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Due to its geographical location in the arid and semi-arid zone, Algeria is suffering from water stress amplified by the effects of climate change. For these reasons this study was conducted to evaluate the suitability for agricultural reuse of treated wastewater of Baraki WWTP. The quality for agricultural reuse is related to the physicochemical parameters and indicators of water quality. The bacteriological characteristics including total and fecal coliforms, fecal enterococci, Salmonella spp. and Staphylococcus spp. were also considered. The results revealed that SAR and SSP values were excellent for irrigation. A Wilcox diagram showed that most of the samples fell in the field of C3-S1 indicating high salinity and low sodium water. The physicochemical results indicated that most of parameters are in conformity with standards except ammonia NH4+ and total nitrogen that are higher than the permissible limit of USEPA and FAO. The average concentrations of heavy metals are low compared with the FAO recommendations. However, the bacteriological analyses confirmed the existence of germs indicating a fecal contamination exceeding the WHO regulations but an absence of pathogenic germs. Hence, the disinfection of this water and an adequate treatment is needed before its use for agricultural purposes. HIGHLIGHTS Algeria is actually facing a water crisis, especially in the agricultural sector.; Reusing treated wastewater is an alternative for irrigation.; WWTP of Baraki which uses sand filtration is a good choice for study.; The physico-chemical and bacteriological quality of the treated wastewater is poor.; Disinfection treatment is necessary for the reuse of this treated wastewater.;

This study focuses on the probable use of carbonized char prepared from PET plastic bottles for heavy metals (HMs) adsorption (Cd2+, Pb2+, Cu2+, and Zn2+). The prepared adsorbent is characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR). Batch adsorption experiments were conducted with the influencing of different operational conditions: contact time (1–180 min), adsorbate concentration (25–300 mg/L), adsorbent dose (0.5–6 g/L), pH (3–7), and temperature (25–60 ºC). High coefficient value [Cd2+ (R2 = 0.99), Pb2+ (R2 = 0.97), Cu2+ (R2 = 0.94), and Zn2+ (R2 = 0.98)] of process optimization model suggest that this model was significant, where pH and adsorbent dose expressively stimulus removal efficiency including 86.68, 73.66, 67.10, and 57.04% for Cd2+, Pb2+, Cu2+, and Zn2+ at pH (7), respectively. Furthermore, ANN and BB-RSM revealed a good association between the tested and projected values. The maximum monolayer adsorption capacity of Cd2+, Pb2+, Cu2+, and Zn2+ was 263.157, 78.740, 196.078, and 84.745 mg/g, respectively. Pseudo-second-order was the well-suited kinetics, where Langmuir and Freundlich isotherm could explain better for equilibrium adsorption data. Thermodynamic study shows HMs adsorption is favorable, exothermic, and spontaneous. HIGHLIGHTS Carbonized adsorbent was prepared from PET bottle waste by a simple thermal dissociation method.; Response surface methodology and artificial neural network express a strong correlation between the experimental and projected heavy metal removal efficiency.; Carbonized adsorbents reveal satisfactory results for experimental (Cd = 86.68%, Pb = 73.66%, Cu = 67.10%, and Zn = 57.04%) and real wastewater applications (Cd = 99.2%, Pb = 62.20%, Cu = 97.63%, and Zn = 64.47%).;

The aim of this study was to investigate the use of wastewater-based epidemiology (WBE) to estimate heavy metal exposure in Sungai Petani, Malaysia. Atomic absorption spectroscopy was used to detect copper (Cu), nickel (Ni), zinc (Zn), iron (Fe), and cadmium (Cd) in wastewater from eight sewage treatment facilities in Sungai Petani in January 2022. The heavy metal concentrations were measured in both influent and effluent, and the mean concentrations in the wastewater were found to be in the following order: Fe > Ni > Zn > Cd > Cu, with a 100% detection frequency. The results of WBE estimation showed that Fe, Ni, and Zn had the highest estimated per population exposure levels, while Cd had the lowest. Compared to a similar study conducted in Penang, Malaysia, all metals except Cu were found to have higher concentrations in Sungai Petani, even though it is a non-industrial district. These findings highlight the importance of addressing heavy metal contamination in Sungai Petani and implementing effective risk management and prevention strategies. HIGHLIGHTS A new study has found that Sungai Petani, Malaysia, has high levels of heavy metals in its wastewater.; The study's findings are concerning, as heavy metals can have serious health consequences.; Researchers urge the government to take steps to reduce heavy metal pollution in the area.;

Health authorities are particularly concerned about water security in Enugu, southeast Nigeria and heavy metal (HM) pollution. The HM profiles of 51 samples collected from 17 different commercial bottled water brands in Enugu were examined using an flame atomic absorption spectroscopy. Cd, Cr, Cu, Pb, Ni, and Zn had mean values of 0.15 ± 0.03, 0.03 ± 0.02, 0.16 ± 0.03, 0.13 ± 0.02, and 0.02 ± 0.01 mg/L, respectively. The highest levels of Pb2+ were 0.27 mg/L in Exalté, Ni2+ 0.26 mg/L in Jasmine, Cd2+ 0.36 mg/L in Ezbon, Cr3+ 0.07 mg/L in Trinity, Cu2+ 0.04 mg/L in Bigi, and Zn2+ 0.02 mg/L in Aquarapha. The amounts of Cr, Cu, and Zn were below the allowable limits; nevertheless, the Pb content in eight bottled water samples exceeded both the Nigerian and World Health Organization (WHO)/U.S. Environmental Protection Agency (USEPA) permissible limits. The Cd2+ and Ni2+ levels in the 11th and 4th bottled water samples were above the WHO/USEPA-approved limits. Statistical evaluation revealed significant differences in the amounts of HM ions in the samples (p < 0.05). The findings indicated that concentration levels of Cd2+ Ni2+, and Pb2+ pose a public health concern that needs to be addressed due to potential risk to consumer health. HIGHLIGHTS Pb detected in the remaining nine samples and exceeded the allowable limits set by the World Health Organization (WHO) and U.S. Environmental Protection Agency (USEPA).; Cd2+ was found in 11 bottled water samples, all of which were above the WHO and USEPA acceptable limits.; The result (dendrogram) showed five clusters, with Cu being more related to Zn than to Pd, Ni, Cd, and Cr.; The use of nanofiltration and microfiltration is known to remove hexavalent chromium (Cr(VI)).;

Worldwide, the harmful ion contamination of water has become a serious problem because of unregulated industry, energy production, and mining, which greatly increase the concentration of pollutants in water. The novel membranes through adsorbent self-assembly, such as protein amyloids, were explored for wastewater treatment. Herein, we report amyloid fibril (AF)-embedded bacterial cellulose nanohybrid membrane for efficient removal of heavy metal from industrial effluent. AFs are synthesized by heat treatment using bovine serum albumin and embedded with bacterial cellulose nanomembrane (BCN). The AF-embedded BCN (AF/BCN) was characterized using microscopy and spectroscopic methods. In addition, the well-ordered multi-layered AF/BCN filtration assembly was fabricated in the commercial cartridge and validated for the removal of heavy metals (Pb2+ and Hg2+) from wastewater and treatment of industrial wastewater sample containing heavy metals. Our multi-layered filtration assembly removed Hg2+ and Pb2+ with efficiency of 95 and 78.34%, respectively. A computational study using molecular docking has also been performed for the identification of metal entrapment sites. Moreover, our AF/BCN filtration assembly showed high regeneration capacity up to four cycles. The isotherm model also revealed a strong fit and good adsorption behaviour. This makes potential filtration assembly for low-cost, high-efficiency for the removal of heavy metal from wastewater. HIGHLIGHTS Computational approaches methods for the study of bovine serum albumin.; Synthesis of amyloid fibril, amyloid-embedded bacterial cellulose nanomembrane (BCN), and fabrication of amyloid-embedded BCN filtration assembly.; Heavy metal removal analysis from industrial wastewater.;

