Uncovering nano-bonechar for attenuating fluoride in naturally contaminated soil.

Fluoride ion (F-) is one of the major geogenic contaminants in water and soil. Excessive consumption of these geogenic contaminants poses serious health impacts on humans and plants. In this study, a novel carbonaceous material, nano-bonechar, was synthesized from cow bones and applied as a soil amendment at rates of 0, 0.5, 1, and 2% to remediate and revitalize naturally F--contaminated soil. The results revealed that the nano-bonechar significantly reduced the mobility and bioavailability of F- by 90% in the contaminated soil, and improved the soil quality by increasing the soil water holding capacity, soil organic matter, and the bioavailable contents of PO43-, Ca2+, and Na+. Subsequently, the pot experiment results showed a significant reduction in the uptake of F- by 93% in Zea mays plants. Moreover, the nano-bonechar application improved the plant's growth, as indicated by the higher fresh and dry weights, root and shoot lengths, and total content of PO43-, Ca2+, and K+ than those of un-amended soil. The F-immobilization in soil was mainly due to the presence of the hydroxyapatite [Ca10(PO4)6(OH)2] mineral in the nano-bonechar. Ion exchange between OH- (of nano-bonechar) and F- (of soil), and the formation of insoluble fluorite (CaF2) contributed to the attenuation of F- mobility in the soil. It is concluded that nano-bonechar, due to its size and enrichment in hydroxyapatite, could successfully be utilized for the rapid remediation and revitalization of F--contaminated agricultural soil.

Environmental pitfalls and associated human health risks and ecological impacts from landfill leachate contaminants: Current evidence, recommended interventions and future directions.

The improper management of solid waste, particularly the dumping of untreated municipal solid waste, poses a growing global challenge in both developed and developing nations. The generation of leachate is one of the significant issues that arise from this practice, and it can have harmful impacts on both the environment and public health. This paper presents an overview of the primary waste types that generate landfill leachate and their characteristics. This includes examining the distribution of waste types in landfills globally and how they have changed over time, which can provide valuable insights into potential pollutants in a given area and their trends. With a lack of specific regulations and growing concerns regarding environmental and health impacts, the paper also focuses on emerging contaminants. Furthermore, the environmental and ecological impacts of leachate, along with associated health risks, are analyzed. The potential applications of landfill leachate, suggested interventions and future directions are also discussed in the manuscript. Finally, this work addresses future research directions in landfill leachate studies, with attention, for the first time to the potentialities that artificial intelligence can offer for landfill leachate management, studies, and applications.

Food-mediated exposure of Hofmeister ions in Oryza sativa (Rice) from selected CKDu endemic regions in Sri Lanka.

The objectives of this study were to determine selected Hofmeister anions and cations that are important for kidney health, in raw rice samples from selected Chronic Kidney Disease of unknown etiology (CKDu) endemic and non-endemic areas in Sri Lanka and their intake. The anions and cations were analyzed by Ion Chromatography and Microwave Plasma Atomic Emission Spectrometry (MP-AES), respectively, after alkaline and acid digestion in thirty raw rice samples each from CKDu endemic and non-endemic areas, and the dietary intake was estimated. The mean concentrations of fluoride (F-), chloride (Cl-), phosphate (PO43-), sulfate (SO42-), sodium (Na+), magnesium (Mg2+), potassium (K+), and calcium (Ca2+) in raw rice in CKDu endemic areas were 53.317, 1515.3, 2799.6, 2704.9, 30.603, 300.76, 1001.3, and 90.075 mg/kg, respectively. The mean concentration of the anions and cations in raw rice from CKDu non-endemic areas were 22.850, 947.52, 4418.7, 6080.2, 23.862, 364.45, 955.78, and 96.780 mg/kg, respectively. Significantly higher differences (p < 0.05) were reported in the mean concentration of F-, Cl-, and Na+ in raw rice from CKDu endemic areas in comparison with the samples from non-endemic areas. The aggregated estimated daily intake (EDI) and cumulative EDI of F- via consumption of cooked non-traditional samba rice from CKDu endemic areas for adults were the highest (0.155 and 0.172 mg/kg bw/d, respectively), which were higher than the recommended tolerable upper intake value (0.15-0.2 mg/kg bw/d). In contrast, the traditional rice from CKDu non-endemic areas for adolescents, reported the lowest values (0.0210 and 0.0470 mg/kg bw/d, respectively). Adults who consume non-traditional samba rice from CKDu endemic areas were at health risk, while children were the most vulnerable group due to their low body weight. These results indicate that the consumption of rice rich in Hofmeister ions may contribute to the total intake and act as risk factors to negatively affect weak kidneys in CKDu endemic areas. Further research to analyze Hofmeister ions in cooked rice and rice from different countries is recommended.

