presents a comprehensive research agenda on SARS-CoV-2/COVID-19 to guide the mitigation of future similar outbreaks in low-income settings.

Health risk assessment of heavy metals in saffron (Crocus sativus L.) cultivated in domestic wastewater and lake water irrigated soils

Irrigation of crops with domestic wastewater (DW) is a common practice in developing countries like India. However, domestic wastewater irrigation poses a risk of migration of toxic heavy metals to edible parts of crops, which requires serious measures to prevent their uptake. In this study, the effect of DW irrigation in comparison with Sarbal Lake water (SLW) and borewell water (BW) on soil characteristics and cultivated saffron (Crocus sativus L.) was investigated. For this purpose, samples of water, soil, and saffron (corm, petal, and stigma) were collected from the suburban area of Pampore, Srinagar district, Jammu and Kashmir, India. The results showed that DW irrigation had the maximum significant (p < 0.05) influence on the physico-chemical and nutrient characteristics of the soil, followed by SLW and BW irrigation, respectively. The growth and yield parameters of saffron were also significantly (p < 0.05) increased in the case of DW irrigation as compared to SLW and BW. The quality ranking of the cultivated saffron was found to be in accordance with the ISO standard (III: BW and II: DW and SLW). On the other hand, DW irrigation showed a significant increase in heavy metal contents (mg/kg) of saffron plant parts such as As (0.21-0.40), Cd (0.04-0.09), Cr (0.16-0.41), Cu (7.31-14. 75), Fe (142.38-303.15), Pb (0.18-0.31), Mn (15.26-22.81), Hg (0.18-0.25), Ni (0.74-1.18), Se (0.13-0.22), and Zn (3.44-4.59), followed by SLW and BW. However, the levels of heavy metals did not exceed the FAO/WHO safe limits. Bioaccumulation factor (BAF), dietary intake modeling (DIM<0.006496), health risk assessment (HRI<0.028571), and target hazard quotient (THQ<1) analyses showed no potential health hazard associated with the consumption of saffron irrigated with DW and SLW. Therefore, the results of this study provide valuable insights into the optimization of irrigation sources for saffron cultivation.