This study takes Guanshan River Basin, a typical inflow river of the Danjiangkou Reservoir, as the research area, and the nonpoint source (NPS) pollution characteristics of nitrogen and phosphorus from 2013 to 2018 were evaluated by establishing a Soil and Water Assessment Tool (SWAT) model. The pollution characteristics of heavy metals were also evaluated by combining the SWAT and simple output coefficient method. The results show that the pollutant load in Guanshan River Basin contributes significantly to the Danjiangkou Reservoir. Temporally, pollutant loads were primarily concentrated in the flood season, which had a significant positive correlation with precipitation, water yield, and sediments in the abundant period. Among them, sediments were the most important driving factor, followed by water yield. Spatially, pollutant loads were mainly concentrated downstream of the basin, where cultivated land is widespread. In this regard, it is suggested that the input of chemical fertilizers, pesticides, and livestock manure in cultivated land should be controlled and soil erosion downstream of the basin should be prevented to mitigate nitrogen, phosphorus, and heavy metal pollution. This research offers a basis for the formulation and implementation of watershed management for the Danjiangkou Reservoir. HIGHLIGHTS Based on the Soil and Water Assessment Tool model, the nonpoint source (NPS) pollution features and sources of nitrogen, phosphorus, and heavy metals were analyzed and discussed.; The NPS pollution is mainly concentrated in the flood season, and sediment is the most important driving factor, followed by water yield.; The input of fertilizers and pesticides into cultivated land should be controlled, and soil erosion should be prevented in the study's high-load area.;

Electroplating wastewater contains heavy metal ions and organic matter. These contaminants not only endanger the environment but also pose risks to human health. Despite the development of various treatment processes such as chemical precipitation MBR, electrocoagulation (EC) ceramic membrane (CM), coagulation ultrafiltration (UF) reverse osmosis (RO), and CM RO. These methods are only effective for low concentrations of heavy metals and struggle with high concentrations. To address the challenge of treating electroplating wastewater with high heavy metal content, this study focuses on the wastewater from Dongfang Aviation Machinery Processing Plant. It introduces an EC and integrated membrane (IM) treatment process for electroplating wastewater. The IM comprises microfiltration (MF) membrane, nanofiltration (NF) membrane, and RO membrane. Results indicated that under specific conditions, such as a pH of 8, current density of 5 A/dm2, electrode plate spacing of 2 cm, 35 min of electrolysis time, and influent pH of 10 for the IM, removal rates of Zn2+, Cu2+, Ni2+, and TCr in the wastewater exceeded 99%. The removal rates of chemical oxygen demand (COD), suspended solids (SS), total phosphorus (TP), total nitrogen (TN), and petroleum in wastewater exceed 97%. Following a continuous cleaning process, the membrane flux can consistently recover to over 94.3%. HIGHLIGHTS Comprehensive treatment of wastewater pollution.; Application of environmental protection and energy conservation technology.; Efficient removal of harmful substances.; Systematic wastewater treatment solution.; Effectively removing heavy metals.;

This study investigates groundwater contamination by arsenic and iron and its health implications within the Sylhet district in Bangladesh. Utilizing geographic information system (GIS) and inverse distance weighting (IDW) methods, hazard maps have been developed to evaluate contamination risk across various upazilas. The findings show significant arsenic and iron pollution, particularly in the northwestern part of the district. In about 50% of the area, especially in Jaintiapur, Zakiganj, Companiganj, and Kanaighat where arsenic levels surpass 0.05 mg/L which is the standard limit of Bangladesh. Iron levels peak at 13.83 mg/L, severely impacting 45% of the region, especially in Gowainghat, northeastern Jaintiapur, Zakigonj, and Golabganj. The study employs USEPA health risk assessment methods to calculate the hazard quotient (HQ) and hazard index (HI) for both elements via oral and dermal exposure. Results indicate that children face greater noncarcinogenic and carcinogenic risks than adults, with oral HI showing significant risk in Balagonj and Bishwanath. Dermal adsorption pathways exhibit comparatively lower risks. Cancer risk assessments demonstrate high carcinogenic risks from oral arsenic intake in all areas. This comprehensive analysis highlights the urgent need for effective groundwater management and policy interventions in the Sylhet district to mitigate these health risks and ensure safe drinking water. HIGHLIGHTS Arsenic levels exceed 0.05 mg/L in 50% of Sylhet, posing severe health risks.; 45% of the area suffers from iron contamination (1.01–13.83 mg/L).; Children in Balagonj and Bishwanath upazilas are exposed to high health risks.; Carcinogenic risks from arsenic are high, especially orally.; Combined arsenic and iron levels in some areas are 2.74–4.75 mg/L, indicating severe contamination.;

This study investigates the heavy metals (HMs) and other constituents in Lake Tana around the Gulf of Bahir Dar City. The water sample was collected from areas receiving drainage water and a reference sample was collected from areas away from the urban impact, both during dry and wet seasons. Pollution sources and levels were determined using pollution indices and GIS spatial analyses. All in situ parameters were in the recommended range of the USEPA aquatic and WHO drinking water guidelines. The level of dissolved P was recorded between 0.03 and 0.9 mg/l and the level of N-NO3 ranged from 0.05 to 1.01 mg/l indicating that the limits were above USEPA aquatic criteria. The HMs varied from 0.08 to 2.85 mg/l for Cu, 0.10 to 1.60 mg/l for Fe, 0.04 to 0.22 mg/l for Cr, and Mn was below detection. Cr and Fe were above the aquatic and drinking water guideline limit. Spatially, pollution was more significant in areas receiving drainage. Also, except Cu and Fe, other parameters were higher in the rainy season indicating storm runoff pollution. The overall pollution indices of water quality status, such as water quality index 63, heavy metal pollution index 3.1, and nutrient pollution index 4.7, indicated the quality level of water to be alarming. Therefore, comprehensive regulatory and waste management practices are needed. HIGHLIGHTS This research is a first study evaluating the heavy metals (HMs) in Lake Tana.; Both HMs (Cr and Fe) and nutrients (N and P) exceeded the aquatic limit.; GIS spatial analysis shows that concentration is at a high level in urban drainage discharge area.; HMs and nutrients are at high levels in the rainy season.; The calculated pollution indices such as WQI, HPI, and NPI indicated the water quality of the lake to be alarming.;

The aim of this study was to investigate the use of wastewater-based epidemiology (WBE) to estimate heavy metal exposure in Sungai Petani, Malaysia. Atomic absorption spectroscopy was used to detect copper (Cu), nickel (Ni), zinc (Zn), iron (Fe), and cadmium (Cd) in wastewater from eight sewage treatment facilities in Sungai Petani in January 2022. The heavy metal concentrations were measured in both influent and effluent, and the mean concentrations in the wastewater were found to be in the following order: Fe > Ni > Zn > Cd > Cu, with a 100% detection frequency. The results of WBE estimation showed that Fe, Ni, and Zn had the highest estimated per population exposure levels, while Cd had the lowest. Compared to a similar study conducted in Penang, Malaysia, all metals except Cu were found to have higher concentrations in Sungai Petani, even though it is a non-industrial district. These findings highlight the importance of addressing heavy metal contamination in Sungai Petani and implementing effective risk management and prevention strategies. [ABSTRACT FROM AUTHOR]

Health authorities are particularly concerned about water security in Enugu, southeast Nigeria and heavy metal (HM) pollution. The HM profiles of 51 samples collected from 17 different commercial bottled water brands in Enugu were examined using an flame atomic absorption spectroscopy. Cd, Cr, Cu, Pb, Ni, and Zn had mean values of 0.15+0.03, 0.03+0.02, 0.16+0.03, 0.13+0.02, and 0.02+0.01 mg/L, respectively. The highest levels of Pb2+ were 0.27 mg/L in Exalté, Ni2+ 0.26 mg/L in Jasmine, Cd2+ 0.36 mg/L in Ezbon, Cr3+ 0.07 mg/L in Trinity, Cu2+ 0.04 mg/L in Bigi, and Zn2+ 0.02 mg/L in Aquarapha. The amounts of Cr, Cu, and Zn were below the allowable limits; nevertheless, the Pb content in eight bottled water samples exceeded both the Nigerian and World Health Organization (WHO)/U.S. Environmental Protection Agency (USEPA) permissible limits. The Cd2+ and Ni2+ levels in the 11th and 4th bottled water samples were above the WHO/USEPAapproved limits. Statistical evaluation revealed significant differences in the amounts of HM ions in the samples (p,0.05). The findings indicated that concentration levels of Cd2+ Ni2+, and Pb2+ pose a public health concern that needs to be addressed due to potential risk to consumer health. [ABSTRACT FROM AUTHOR]