Enhanced adsorptive removal of hexavalent chromium in aqueous media using chitosan-modified biochar: Synthesis, sorption mechanism, and reusability.

Hexavalent chromium (Cr(VI)) is deemed a priority contaminant owing to its carcinogenicity, teratogenicity, and mutagenicity towards flora and fauna. A novel Chitosan-modified Mimosa pigra biochar (CMPBC) was fabricated and the efficiency of Cr(VI) oxyanion removal in aqueous systems was compared with the pristine biochar. The instrumental characterization of X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) confirmed the amino modification of MPBC when treated with chitosan. Characteristic features of the Cr(VI) sorptive process by CMPBC and MPBC were examined by performing batch sorption studies. Experimental data suggested that sorption is heavily dependent on pH and the highest adsorption occurred at pH 3.0. The maximum adsorption capacity of CMPBC was 14.6 ± 1.07 mg g-1. It was further noted that the removal efficiency of CMPBC (92%) was considerably greater than that of MPBC (75%) when the solution pH, biochar dose, and initial concentration of Cr(VI) are 3.0, 1.0 g L-1 and 5.0 mg L-1 respectively. The kinetic data were best interpreted by the power function model (R2 = 0.97) suggesting a homogenous chemisorption process. The isotherm data for the removal of Cr(VI) by CMPBC was inferred well by Redlich Peterson (R2 = 0.96) and Temkin (R2 = 0.96) isotherms. Results of sorption-desorption regeneration cycles indicated that the Cr(VI) uptake by CMPBC is not fully reversible. The coexistence of Cr(VI) and Cr(III) on CMPBC was confirmed through the XPS analysis. The electrostatic attractions between cationic surface functionalities and Cr(VI) oxyanions, the partial reductive transformation of Cr(VI) species to Cr(III), as well as complexation of Cr(III) onto CMPBC were identified as the possible mechanisms of mitigation of Cr(VI) by CMPBC. The results and outcomes of this research suggest the possibility of utilizing the CMPBC as an easily available, environmentally sustainable, and inexpensive sorbent to decontaminate Cr(VI) from aqueous media.

The spread of the omicron variant: Identification of knowledge gaps, virus diffusion modelling, and future research needs.

The World Health Organization (WHO) recognised variant B.1.1.529 of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) as a variant of concern, termed "Omicron", on November 26, 2021. Its diffusion was attributed to its several mutations, which allow promoting its ability to diffuse worldwide and its capability in immune evasion. As a consequence, some additional serious threats to public health posed the risk to undermine the global efforts made in the last two years to control the pandemic. In the past, several works were devoted to discussing a possible contribution of air pollution to the SARS-CoV-2 spread. However, to the best of the authors' knowledge, there are still no works dealing with the Omicron variant diffusion mechanisms. This work represents a snapshot of what we know right now, in the frame of an analysis of the Omicron variant spread. The paper proposes the use of a single indicator, commercial trade data, to model the virus spread. It is proposed as a surrogate of the interactions occurring between humans (the virus transmission mechanism due to human-to-human contacts) and could be considered for other diseases. It allows also to explain the unexpected increase in infection cases in China, detected at beginning of 2023. The air quality data are also analyzed to evaluate for the first time the role of air particulate matter (PM) as a carrier of the Omicron variant diffusion. Due to emerging concerns associated with other viruses (such as smallpox-like virus diffusion in Europe and America), the proposed approach seems to be promising to model the virus spreading.

Oil spill remediation by biochar derived from bio-energy industries with a pilot-scale approach during the X-Press Pearl maritime disaster.

Most traditional oil spill clean-up techniques are still laboratory based and are expensive and fairly ineffective. This study investigated the capacity of biochars derived from bio-energy industries in oil spill remediation with a pilot-testing. Three different biochars from bio-energy industries, Embilipitya (EBC), Mahiyanganaya (MBC), and Cinnamon Wood Biochar (CWBC) were assessed for the removal of Heavy Fuel Oil (HFO) at three dosages (10, 25, and 50 g L-1). Pilot-scale experiment was conducted with 100 g of biochars separately in the oil slick of X-Press Pearl shipwreck. All adsorbents exhibited rapid oil removal (within 30 min). Isotherm data were well explained by Sips isotherm model (R2 > 0.98). The pilot-scale experiment resulted oil removal for CWBC, EBC and MBC as 0.62, 1.12, and 0.67 g kg-1 respectively, even in rough sea conditions with a limited contact time (>5 min) indicates biochar's capacity in oil spill remediation as a cost-effective material.

Intake of fluoride and other Hofmeister ions from black tea consumption in CKDu prevalent areas, Sri Lanka.

Dietary exposure of selected Hofmeister ions-fluoride, chloride, sulfate, phosphate, sodium, potassium, magnesium, and calcium from black tea consumption in chronic kidney disease of unknown etiology (CKDu) prevalent areas in Sri Lanka-were assessed in order to understand exposure and risk. Black tea samples (n = 25) were collected from CKDu prevalent areas and control areas (n = 15). Total fluoride content in alkali fused digested black tea samples was determined. The available Hofmeister ions in tea infusions prepared using deionized water and the groundwater collected by CKDu endemic areas were compared. Dietary exposure was calculated by chronic daily intake data. Total fluoride concentrations ranged from 80 to 269 mg/kg in tea collected from the CKDu endemic regions and 62.5-123.5 mg/kg in non-endemic regions. The fluoride content in infusions ranged from 1.45 to 2.04 mg/L in CKDu endemic areas and 1.11-1.38 mg/L in control samples. The infusions prepared with local groundwater from the CKDu endemic areas showed an elevated level of fluoride 95% than that of the infusion prepared using same tea with deionized water. Aggregated chronic daily intake value from tea and groundwater exceeds the estimated adequate daily intake value of fluoride. The hazard quotient (HQ) values of fluoride in 5 min and 120 min tea infusions were 1.60 and 2.20, respectively, and indicate an adverse health risk. Potassium content in tea infusions collected from CKDu endemic areas is higher than in the control. Even though these values are less than the adequate intake, it may pose an impairment on a weak kidney. Chronic daily intake of Hofmeister ions, i.e., fluoride and potassium from black tea consumed in CKDu endemic areas may induce a risk for CKDu.

Temperature influence on layered double hydroxide tailored corncob biochar and its application for fluoride removal in aqueous media.

Exposure to excess fluoride is a controversial public health concern as it can cause dental/skeletal fluorosis as well as renal toxicity. The study intended to evaluate the synergistic interaction of clay intercalation and thermochemical modification on corncob biochar to remove fluoride from aqueous solutions. Layered double hydroxide was assorted with thermally activated (torrefaction and pyrolysis) corncob biochar at 1:1 (w/w) ratio to obtain composites called LDH-CCBC250 and LDH-CCBC500. Physicochemically characterized adsorbents were assessed against the pH (3-9), reaction time (up to 12 h) and initial fluoride concentration (0.5-10 mg L-1) for defluoridation. The porous structure of biochar was found to be richer compared to biocharcoal. The adsorption performance of LDH-CCBC500 was 6-fold higher compared to LDH-CCBC250 signifying the pronounced effect of thermal activation. Fluoride adsorption was pH dependent, and the best pH was in the range of pH 3.5-5.0 and there was no ionic strength dependency. Fluoride uptake by LDH-CCBC500 follows pseudo-second order and Elovich kinetic models, which suggests a chemisorption process followed by physisorption. The most expected way to eliminate fluoride by LDH-CCBC500, which had a maximum adsorption capacity of 7.24 mg g-1, was cooperative chemical adsorption upon the Langmuir and Hills isotherm (r2 = 0.99) parameters. Layered double hydroxide intercalated corncob biochar derived from slow pyrolysis is best performing in acidic waters.