This study investigates groundwater contamination by arsenic and iron and its health implications within the Sylhet district in Bangladesh. Utilizing geographic information system (GIS) and inverse distance weighting (IDW) methods, hazard maps have been developed to evaluate contamination risk across various upazilas. The findings show significant arsenic and iron pollution, particularly in the northwestern part of the district. In about 50% of the area, especially in Jaintiapur, Zakiganj, Companiganj, and Kanaighat where arsenic levels surpass 0.05 mg/L which is the standard limit of Bangladesh. Iron levels peak at 13.83 mg/L, severely impacting 45% of the region, especially in Gowainghat, northeastern Jaintiapur, Zakigonj, and Golabganj. The study employs USEPA health risk assessment methods to calculate the hazard quotient (HQ) and hazard index (HI) for both elements via oral and dermal exposure. Results indicate that children face greater noncarcinogenic and carcinogenic risks than adults, with oral HI showing significant risk in Balagonj and Bishwanath. Dermal adsorption pathways exhibit comparatively lower risks. Cancer risk assessments demonstrate high carcinogenic risks from oral arsenic intake in all areas. This comprehensive analysis highlights the urgent need for effective groundwater management and policy interventions in the Sylhet district to mitigate these health risks and ensure safe drinking water. [ABSTRACT FROM AUTHOR]

Mekelle is one of the Ethiopian cities suitable for urban and peri-urban agriculture for cultivating leafy vegetables using wastewater. The consumption of unprocessed and processed leafy vegetables is also very high in the city. Wastewater samples collected from four experimental sites (ESs) in Hadnet district of the city had higher concentrations in 4 (i.e., Cd, Cr, Cu, and Mn) of the 10 heavy metals tested than the permissible limit established by pertinent standards. Spring water samples collected from another site called Kallamino, designated as a comparison site, also had higher concentrations in 4 (i.e., Al, As, Cd, and Cu) of the 10 heavy metals tested. However, the leafy vegetables grown in the least contaminated ES had higher concentrations in 6-7 of the 10 heavy metals tested. The lettuce and spinach samples had elevated concentrations of As and Al, respectively. The wastewater used to irrigate vegetable farms in Hadnet district is not safe enough. More importantly, the soils of the farms might have accumulated far more heavy metals. The cultivated lettuce, spinach, and cauliflower are highly contaminated. Thus, the use of wastewater for irrigating urban and peri-urban farms needs to be regulated. HIGHLIGHTS Tests of wastewaters used in urban agriculture for heavy metal contents.; Tests of three leafy vegetables irrigated with wastewater for heavy metal contents.; Contamination of the three leafy vegetables with high level of 6 to 7 heavy metals tested.;

Groundwater contamination due to the leaching of harmful pollutants such as heavy metals, xenobiotic compounds, and other inorganic compounds from solid waste dumping sites has become a major health concern in recent times. Therefore, to assess the effects of the Bandhwari landfill site, groundwater samples from the surrounding region of the dumping site were collected and analyzed for heavy metals and physicochemical properties. The total dissolved solids (TDS) of 67% of samples exceeded the Bureau of Indian Standards (BIS) permissible limits which makes it unfit for drinking purposes. The groundwater samples were also analyzed for iron (Fe), lead (Pb), zinc (Zn), nickel (Ni), copper (Cu), cadmium (Cd), and chromium (Cr) concentrations and results of heavy metal concentration in the groundwater around the Bandhwari landfill follow the concentration trend of Pb > Cd > Ni > Cu > Zn > Fe > Cr. Risk assessment of consumers' health was done using target hazard quotient calculations which were less than unity (threshold value of

Combining with the characteristics of Fe3O4 and activated carbon, magnetic granular activated carbon (GAC–Fe3O4) was prepared by chemical coprecipitation. With GAC–Fe3O4 as the adsorbent, the effects of GAC–Fe3O4 dosage, the initial pH of wastewater temperature, and the initial concentration of copper (II) and chromium (Ⅵ) on the removal performance were explored. The adsorption process of copper (II) and chromium (VI) on magnetic GAC was studied using adsorption kinetics, adsorption isotherms, scanning electron microscopy, and infrared spectroscopy. The experimental results indicate that among these influencing factors, the pH value of wastewater plays a vital role in the removal efficiency. When the pH value was 6 and 2, the initial concentration of copper (II) and chromium (VI) ions was 5 ppm, the optimum removal efficiencies of copper (II) and chromium (VI) were 99.98 and 96.39%, respectively. As to the adsorption mechanism of GAC–Fe3O4, the adsorption of copper (II) and chromium (VI) in wastewater was more consistent with the Langmuir model. The adsorption process in this study can be well explained by the pseudo-second-order kinetic model. HIGHLIGHTS The preparation of a magnetically activated carbon particles loaded with ferric oxide.; Magnetic granular activated carbon (GAC) has good recoverability.; Magnetic GAC has a good treatment effect on wastewater containing copper (II) and chromium (VI).;

Groundwater contamination due to the leaching of harmful pollutants such as heavy metals, xenobiotic compounds, and other inorganic compounds from solid waste dumping sites has become a major health concern in recent times. Therefore, to assess the effects of the Bandhwari landfill site, groundwater samples from the surrounding region of the dumping site were collected and analyzed for heavy metals and physicochemical properties. The total dissolved solids (TDS) of 67% of samples exceeded the Bureau of Indian Standards (BIS) permissible limits which makes it unfit for drinking purposes. The groundwater samples were also analyzed for iron (Fe), lead (Pb), zinc (Zn), nickel (Ni), copper (Cu), cadmium (Cd), and chromium (Cr) concentrations and results of heavy metal concentration in the groundwater around the Bandhwari landfill follow the concentration trend of Pb.Cd.Ni.Cu.Zn.Fe.Cr. Risk assessment of consumers' health was done using target hazard quotient calculations which were less than unity (threshold value of ,1), indicating that heavy metal concentrations do not pose any serious health effect according to total hazard quotient values. The results of the study made it evident that groundwater is not suitable for drinking purposes due to excess values of water quality parameters but poses no risk due to studied metal concentrations. [ABSTRACT FROM AUTHOR]

The ability of a composite adsorbent composed primarily of various waste materials to adsorb heavy metals, NH3-N, and chemical oxygen demand (COD) from landfill leachate was investigated through batch sorption experiments. The study determined the optimal contact time and adsorbent dosage for the removal of Pb, Zn, Cu, Fe, NH3-N, and COD to be 15, 90, 30, 180, 30, and 30 min, respectively. The corresponding optimum adsorbent dosages were determined to be 5, 30, 5, 15, 5, and 30 g, respectively. The composite adsorbent exhibited high removal efficiencies, achieving the following maximum values: 96.4% for Pb, 92.7% for Zn, 60.3% for Cu, 87.1% for Fe, 75.0% for NH3-N, and 67.5% for COD. Pb and Fe showed the best fit with a Langmuir isotherm model, with corresponding adsorption capacities of 0.0165 and 1.14 mg/g, respectively. For Zn, Cu, NH3-N, and COD, the equilibrium data demonstrated the best fit with an Elovich isotherm model, with adsorption capacities of 0.004, 0.005, 0.016, and 4.29 mg/g, respectively. The kinetic data followed the pseudo-second-order kinetic model. It presented a potential solution for the disposal of the waste from which it was derived. HIGHLIGHTS This investigates the applicability of a composite adsorbent made of low-cost/waste materials, in landfill leachate treatment.; The composite adsorbent has considerable treatment potential.; This can be an initial study leading to further studies.; The use of waste materials makes treatment economically and practically feasible.; This is also a sustainable reuse application for the waste to be dumped.;

The aim of the study was to assess water quality in the Saveh aquifer for drinking, public health, and agricultural uses. The heavy metal pollution index (HPI), hazard index (HI) using non-carcinogenic health risk assessment, sodium percentage, sodium adsorption ratio (SAR), irrigation water quality index (IWQI), and a Piper diagram were used. The HPI exceeded 3,300, much higher than the WHO critical value, which is 100. The aquifer is severely contaminated with heavy metals and unsuitable for drinking. The heavy metal concentrations also caused the water to have cumulative HI > 1 in 54 and 77% of sampling wells, respectively, for adults and children. For agriculture, both %NA and IWQI were stricter than SAR. Most of the aquifer was deemed suitable for irrigation using SAR, while %Na showed most parts unreliable, and IWQI represented almost all areas unsuitable for irrigation. The Piper diagram showed that the dominant water type was N–Cl, followed by Na–HCO3 and Ca–HCO3, indicating high aquifer salinity. Generally, the Saveh aquifer is saline and heavily polluted with heavy metals, so its use for drinking and/or irrigation carries many risks. HIGHLIGHTS Evaluating water quality of Saveh aquifer in Iran for drinking, public health, and agricultural purposes.; Using heavy metal pollution index, hazard index (HI), sodium percentage, sodium adsorption ratio, and irrigation water quality index (IWQI).; Children and adults are at high non-carcinogenic risk via both drinking and dermal exposure.; IWQI and %Na showed most areas of aquifer inappropriate for irrigation.;

The amount of medical waste generated has increased enormously since the COVID-19 outbreak. An incineration process is the main method that is usually used to treat this waste, causing an increase in both medical waste bottom ash (MWBA) and medical waste fly ash (MWFA). In this work, the physical and chemical characteristics of MWFA and MWBA were reviewed. This ash contains high levels of polychlorinated dibenzo-p-dioxin (PCDD), dibenzofurans (PCDFs), and heavy metals. Furthermore, medical waste ash appears to have high leachability in the toxicity characteristics leaching procedure (TCLP) test and the European standard test (EN 12457). Owing to its toxicity, medical ash can be treated using various methods prior to disposal based on the covered review. These techniques include chemical, supercritical fluid, cement-based, melting, microwave, and mechanochemical techniques. The shortcomings of some of these treatment methods have been identified, such as the emission of high levels of chlorine from the melting technique, limited applications of the flotation method on the industrial scale, long-term stability of leachate treated by cement-based methods that have not been confirmed yet, and high energy consumption in the supercritical technique. This review also covers possible applications of medical waste ash in cement production, agriculture, and road construction. HIGHLIGHTS Medical waste ash contains high concentrations of dioxins.; Heavy metals in medical waste ash have a high leachability in the soil and groundwater.; Further investigations to solve multiple problems in treatment techniques of medical waste ash are required.; Medical waste ashes have been found to be beneficial in concrete production.;

This work reports the use of Mangifera kemanga leaves (MKL) treated with ethanol and nitric acid as an adsorbent to remove Cr(VI) and Pb(II) ions at different pHs, adsorbent dosages, times, initial metal ion concentrations, and temperatures. The MKL's maximum adsorption capacity was 213 mg/g for Cr(VI) at pH 2 and 89 mg/g for Pb(II) at pH 6. Batch experiments showed that MKL follows the Langmuir isotherm model in absorbing Cr(VI) and Pb(II). The Cr(VI) and Pb(II) adsorption kinetics are best suited by the pseudo-second-order kinetics model. Thermodynamic data studies indicated that surface complexation coexisted with ion exchange as the preliminary removal means. The results implied that MKL could potentially remove Cr(VI) and Pb(II). HIGHLIGHTS Kemang leaves were used as biosorbent for Cr(VI) and Pb(II) removal from aqueous solution.; The biosorption capacity of the biosorbent for Cr(VI) was 212.76 mg/g.; The biosorption capacity of the biosorbent for Pb(II) was 89.29 mg/g.; Both Cr(VI) and Pb(II) adsorption were well suited by a pseudo-second-order model.; Biosorbent may be regenerated and reused, indicating materials’ economic benefits.;

This study describes the use of a continuous flow system for photocatalytic reactions employing a TiO2 sol–gel structured catalyst. The catalyst was immobilized on various stainless steel meshes to investigate the barium(II) removal. To verify its photocatalytic activity, batch tests were carried out and the results were compared to the commercial catalyst P25. Effects of thermal treatment on the structured catalyst were investigated. The continuous flow photocatalytic tests were conducted under different experimental conditions through an experimental design to verify the effect of the parameters (pH and volume flow). The results of the batch tests indicated that the TiO2 sol–gel catalyst showed very similar activity to the TiO2 P25 when used in powder suspension (32% reduction of Ba2+). In the continuous flow process, maximum adhesion of catalysts on meshes was found at a calcination temperature of 623 K. The experimental design indicated the pH as a significant parameter in the studied conditions. It was observed that at pH levels close to 7, also indicated by the study of the zero charge point and lower flow rates, it was possible to obtain ∼20% removal of Ba2+ ions, in a continuous flow reactor with a residence time of 83 min. HIGHLIGHTS Study for the application of photocatalytic processes for industrial decontamination.; Synthesis of sol-gel catalysts structured on stainless steel meshes.; Application of a continuous flow process to remove industrial pollutants.; Removal of barium(II) from surface waters; Effect of pH and calcination temperature on immobilized catalysts applied to barium(II) removal.;

Heavy metal pollution damages the ecosystems and presents a major problem for public health. Thus, an urgent need was developed to decrease the high levels of heavy metals in the soil and aquatic environments. With this aim, numerous physicochemical strategies were developed. However, they are money-consuming, require the use of energy and chemical additives and can release secondary compounds that can pollute and cause great damage to the environment. Then, biological methods based on the investigation of bacteria, fungi and plants along with their derived secondary active metabolites became the best alternatives. Using plant capacities, different phytoremediation strategies were developed such as phytoextraction, phytovolatilization, rhizofiltration and phytostabilization. Regarding bioremediation, bacterial biosorption of heavy metals, biolixiviation and lagooning offer great potential for their environmental cleaning. Additionally, the use of secondary active metabolites, such as biosurfactants, is well-studied. Generally, they are a class of structurally very varied molecules commonly synthesized by many microorganisms with amphiphilic character. Owing to their anionic charge, they have the capacity to sequestrate heavy metals permitting their elimination. Glycolipids and lipopeptides are among the most recognized biosurfactants with interesting heavy metal chelating properties. HIGHLIGHTS Studied heavy metal pollution and toxicology.; Bioremediation and phytoremediation technologies for heavy metal depollution.; Use of biosurfactants as heavy metal chelators.;

The ability of a composite adsorbent composed primarily of various waste materials to adsorb heavy metals, NH3-N, and chemical oxygen demand (COD) from landfill leachate was investigated through batch sorption experiments. The study determined the optimal contact time and adsorbent dosage for the removal of Pb, Zn, Cu, Fe, NH3-N, and COD to be 15, 90, 30, 180, 30, and 30 min, respectively. The corresponding optimum adsorbent dosages were determined to be 5, 30, 5, 15, 5, and 30 g, respectively. The composite adsorbent exhibited high removal efficiencies, achieving the following maximum values: 96.4% for Pb, 92.7% for Zn, 60.3% for Cu, 87.1% for Fe, 75.0% for NH3-N, and 67.5% for COD. Pb and Fe showed the best fit with a Langmuir isotherm model, with corresponding adsorption capacities of 0.0165 and 1.14 mg/g, respectively. For Zn, Cu, NH3-N, and COD, the equilibrium data demonstrated the best fit with an Elovich isotherm model, with adsorption capacities of 0.004, 0.005, 0.016, and 4.29 mg/g, respectively. The kinetic data followed the pseudo-second-order kinetic model. It presented a potential solution for the disposal of the waste from which it was derived. [ABSTRACT FROM AUTHOR]