Arsenic removal from aqueous solution: A comprehensive synthesis with meta-data.

Removal of arsenic from drinking water is one of the most important global concerns. Among the various techniques, adsorptive removal of arsenic is considered as a viable most effective method. However, limited attention is given to understand the overall relative sorption capacity of different sorbents (e.g., biocomposite, biochar and nano-composite etc.) since various factors influence the sorption capacity. The aim of this study is to assess the effectiveness of various adsorbents with quantitative estimation (Langmuir adsorption maxima, Qmax) as well as to evaluate the influence of experimental conditions on the achievement of maximum adsorption. A number of analyses including meta-analysis, analysis of variance (ANOVA), scientometric and regression were performed. The results revealed that among the sorbents, nanoparticles show the greatest sorption capacity while pre-doped biochar performed the best among different biochars. Average across all sorbents, As (V) removal efficacy was higher than As (III). As expected, a high point of zero charge (PZC) and higher positive surface charge favored adsorption. The relative contribution of different mechanisms was also discussed. Our scientometric analyses revealed that, research should focus on the development of low-cost adsorbents and increase their reusability, safe disposal of adsorbed arsenic. Altogether, our findings provide a molecular understanding of arsenic sorption to different sorbents with implications for tailoring a good sorbent for arsenic removal from drinking water.

Microplastics and plastics-associated contaminants in food and beverages; Global trends, concentrations, and human exposure.

Microplastics has become a global concern due to their ubiquitous presence which poses unavoidable human exposure risks. Geographical distribution and yearly trends of research on microplastics, food, and beverages do not exist. Thus, no overall account is available regarding the presence of microplastics and plastics-associated contaminants in food and beverages. Hence, this attempt is to review the geographical distribution of studies through a brief bibliometric analysis and the plastics-associated contaminants including plasticizers and microplastics in food and beverages. Estimated microplastic consumption has been listed for the pool of publications reviewed here. Further, this review discusses the ingestion potency of micropollutants associated with microplastics, possible health impacts, and existing challenges. Global trend in research exponentially increased after 2018 and China is leading. Studies on microplastics were limited to a few beverages and food; milk, beer, tea, refreshing drinks, salt, sugar, honey, etc., whereas seafood and drinking water have been extensively studied. Publications on plastic-additives were reported in two ways; migration of plastic-additives from packaging by leaching and the presence of plastic-additives in food and beverages. Bisphenol A and bis(2-Ethylhexyl) phthalate were the most frequently reported both in food and beverages. Exposure of packaging material to high temperatures predominantly involves plastic-additive contamination in food and beverages. Microplastics-bound micropollutants can also be ingested through food and beverages; however, a lack of knowledge exists. The complex matrix of food or beverages and the absence of standard procedures for analysis of microplastics and micropollutants exist as challenges. More investigations on the presence of microplastics and plastic-additives in food and beverage are urgent needs to a better assessment of potential human exposure and human health risk.

Environmental challenges of COVID-19 pandemic: resilience and sustainability - A review.

The emergence of novel respiratory disease (COVID-19) caused by SARS-CoV-2 has become a public health emergency worldwide and perturbed the global economy and ecosystem services. Many studies have reported the presence of SARS-CoV-2 in different environmental compartments, its transmission via environmental routes, and potential environmental challenges posed by the COVID-19 pandemic. None of these studies have comprehensively reviewed the bidirectional relationship between the COVID-19 pandemic and the environment. For the first time, we explored the relationship between the environment and the SARS-CoV-2 virus/COVID-19 and how they affect each other. Supporting evidence presented here clearly demonstrates the presence of SARS-CoV-2 in soil and water, denoting the role of the environment in the COVID-19 transmission process. However, most studies fail to determine if the viral genomes they have discovered are infectious, which could be affected by the environmental factors in which they are found.The potential environmental impact of the pandemic, including water pollution, chemical contamination, increased generation of non-biodegradable waste, and single-use plastics have received the most attention. For the most part, efficient measures have been used to address the current environmental challenges from COVID-19, including using environmentally friendly disinfection technologies and employing measures to reduce the production of plastic wastes, such as the reuse and recycling of plastics. Developing sustainable solutions to counter the environmental challenges posed by the COVID-19 pandemic should be included in national preparedness strategies. In conclusion, combating the pandemic and accomplishing public health goals should be balanced with environmentally sustainable measures, as the two are closely intertwined.

Essence of hydroxyapatite in defluoridation of drinking water: A review.

Hydroxyapatite (HAP) is an easily synthesizable, low-cost mineral that has been recognized as a potential material for fluoride removal. Some of the synthesis methods of HAP are quite straightforward and cost-effective, while some require sophisticated synthesis techniques under advanced laboratory conditions. This review assesses the physicochemical characteristics of HAP and HAP-based composites produced via various techniques, their recent development in defluoridation and most importantly, the fluoride removal performances. For the first time, fluoride removal performances of HAP and HAP composites are compared based on partition coefficient (KD) instead of maximum adsorption capacity (Qmax), which is significantly influenced by initial loading concentrations. Novel HAP tailored composites exhibit comparatively high KD values indicating the excellent capability of fluoride removal along with specific surface areas above 120 m2/g. HAP doped with aluminium complexes, HAP doped ceramic beads, HAP-pectin nanocomposite and HAP-stilbite nanocomposite, HAP decorated nanotubes, nanowires and nanosheets demonstrated high Qmax and KD. The secret of HAP is not the excellent fluoride removal performances but best removal at neutral and near-neutral pH, which most of the defluoridation materials are incapable of, making them ideal adsorbents for drinking water treatment. Multiple mechanisms including physical surface adsorption, ion-exchange, and electrostatic interactions are the main mechanisms involved in defluoridation. Further research work must be focused on upscaling HAP-based composites for defluoridation on a commercial scale.

Inapt management of menstrual hygiene waste (MHW): An urgent global environmental and public health challenge in developed and developing countries.

Menstrual hygiene waste management has received lack of attention and hence it has been poorly investigated, mainly due to its association to social and cultural aspects of a natural process, that is often surrounded of entrenched stigma and taboos. Therefore, data about quantities and full lifecycle of the generated waste are often not available or suffer of large incertitude. However, this argument represents a relevant and critical issue, not only for the health of the women, their equality, and dignity, but also possible associated environmental concerns. This work highlights the necessity and the urgency to face the problems associated with menstrual hygiene waste, which cannot be still considered only relegated to low-income countries. It gives the dimension of the waste associated to migrants in the incoming areas, which is often neglected in sanitation program implementation. This work also describes the existing knowledge gaps and suggests some actions to implement in the next future. In the pandemic context, menstrual hygiene needs urgent attention, also to understand the possible implication of this waste, generated for example in refugees' camps, in SARS-CoV-2 spread, and to prevent eventual unknown environmental issues connected with the reconvention of some factories from the production of menstrual hygiene products to facemasks manufacture.

Phytoremediation prospects of per- and polyfluoroalkyl substances: A review.

Extensive use of per- and polyfluoroalkyl substances (PFASs) in various industrial activities and daily-life products has made them ubiquitous contaminants in soil and water. PFAS-contaminated soil acts as a long-term source of pollution to the adjacent surface water bodies, groundwater, soil microorganisms, and soil invertebrates. While several remediation strategies exist to eliminate PFASs from the soil, strong ionic interactions between charged groups on PFAS with soil constituents rendered these PFAS remediation technologies ineffective. Pilot and field-scale data from recent studies have shown a great potential of PFAS to bio-accumulate and distribute within plant compartments suggesting that phytoremediation could be a potential remediation technology to clean up PFAS contaminated soils. Even though several studies have been performed on the uptake and translocation of PFAS by different plant species, most of these studies are limited to agricultural crops and fruit species. In this review, the role of both aquatic and terrestrial plants in the phytoremediation of PFAS was discussed highlighting different mechanisms underlying the uptake of PFASs in the soil-plant and water-plant systems. This review further summarized a wide range of factors that influence the bioaccumulation and translocation of PFASs within plant compartments including both structural properties of PFASs and physiological properties of plant species. Even though phytoremediation appears to be a promising remediation technique, some limitations that reduced the feasibility of phytoremediation in the practical application have been emphasized in previous studies. Additional research directions are suggested, including advanced genetic engineering techniques and endophyte-assisted phytoremediation to upgrade the phytoremediation potential of plants for the successful removal of PFASs.