The amount of medical waste generated has increased enormously since the COVID-19 outbreak. An incineration process is the main method that is usually used to treat this waste, causing an increase in both medical waste bottom ash (MWBA) and medical waste fly ash (MWFA). In this work, the physical and chemical characteristics of MWFA and MWBA were reviewed. This ash contains high levels of polychlorinated dibenzo-p-dioxin (PCDD), dibenzofurans (PCDFs), and heavy metals. Furthermore, medical waste ash appears to have high leachability in the toxicity characteristics leaching procedure (TCLP) test and the European standard test (EN 12457). Owing to its toxicity, medical ash can be treated using various methods prior to disposal based on the covered review. These techniques include chemical, supercritical fluid, cement-based, melting, microwave, and mechanochemical techniques. The shortcomings of some of these treatment methods have been identified, such as the emission of high levels of chlorine from the melting technique, limited applications of the flotation method on the industrial scale, long-term stability of leachate treated by cement-based methods that have not been confirmed yet, and high energy consumption in the supercritical technique. This review also covers possible applications of medical waste ash in cement production, agriculture, and road construction. [ABSTRACT FROM AUTHOR]

In Nigeria, artisanal mining has become a serious issue. In the Nigerian mining region of Arufu Pb–Zn–F, this study assessed the level of pollution, ecological hazards, and health risks related to the presence of metals in the water. In the dry and rainy seasons, 36 water samples (20 from the ground, 10 from the surface, and six from the mine) were gathered. Samples were examined for the presence of heavy metals such as Cr, Co, Ni, Cu, Zn, As, Cd, and Pb. Other than Cu, Zn, As, Cd, Sb, and Cd (surface water, dry season), which were below the acceptable norm, all water samples had metals over the suggested limits. Heavy metals from nearby mining activities polluted the water, according to contamination evaluations utilizing the contamination factor (CF). Metals in the water may pose very significant ecological dangers, according to ecological risk assessments. The evaluation of human health risks revealed that both adults and children in the region are susceptible to carcinogenic and non-carcinogenic health hazards since the hazard index (HI) values for both indices were above 1* ( 10-5 and above 1, respectively. This report emphasizes the need for monitoring mining operations in the nation to safeguard public health [ABSTRACT FROM AUTHOR]

We investigated the effects of ultrasound-assisted ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) washing on heavy metal (HM) removal, residual HM mobility, and sewage sludge quality. EDTA and CA washing of sewage sludge successfully reduced the total concentration of HMs after one round of washing, but the mobility of residual HMs increased significantly. The eluate had a high concentration of HMs and nutrients (nitrogen, phosphorus, potassium, and total organic carbon), although the nutritional content of the sludge remained high. The three-phase ratio of the sludge after six rounds of washing by CA was closest to the ideal three-phase ratio, and the degree of influence on the physical structure of the soil after a land application was reduced, according to the fluctuation of generalized soil structure index (GSSI) and soil three-phase structure distance (STPSD) values. The results indicate that CA as an environmental-friendly washing agent can be the superior choice for sludge HM washing; single washing of sewage sludge may increase the mobility of residual HMs, so multiple washings should be considered for land application of sludge. HIGHLIGHTS Ultrasound-assisted chemical washing is a useful and efficient solution to remove HMs from sewage sludge.; The higher concentration (≥0.4 M) of biodegradable CA eluent could effectively reduce HMs in the sewage sludge compared to the traditional non-biodegradable EDTA eluent.;

Nanotechnology has been increasingly explored for the treatment of various waste streams. Among different nanoparticles, nanoscale zerovalent iron (nZVI) has been extensively investigated due to its high reactivity and strong reducing power. However, conventional methods for the synthesis of nZVI particles have several limitations and led to the green synthesis of nZVI using plant-based materials. Plant extracts contain various reducing agents that can be used for nZVI synthesis, eliminating the need for toxic chemicals, and reducing energy consumption. Additionally, each plant species used for nZVI synthesis results in unique physicochemical properties of the nanoparticles. This review paper provides an overview of plant-based nZVI particle synthesis, its characteristics, and its application for the removal of different classes of pollutants such as dyes, heavy metals, nutrients, and trace organic pollutants from water. The review shows that continued research on plant-based nZVI particles to fully understand its potential in wastewater treatment, especially for the removal of a wider variety of pollutants, and for improving sustainability and reducing the cost and environmental impact of the process, is necessary. HIGHLIGHTS A variety of plants and plant parts can be used for the synthesis of nanoscale zerovalent iron particles.; Plant-based nZVI particles show improved material characteristics.; A variety of water contaminants can be removed using plant-based nZVI.; Studies indicate that plant-based nZVI can be successfully regenerated.; More studies for improving sustainability and reducing the cost of synthesis are necessary.;

The rate at which freshwater sources are being contaminated by mining operations in the South-Western part of Ghana is alarming. However, no study has quantified the degree of contamination of the freshwater in such areas, leaving a gap in the literature that requires immediate attention. This study assessed the quality of the surface and groundwater in the Tarkwa Nsuaem Municipality. Even though the physical parameters such as pH and electrical conductivity were indicative of safe freshwater, other parameters such as turbidity, total suspended solids (TSS), dissolved oxygen (DO), and heavy metals in the water sources were high; thus, confirming possible leaching, runoff, and dissolution of the hazardous substances employed in the manganese mining operations. The water quality of 82% of the water sources along the Kawere Stream was low (Classes III and IV). Therefore, the local people are at risk of contracting water-related diseases, and health problems associated with the ingestion of Fe, As, and Mn. The findings in this study are important in establishing the rate at which mining operations are reducing the quality of freshwater in developing countries, and potentially affecting human health. HIGHLIGHTS The local people around the Kawere Stream depend more on groundwater due to the non-potable state of the stream.; The public health of the local people may be a major issue in the nearest future if the contaminants present in the groundwater are life-threatening.; 82% of the water sources are of poor quality.; Fe, As, and Mn contribute immensely to water contamination.; Indigenes are at risk of water-related diseases.;

Microalgae–bacteria systems are used for the treatment of effluents, using a technology that has stood out with excellent results, as reported in the literature. However, investigating these systems in more depth can improve our understanding of the removal mechanisms for a wide range of existing and emerging pollutants and help improve the guidelines for design and operation, in order to improve the treatment efficiency as well as biomass productivity. This work studied the impact of the feeding regime on the removal of metals and pathogens from primary domestic wastewater in high rate algal ponds (HRAPs). For this, one reactor was fed continuously (HRAP1) while two reactors were fed in semi-continuous mode, during 12 h day−1 (HRAP2) and 0.1 h day−1 (HRAP3). Although removal efficiencies of 82 ± 5% for Mn and 90% for E. coli were reached in the semi-continuously fed reactors, there was no significant difference between the conditions studied. On the other hand, for biomass productivity, the semi-continuous feeding regime was more advantageous with a growth of ≈ 22 mg L−1 day−1. HIGHLIGHTS There was no significant difference in metal removal among the investigated feeding regimes.; For the two feeding regimes, good removals were obtained for metals, like Fe, Mn and Cr, with averages of 81 ± 20; 83 ± 3 and 51 ± 3%, respectively.; The reactor feeding regime did not influence E. coli removals, which reached up to 99%.; Higher biomass productivity was achieved in semi-continuously fed HRAPs with ≈22 mg L−1 day−1.;

Heavy metals' contamination of water resources is a global environmental issue due to their detrimental effects on human health. To safeguard humans and the environment, toxic heavy metals must be removed from contaminated water because they cannot be broken down. Diverse technologies are employed to reduce the levels of heavy metals in wastewater. However, these technologies suffer from being either costly or ineffective, particularly when the effluent has extremely low residual amounts. This review outlines the main accomplishments and promising future directions for solvent extraction as one of the potential methods of extracting heavy metals from water, utilizing literature reports. In addition to reviewing some of the commercial chelating reagents now in use, this article also discusses some of the obnoxious effects on human health that are associated with exposure to heavy metals. HIGHLIGHTS Water pollution by heavy metals is a global issue.; Some heavy metals are toxic to plants and human life.; Chelation extraction of heavy metals is a potential technology for remediation of heavy-metal polluted water.; Chelation extraction is potentially more efficient and selective.; With respect to green chemistry principles such as solvent-free technique, functionalization of mesoporous silica is a promising alternative.;

In this research, an innovative type of sediment resource treatment agent (SRA) was synthesized successfully, which could immobilize ammonia nitrogen (NH3-N), total phosphorus (TP), potassium (K), and simultaneously stabilize cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn) in dredged sediment. The effects of SRA dosage on stabilizing the nutrient elements and heavy metals were investigated. The results demonstrated that the increase of SRA dosage significantly enhanced the stabilization of nutrients and heavy metals. The 14-day rainwater infiltration and rainwater scouring experiments were carried out. With the simulation test of rainwater infiltration, the stabilization ratios of Cr, Cu, Ni, Pb, Zn, Cd, NH3-N, TP, and K with 2% SRA addition reached 80.8%, 76.8%, 80.3%, 77.5%, 78.0%, 72.7%, 64.3%, 73.9%, and 73.9%, respectively. Under the action of rainwater scouring, the stabilization ratios of Cr, Cu, Ni, Pb, Zn, Cd, NH3-N, TP, and K with 6.4% SRA addition reached 84.6%, 84.0%, 77.6%, 87.3%, 80.0%, 61.5%, 76.2%, 77.8%, and 91.7%, respectively. Therefore, the results demonstrate that SRA is an excellent composite material in stabilizing heavy metals while reserving the nutrients in dredged sediment, thus showing great potential in the application for dredged sediment resource treatment. HIGHLIGHTS Stabilized heavy metals and nutrient elements were achieved simultaneously.; The stabilization under various test conditions was demonstrated.; The influence of SRA on sediment pH was investigated.; SRA could change the anaerobic environment of dredged sediment by releasing oxygen.; The stabilizing mechanisms on contaminants were elucidated.;

Indiscriminate industrialization and urbanization have negatively impacted our environment. One of the common environmental problems in semi-urban areas in India is the discharge of inefficiently treated municipal, industrial and domestic wastewater into the environment, resulting in the degradation of soil and water qualities. Depleting freshwater resources have led Indian farmers to look for easily available, cheaper, and nutrient-rich sources of irrigation water in the form of wastewater; however, this also led to increased pollutant transfer to the soils. Known as persistent pollutants, heavy metals such as cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb), mercury (Hg), and a few others are potentially hazardous due to their non-biodegradable nature, extended biological half-lives, and biological interactions. These heavy metals can bind to soil surfaces and then be absorbed by plant tissues. Vegetables supply micronutrients, antioxidants, vitamins, and other nutrients essential for human growth. Therefore, the consumption of vegetables/crops grown in wastewater-irrigated land poses a potential threat to humans. Since wastewater irrigation cannot be eliminated in the Indian (semi-)urban areas because of the ever-increasing demand for irrigation water, it is important to assess the impact of wastewater irrigation. This review article congregates the findings of studies from India wherein heavy metal contaminations in vegetables have been reported. An attempt was made to estimate the risk to human health because of the long-term consumption of vegetables cultivated in wastewater-irrigated lands from the Indian sites. HIGHLIGHTS Heavy metals in vegetables produced from wastewater-irrigated croplands in India.; Common sources contribute to heavy metals in soils.; Geochemistry of heavy metals regulates the transfer factor more than plant physiology.; Risk to human health associated with heavy metals.;

The study of the modulation of the toxicity of heavy metals by coexisting chemicals in the environment is vital for realistic ecological risk assessment. Our study was aimed at determining possible toxicity modulations of Cd by humic acid (HA) using the Allium cepa test system. A. cepa bulbs were exposed to Cd (1 and 5 mg/L) and HA (10 mg/L) individually or in mixtures. The root lengths of the bulbs and cytogenetic endpoints in root meristematic cells, including the mitotic index (MI), nuclear abnormalities (NAs), and chromosomal abnormalities (CAs), were determined. The results revealed that the MIs of A. cepa co-exposed to HA and Cd were significantly recovered by >15% compared with those of A. cepa subjected to Cd-only treatments, and this response was more sensitive than the phytotoxic response (root length). Furthermore, the burden of NAs was significantly decreased in the co-exposed bulbs by >20% compared with bulbs with Cd-only treatments. The frequencies of CAs were also reduced in the bulbs co-exposed to HA and 1 and 5 mg/L Cd by >15 and >25%, respectively, compared with bulbs receiving Cd-only treatments. Therefore, our findings indicated that HA plays a significant protective role in Cd toxicity in A. cepa. HIGHLIGHTS Allium cepa was used to determine the modulation of Cd toxicity by humic acid using microscopic and macroscopic endpoints.; Humic acid induced the recovery of the inhibited mitotic index and root lengths caused by Cd stress.; The burdens of nuclear and chromosomal abnormalities were alleviated by humic acid.; Humic acid plays a protective role against Cd toxicity in the A. cepa test system.;

Pollution of industry-adjacent surface water bodies has become a major threat to the environment in Bangladesh. This study examined the health risks of concentrated heavy metals in Tongi, Shitalakkhya, and Dhaleshwari, which receive effluents from wastewater treatment plants. Samples were analyzed for heavy metals such as lead, cadmium, iron, magnesium, manganese, zinc, copper, chromium, and nickel. At all the locations, only Zn, Cu, and Ni did not exceed the Bangladesh standard for drinking water. The health risk was estimated using the hazard quotient (HQ) technique. There was a threat of health risks resulting from the exposure through ingestion, with Pb, Cd, Fe, Mg, and Cr being the main contributors. The orders of decreasing values of mean HQ were Mg > Pb > Fe > Cr > Cd, Mg > Fe > Pb > Cr > Cd, and Cr > Mg > Pb > Fe > Cd via oral intake for both adults and children at Tongi, Shitalakkhya, and Dhaleshwari, respectively. For dermal intake, the mean HQ for only chromium at Dhaleshwari exceeded the limit for both groups. The results emphasize the need for enhancement, proper operation, and maintenance of wastewater treatment facilities in order to meet the discharge quality standard. HIGHLIGHTS The river waters in Bangladesh are heavily polluted due to textile wastewater discharge.; Heavy metals such as Pb, Cd, Fe, Mg, and Cr are the main contributors.; The HQ values of Pb, Cd, Cr, Fe, and Mg are higher than 1 for both oral and dermal intake in all sampling locations of the study.; The results indicate a significant level of health risk and a poor state of the wastewater treatment systems employed in the textile industries.;

In developing countries, the stress of drinking water is often due to the increase in population, and rivers are the most important source of water. In this study, the pollution of the Kadambrayar River, located in southern India, was evaluated. The river flows through major establishments in the city, and an open dumping site is located near its bank. The river was infested with water hyacinth, which is considered a bioindicator of pollution in water bodies. Sixteen water quality parameters were analyzed across eight sampling stations in the river and compared with the standard limits as per IS 10500:2012 and IS 2296:1992, WHO, ICMR. It was found that parameters such as DO, BOD, and Coliforms did not comply with the limits at any of the stations. The heavy metals were also analyzed for water and sediment samples, in which the concentrations of arsenic in water were seven times higher and chromium was 50 times higher than the national standard limit. Thus, it can be concluded that the quality of this drinking water source is declining abruptly, especially downstream near the dumpsite, affecting the ecosystem as well as human health when exposed to carcinogenic metals. HIGHLIGHTS The river Kadambrayar is an important drinking water source for the surrounding urbanizing region.; The river is infested with water hyacinth, which is a bioindicator of pollution.; More than 500 MPN/100mL of coliforms are present in the river at all stations.; The highest BOD of 228 mg/L and the lowest DO concentration was 0 mg/L for samples from a drain that carried the effluent from the industries to the river.; The highest arsenic and chromium contamination in sediment and water samples was obtained downstream near the open dumping site.; Exposure to heavy metal-contaminated drinking water can cause skin disorders, and cancer in humans and also threaten the survival of aquatic biodiversity.;