Amino-functionalized biochars for the detoxification and removal of hexavalent chromium in aqueous media.

The objectives of the study were to evaluate and compare the efficacy of hexavalent chromium (Cr(VI)) removal by amino-modified (HDA-MPBC) and pristine biochar (MPBC) derived from an invasive plant Mimosa pigra. Prepared biochars were characterized and batch experiments were conducted to check the performance and the mechanisms of Cr(VI) removal. FTIR spectra revealed that the surface of HDA-MPBC is abundant with amino functional groups which was further confirmed by XPS analysis. The highest Cr(VI) removal for both HDA-MPBC (76%) and MPBC (62%) was observed at pH 3.0. The batch sorption data were well fitted to the Freundlich isotherm model and pseudo-second-order kinetic model, suggesting the involvement of both physisorption and chemisorption mechanisms for Cr(VI) removal. X-ray photoelectron spectroscopy studies showed that both Cr(VI) and Cr(III) were presented at the modified biochar surface after adsorption. These results indicated that the electrostatic attraction of Cr(VI) coupled with reduction of Cr(VI) to Cr(III) and complexation of Cr(III) ions with functional groups on HDA-MPBC as the most plausible mechanism for removal of Cr(VI) by modified biochar. Regeneration experiment concluded that adsorbed Cr(VI) onto the surface of HDA-MPBC had the least tendency of being desorbed in basic conditions. HDA-MPBC showed a high performance in adsorptive removal of Cr(VI) compared to pristine biochar signifying the amino modification to enhance adsorption performance of biochar in Cr(VI) removal from wastewater.

Colloidal biochar for enhanced adsorption of antibiotic ciprofloxacin in aqueous and synthetic hydrolyzed human urine matrices.

Objectives of the present research were to examine the capacity of disc-milled high lignin biochar colloids (CBC) for the removal of ciprofloxacin (CPX) from aqueous solution and synthetic hydrolyzed human urine. In this study, adsorption of CPX was tested against the initial pH (3-10), ionic strength (0.001-0.1 M NaNO3), resident time (up to 8 h), initial CPX concentration (5-100 mg/L) and temperature (25, 35, and 45 °C). The surface morphology was examined using Brunauer-Emmett-Teller (BET) specific surface area. The CBC was observed to be < 300 nm whereas the BET surface area was 284 m2/g. Best CPX adsorption demonstrated at pH 5-6 and however, indicated ionic strength dependency. Experimental kinetics data in aqueous media were well-fitted to the pseudo-second-order (r2 of 0.98), while the Hill and Langmuir isotherm models best described the isotherm data (r2 of 0.95 and 0.94, respectively) confirming chemisorption followed by physisorption interactions. The thermodynamics results indicate that CPX adsorption onto CBC is spontaneous (-ΔG), endothermic (+ΔH) and has increased randomness (+ΔS) in the aqueous system. The kinetic experimental data in synthetic urine matrix was fitted with Elovich (r2 = 0.99) and fractional power (r2 = 0.96) models whereas Hills (r2 = 0.99) and Langmuir (r2 = 0.97) models were the most fitted with isotherm data suggesting the adsorption of CPX on the CBC by chemisorption mechanisms. In conclusion, CBC demonstrated effective removal of CPX indicating its potential to be used in wastewater treatment.

Sewage sludge-derived biochar for the adsorptive removal of wastewater pollutants: A critical review.

The production of biochar from sewage sludge pyrolysis is a promising approach to transform the waste resultant from wastewater treatment plants (WWTPs) to a potential adsorbent. The current review provides an up-to-date review regarding important aspects of sewage sludge pyrolysis, highlighting the process that results major solid fraction (biochar), as high-value product. Further, the physio-chemical characteristics of sewage-sludge derived biochar such as the elemental composition, specific surface area, pore size and volume, the functional groups, surface morphology and heavy metal content are discussed. Recent progress on adsorption of metals, emerging pollutants, dyes, nutrients and oil are discussed and the results are examined. The sewage sludge-derived biochar is a promising material that can make significant contributions on pollutants removal from water by adsorption and additional benefit of the management of huge volume of sewage. Considering all these aspects, this field of research still needs more attention from the researchers in the direction of the technological features and sustainability aspects.

A systematic review on adsorptive removal of hexavalent chromium from aqueous solutions: Recent advances.

The contamination of natural resources by hexavalent chromium (Cr(VI)) originating from natural and anthropogenic activities is a serious environmental concern. Although many articles on chromium remediation have been published, a comprehensive understanding of the mechanisms involved in remediation with different sorbents is not yet available. In this systematic review, the performance and applicability of several adsorptive materials for Cr(VI) removal from aqueous media are discussed, along with a detailed analysis of the mechanisms involved. Statistical analysis is applied to compare the efficacies of different adsorbents, while a similar approach is used to determine the effects of sorbent properties and experimental conditions on the adsorption capacity. A detailed analysis of the factors involved in fixed-bed column studies is also presented. A suitable desorption approach to the regeneration of the spent adsorbent and its adsorption performance in reuse is also examined. Among the different sorbents, nanoparticles and mineral-doped biochar were found to be the most effective sorbents, while the adsorption was higher at low pH (~4.0) than that at intermediate pH (6-8). Contrary to our expectation, adsorption was high for sorbents with low specific surface areas, suggesting that the adsorption of Cr(VI) is largely influenced by the chemical properties of the sorbents. The optimum adsorption in fixed-bed column systems is obtained at a lower Cr(VI) ion concentration, a lower influent flow rate, and a higher bed height. Since most of the studies reviewed herein were merely experimental and utilized ideal conditions with the presence of a single contaminant, i.e. Cr(VI) in water, further studies on adsorption dynamics with the presence of other interfering ions are suggested. This review is promising for the further development of Cr(VI) removal strategies and closes the research gaps pertaining to their challenges.

Animal carcass burial management: implications for sustainable biochar use.

This review focuses on existing technologies for carcass and corpse disposal and potential alternative treatment strategies. Furthermore, key issues related to these treatments (e.g., carcass and corpse disposal events, available methods, performances, and limitations) are addressed in conjunction with associated environmental impacts. Simultaneously, various treatment technologies have been evaluated to provide insights into the adsorptive removal of specific pollutants derived from carcass disposal and management. In this regard, it has been proposed that a low-cost pollutant sorbent may be utilized, namely, biochar. Biochar has demonstrated the ability to remove (in)organic pollutants and excess nutrients from soils and waters; thus, we identify possible biochar uses for soil and water remediation at carcass and corpse disposal sites. To date, however, little emphasis has been placed on potential biochar use to manage such disposal sites. We highlight the need for strategic efforts to accurately assess biochar effectiveness when applied towards the remediation of complex pollutants produced and circulated within carcass and corpse burial systems.

Risk factors for endemic chronic kidney disease of unknown etiology in Sri Lanka: Retrospect of water security in the dry zone.

The prevalence of chronic kidney disease of unknown etiology (CKDu) is receiving considerable attention due to the serious threat to human health throughout the world. However, the roles of geo-socio-environmental factors in the prevalence of the CKDu endemic areas are still unknown. Sri Lanka is one of the countries most seriously affected by CKDu, where 10 out of 25 districts have been identified as the areas with the high prevalence of CKDu (10-20%). This review summarizes the geographical distribution of CKDu and its probable geochemical, behavioral, sociological, and environmental risk factors based on research related to hydrogeochemical influences on CKDu in Sri Lanka. More than 98% of CKDu patients have consumed groundwater as their primary water source in daily life, indicating the interactions of geogenic contaminants (such as F-, total dissolved solids, Hofmeister ions) in groundwater is responsible for the disease. Apart from the hydrogeochemical factors, mycotoxins, cyanotoxins, use of some herbal medicines, dehydration, and exposure to agrochemicals were alleged as risk factors. Sociological factors, including poverty, living habits and anthropogenic activities, may also provoke the emergence of CKDu. Therefore, the interaction of geo-socio environmental risk factors should be sociologically and scientifically considered to prevent the prevalence of CKDu. Future in-depth studies are required to reveal the individual role of each of the postulated etiological factors, possibly using machine learning and advanced statistics.