The quality of the surface water along the Kunhar River in Mansehra district, KPK Pakistan was assessed for ten water samples stations. A variety of parameters indicating water quality including physicochemical parameters, nutrients, heavy metals, and antibiotic residues were measured for both the rainy and dry seasons, the two main tropical seasons in Mansehra, using the standard methods. Kunhar River, one of the local drinking water sources, was studied to assess the heavy metal content, health risk assessment, and its suitability for human consumption. Health risk assessment for all the stations indicated that there is no particularly dangerous single heavy metal, but their cumulative effect is indicated by the hazard index. Concentrations of metals in water have a trend of decreasing in water, indicating that the accumulation of metals can affect the water chemistry of aquatic systems due to any physical or chemical process in the system. Greater consideration should be given to the variety of metals in relationship to multivariate analyses, suggesting that the industrial and residential activities were more important contributors to the pollution of the Kunhar River than the agricultural activities in Mansehra district. Such metals pose risks to aquatic life. HIGHLIGHTS In the Kunhar River, seasonal fluctuations in the levels of nutrients, toxic substances, as well as certain antibiotics were identified.; The study revealed that domestic activities caused significantly more environmental damage to the Kunhar River than agricultural practices.; High-pollution sites of the Kunhar River have been affected by human settlement.;

Human beings are frequently exposed to a mixture of chemical pollutants through the ingestion of contaminated drinking water. The present study aimed to assess the ecological and human health risks associated with the contamination of cyanotoxins and heavy metals in a drinking water supply reservoir, the Tri An Reservoir (TAR), in Vietnam. Results demonstrated that the concentrations of individual heavy metals varied in the following order: iron (Fe).lead (Pb).arsenic (As).zinc (Zn). Although the ecological potential risk of heavy metals was low during the study period, the concentration of Fe sometimes exceeded the Vietnamese standard for drinking water. Toxic cyanobacteria and microcystins (MCs) frequently occurred in the TAR with the highest density of 198.7× 10³ cells/mL and 7.8 µg/L, respectively, indicating a high risk of health impacts to humans. The results of the study indicate that exposure to heavy metals does not pose any non-carcinogenic health risks for both adults and children. However, the contamination of MCs in the surface water posed a serious disease enhancement to both adults and children through direct ingestion and dermal absorption. [ABSTRACT FROM AUTHOR]

The rate at which freshwater sources are being contaminated by mining operations in the South-Western part of Ghana is alarming. However, no study has quantified the degree of contamination of the freshwater in such areas, leaving a gap in the literature that requires immediate attention. This study assessed the quality of the surface and groundwater in the Tarkwa Nsuaem Municipality. Even though the physical parameters such as pH and electrical conductivity were indicative of safe freshwater, other parameters such as turbidity, total suspended solids (TSS), dissolved oxygen (DO), and heavy metals in the water sources were high; thus, confirming possible leaching, runoff, and dissolution of the hazardous substances employed in the manganese mining operations. The water quality of 82% of the water sources along the Kawere Stream was low (Classes III and IV). Therefore, the local people are at risk of contracting water-related diseases, and health problems associated with the ingestion of Fe, As, and Mn. The findings in this study are important in establishing the rate at which mining operations are reducing the quality of freshwater in developing countries, and potentially affecting human health. [ABSTRACT FROM AUTHOR]

The present study aimed to assess the health risks of chemical contaminants of residents in the coastal areas of Cambodia through their drinking water pathways. Water was sampled from tube wells (n = 22), dug wells (n = 31), ponds (n = 11), canals (n = 12) and lakes (n = 4) across the Cambodian coastal areas, and measured for the contaminants of health concern (As, Cu, Cr, Cd, F−, NO2-, NO3-, Pb, Escherichia coli and total coliform) and aesthetic quality following the United States Environmental Protection Agency (USEPA) and standard methods. Analytical results reveal that 9.1% of tube wells and 9.7% of dug wells contained As > 0.01 mg/L. Appropriately, 22.7% of tube wells and 32.3% of dug wells contained Fe > 0.3 mg/L while 100% of tube wells and 80.6% of dug wells contained Mn > 0.1 mg/L. Health risk assessment found that the hazard quotient (HQ) > 1 for children and women. Additionally, the lifetime cancer risk (LCR) was found >1 × 10−4 for As in Cambodian coastal areas. Therefore, a monitoring programme and appropriate treatment to remove contaminants like arsenic, cadmium and fluoride would be required to ensure a safe drinking water supply to Cambodian coastal residents. HIGHLIGHTS Both total coliform and E. coli were found in the tube well, dug well, ponds, canals and lakes while the Cambodian Drinking Water Quality Standard for total coliform and E. coli is not detectable per 100 mL.; Health risk assessment revealed that for children and women residing in the coastal areas of Cambodia had HQ > 1.; Men, women and children residing in the coastal areas of Cambodia are exposed to carcinogenic risk of As through drinking water pathways.;

Heavy metals pollution of both surface and groundwater sources of sub-Saharan Africa is alarmingly increased due to unplanned urban populations. Inadequate policies for water management, political commitment, and financial resources forced 65% of rural communities of sub-Saharan Africa to live in economic water stress areas. Sugarcane bagasse (SCB) shows high heavy metals (HMs) adsorption capacity (20–700 mg/g) through chemical entrapments to carbon-oxygen containing functional group and interior pore filling of porous surface. Various modifications like a physical/thermal, chemical, and composite form of bagasse show better adsorption performance for HMs removal. Kinetic and isotherm studies of HMs adsorption equilibrium data over SCB show that both Langmuir and Freundlich adsorption isotherms (cooperative adsorption) as the main adsorption mechanism. In addition, SCB shows potential bio-adsorbent properties for the selective adsorption of target HMs based on their physicochemical properties and shows good repeatability in acid environments. It is believed that information on this review will shed light on the current and future prospects of raw and modified SCB for HMs adsorption removal capacity. Sugarcane bagasse shows a remarkable selectivity for HMs adsorption removals based on their physicochemical properties and shows good potential capability for future utilizations in real wastewaters of developing countries. HIGHLIGHTS Bio-adsorbent (e.g. sugarcane bagasse) can be regenerated.; Sugarcane bagasse has high adsorptive capacity for both anion and cation heavy metals.; Cooperative adsorptive mechanism is well explained by Freundlich and Langmuir isotherms.;

In this work, heavy metals were removed simultaneously using wheat bran as an adsorbent. For batch experiments, the Box–Behnken design of response surface methodology was used and the effect of dye on metal removal was analysed. It has been observed that the presence of dye has reduced the removal of each metal in the range of 100–20% with no appreciable reduction in dye adsorption. The optimum pH, temperature, and adsorbent dose were found to be 7.59, 33.23 °C, and 2.90 g/L, respectively, for 79.70% chromium, 99.9% cadmium and 87.27% copper removal. It was found that Langmuir isotherm fits well with the experimental data (RMSE value up to 0.033). The maximum adsorption capacity obtained for copper, chromium, cadmium and dye were 2.17 mg/g, 1.76 mg/g, 1.52 mg/g and 3.215 mg/g, respectively. The continuous study was performed for parameters, i.e. bed height (0.15–0.45 m), flow rate (5–15 mL/min) and initial metal concentration (100–500 mg/L). In continuous study, dye acted as an interfering species and as a result breakthrough and exhaustion time decreased. The modelling and simulation of continuous adsorption process were performed. A dynamic mathematical model was developed for continuous fixed bed adsorption column to compare the breakthrough curve with experimental results. HIGHLIGHTS A very limited study has been done for simultaneous removal of heavy metals and dyes, therefore the work of this manuscript will be a contribution to the community. This is the novelty of this manuscript.;

Urban watercourses are under pressure owing to the inflow of environmental pollutants from stormwater and effluent. The concentrations of heavy metals, ammoniacal nitrogen, total phosphorus (TP), and physicochemical parameters were monitored in a sediment pond in the Brazilian Midwest. The correlation between the variables and the degree of sediment contamination was verified using the Geoaccumulation Index (Igeo), Contamination Factor (CF), and Pollutant Load Index (PLI). The general concentrations of the metals were in the order Mn > B > Ba > Zn > Cu > Cr > Pb > Ni in the water and Mn > Cr > Ba ≥ B > Zn > Cu > Ni > Pb in the sediment. The concentrations of Ba, Cr, Cu, Mn, Ni, Pb, and TP in the water exceeded the regulatory limits at least one time. The mean concentrations of Cr, Cu, and Ni in the sediment samples were 6.32, 1.63, and 2.61 higher than standard values. The applied geochemical indices indicated a moderate to a very high degree of sediment contamination, suggesting the anthropogenic origin of Cr, Cu, and Ni. Significant Pearson correlations were observed between turbidity and total suspended solids (TSS), Ba, Cr, Mn, Zn, and TP. Ponds and urban lakes require maintenance or may become a source of environmental pollutants. HIGHLIGHTS We assessed annual water and sediment quality of stormwater ponds.; Water, TF showed a strong correlation with turbidity, TSS, Ba, Cr, Mn, and Zn.; Sediment, Cr, Cu, and Ni were 6.32, 1.63, and 2.61 higher than the background values.; Sediment, TF concentrations during the dry season exceeded legislative limits by an average of 1.73 times.; Cu and Zn were not correlated with precipitation.;

Accumulation of water treatment sludge is a major environment problem in the water purification process. Recovery of waste constituents or reuse of sludge is a cost-effective method in handling this environmental dilemma. The present study investigates the suitability of sludge in the production of bricks and recovery of aluminum from the sludge accumulated at the Biyagama drinking water treatment plant (BDWTP) in Sri Lanka. The chemical parameters of total organic carbon, pH, total nitrogen content, total phosphorous content, heavy metals, and cation exchange capacity in samples were analyzed in different turbidity periods. The aluminum recovery was investigated both by acidic and by alkaline leaching processes. A mixing ratio of 3:1 (clay:water treatment sludge) was found to be suitable for manufacturing bricks having compressive strength, efflorescence, and water absorption parameters according to SLS 39:1979. The metal composition of manufactured bricks was compared with clay and water treatment sludge. The environmental impact of current landfilling was estimated by analyzing the leachate of this sludge for COD, NO3-, NO2-, PO43-, free NH3, SO42-, and metals. The heavy metal leachability of manufactured bricks was also analyzed to establish its suitability as an eco-friendly product. HIGHLIGHTS Disposing sludge is a major environmental problem in the water management process.; Recovery process of aluminum should be done prior to the sludge treatment process.; Manufacturing of bricks using sludge is an environmentally benign (green) process.;

Endocrine disruptors (EDs) such as bisphenol A (BPA), nonylphenol (NP), octylphenol (OP) and heavy metals in drinking water supply represent a significant threat to human health. In Nigeria, little is known about the presence of EDs in various environmental media. This study was conducted to determine the concentrations of BPA, NP and OP in groundwater samples from selected communities in Ibadan, Nigeria. Water samples were collected from 30 different sites (26 hand-dug wells, 2 boreholes and 2 spring water sources), 15 from each of Ibadan North-West (IbNW) and Ido Local Government Area (LGA). Samples were collected in triplicate from all the sampling points and analysed for BPA, NP, OP and physicochemical parameters (including heavy metals) using a standard procedure. Bisphenol A and octylphenol were not detected in any samples, while NP was detected in spring water and the concentration (0.00279 mg/L) was less than the maximum allowable limit (0.015 mg/L). All (100.0%) boreholes in IbNW and 100.0% of the springs in Ido LGA showed iron concentrations that exceeded the permissible limit. There is a need for public awareness on the health risk of EDs in drinking water supply and appropriate preventive measures to be adopted. [ABSTRACT FROM AUTHOR]

Artisanal and small-scale gold mining (ASGM) activity in Way Ratai River produces heavy metal wastes; therefore, further information regarding heavy metal concentrations in the water was needed, especially in plankton samples. Furthermore, the determination of plankton diversity was also carried out in the waters of Way Ratai to determine the bioconcentration factor (BCF). Eight sampling sites were chosen along the river reaching the coast of Way Ratai. The research was conducted in November 2020 and March 2021. Ten heavy metals, Ag, Cd, Co, Cr, Cu, Fe, Mn, Pb, and Zn that are commonly found in mining areas, were determined in the water and plankton samples by using ICP-OES. The results indicated that the highest concentration found was Fe in plankton samples (0.725 mg/L in the river and 1.294 mg/L on the coast). Meanwhile, contents of Cd, Cu, Fe, Mn, and Zn in the river exceeded the predetermined water quality standards, while Ag and Pb metals were not detected. The Cd, Cr, Cu, Pb, and Zn content in seawater also exceeded quality standards. The highest BCF value (12.96) was found for Fe at station G, whereas the lowest BCF value (0.13) was found for Ag at stations G and H. [ABSTRACT FROM AUTHOR]

To investigate the potential health risk of trace elements in the Tonle Sap Great Lake system, lake (n=37) and river (n=14) water samples were collected and analyzed for 19 trace elements (Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Se, Tl, U and Zn) using inductively coupled plasma mass spectrometry. As a result, Cd was not detected in any river and lake water samples. Al, Fe and Mn in lake water exceeded the regulation limits of Cambodia, USEPA and WHO. Health risk assessment using the USEPA model indicated that male and female Cambodian residents are at minimal risk of non-carcinogenic effects from single and mixed trace elements through lake and river water consumption. Nevertheless, As, Tl, Co, Ba, Mn and Cr might pose high potential health risks to consumers which requires more attention. Therefore, regular monitoring and further studies are required to investigate the pollution trends and toxic behavior of these trace elements in the Tonle Sap Great Lake system. [ABSTRACT FROM AUTHOR]

Pollution of industry-adjacent surface water bodies has become a major threat to the environment in Bangladesh. This study examined the health risks of concentrated heavy metals in Tongi, Shitalakkhya, and Dhaleshwari, which receive effluents from wastewater treatment plants. Samples were analyzed for heavy metals such as lead, cadmium, iron, magnesium, manganese, zinc, copper, chromium, and nickel. At all the locations, only Zn, Cu, and Ni did not exceed the Bangladesh standard for drinking water. The health risk was estimated using the hazard quotient (HQ) technique. There was a threat of health risks resulting from the exposure through ingestion, with Pb, Cd, Fe, Mg, and Cr being the main contributors. The orders of decreasing values of mean HQ were Mg . Pb . Fe . Cr . Cd, Mg . Fe . Pb . Cr . Cd, and Cr . Mg . Pb . Fe . Cd via oral intake for both adults and children at Tongi, Shitalakkhya, and Dhaleshwari, respectively. For dermal intake, the mean HQ for only chromium at Dhaleshwari exceeded the limit for both groups. The results emphasize the need for enhancement, proper operation, and maintenance of wastewater treatment facilities in order to meet the discharge quality standard. [ABSTRACT FROM AUTHOR]

The Yamuna River is a threatened resource of freshwater in Delhi, India. The present study is focused on investigating three important contaminants, namely microplastics (MPs), heavy metals, and fecal coliforms in the surface water of the river, with major emphasis on MPs occurrence and characterization. MPs showed an increase in abundance in the river from the Wazirabad barrage (n = 500 MPs/m3) to the Okhla barrage downstream (n = 3,900 MPs/m3) in Delhi, with a maximum abundance downstream to the Najafgarh and Shahdara drain outfalls. White color and fragmented shape were prevalent characteristics of the isolated MPs. Attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy revealed five types of polymers. Heavy metals (chromium, lead, manganese, and iron) and fecal coliforms were at unacceptable levels at most of the sampling sites. Due to the emergence of issues concerning the tendency of MPs to actively interact with heavy metals and pathogenic microorganisms, investigation of the co-occurrence of such harmful pollutants is very important. The present study is aimed at this issue and urges similar kinds of investigations in other riverine regions of our country, as well as globally, due to their scarcity in literature. This study can further provide a baseline database to help the Government of India's efforts to clean and revive the Delhi stretch of the Yamuna River. HIGHLIGHTS Microplastics (MPs) were prevalent across the Yamuna River stretch with a mean abundance of 1.78 × 103 MPs/m3.; MPs were most abundant near the wastewater discharge points of the Najafgarh and Shahdara drains.; In addition to MPs, the presence of co-contaminants like heavy metals and fecal coliforms in the study area was also a serious concern.; Co-contaminant interactions may disturb the balance of several biological systems.;