WHO Standards For Drinking Water Research Articles

Investigation and Evaluation of Aquiferous Zones Within Orlu and Its Environs, Using a Geo-electrical and Physiochemical Approach

This study investigated the suitability of drinking water in Orlu, Nigeria, facing challenges due to limited surface water availability and environmental deterioration. To solve the problem of the availability of portable water, electrical resistivity surveys using a Schlumberger array were conducted to identify potential groundwater resources. Twelve locations were assessed, revealing resistivity values indicative of potential aquifers. Following the geophysical survey, the physicochemical properties of water samples collected from various locations were analyzed. Parameters including pH, dissolved oxygen (DO), total dissolved solids (TDS), and minerals were evaluated against WHO and Nigerian drinking water standards. The analysis indicated generally good water quality across the sampling sites. pH levels were within the recommended range, and DO concentrations met the minimum requirements. Similarly, TDS and BOD values suggested low levels of organic matter and dissolved solids. Mineral content also remained below WHO-permissible limits. A Water Quality Index further confirmed that the water quality within the study area can be graded from good to excellent in quality. These findings suggest that the groundwater resources identified in the study hold promise for providing safe drinking water in Orlu and its environs.

Phytic acid-functionalized polyamidoxime/alginate hydrogel for targeted uranium extraction from acidic wastewater

Efficient removal of uranium from radioactive wastewater is crucial for both environmental protection and sustainable development of nuclear energy. However, selectively extracting uranium from acidic wastewater remains a significant challenge. Here we present a phytic acid-functionalized polyamidoxime/alginate hydrogel (PAG) via a facile one-step hydrothermal reaction. The PAG, leveraging the robust binding affinity of phytic acid and the selective coordination of amidoxime for U(VI), exhibited high efficiency and selectivity in adsorbing U(VI) from acidic uranium-containing wastewater. At pH 2.50, U(VI) adsorption equilibrium was achieved within 60 min, showcasing a maximum theoretical adsorption capacity of 218.34 mg/g. Additionally, the PAG demonstrated excellent reusability, maintaining a uranium removal rate exceeding 90 % over five adsorption-desorption cycles. Remarkably, the as-synthesized PAG removed 94.1 % of U(VI) from actual acidic uranium-contaminated groundwater with excellent anti-interference performance, reducing U(VI) concentration from 272.0 μg/L to 16.1 μg/L and making it meet the WHO drinking water standards (30 μg/L). The adsorption mechanism was elucidated through XPS and DFT calculation, revealing that the uranyl ion primarily coordinated with phosphate and amidoxime groups on phytic acid and polyamidoxime, respectively. These findings underscore the promising potential of PAG hydrogel for addressing acidic uranium-containing wastewater from uranium mining and metallurgy.

Water quality assessment, possible origins and health risks of toxic metal(loid)s in five cascade reservoirs in the upper Mekong

The Mekong River holds significant importance as a transnational water system within the Asian region. This study investigated the pollution characteristics, origins, and health risks associated with eighteen toxic metal (loid)s (TMs) across various depths in five cascade reservoirs located in the upper Mekong. The findings revealed that naturally sourced TMs (As, Cd, Li, Mo, Sb, and Sr) exhibited elevated levels in upstream reservoirs due to the interception effects of cascade dams. Anthropogenically sourced TMs (Co, Cu, Ni, Pb, and Zn) showed heightened concentrations in downstream reservoirs, linked to increased human activities in the downstream region. In deep-water reservoirs, the vertical distribution of redox-sensitive elements was influenced by thermal stratification, with concentrations of As, Cs, Li, Mo, Rb, Sr, and U notably higher in the hypolimnion than the epilimnion. Importantly, the concentrations of all elements in these cascade reservoirs meet Chinese and WHO drinking water standards. Water quality index (WQI: 9.2–19.1), heavy metal evaluation index (HEI: 0.96–1.37), and Nemerow index (NI: 0.35–0.56) confirmed the commendable quality of the cascade reservoir waters. The health risk assessment identified As, Sb, U, and Tl as primary contributors to non-carcinogenic risks in the cascade reservoirs. In the context of a series of cascade dams along this substantial river, this research establishes a solid foundation for preventing TM pollution and ensuring the long-term sustainability of water resources.

Ultra-selective uranium separation by in-situ formation of π-f conjugated 2D uranium-organic framework

With the rapid development of nuclear energy, problems with uranium supply chain and nuclear waste accumulation have motivated researchers to improve uranium separation methods. Here we show a paradigm for such goal based on the in-situ formation of π-f conjugated two-dimensional uranium-organic framework. After screening five π-conjugated organic ligands, we find that 1,3,5-triformylphloroglucinol would be the best one to construct uranium-organic framework, thus resulting in 100% uranium removal from both high and low concentration with the residual concentration far below the WHO drinking water standard (15 ppb), and 97% uranium capture from natural seawater (3.3 ppb) with a record uptake efficiency of 0.64 mg·g−1·d−1. We also find that 1,3,5-triformylphloroglucinol can overcome the ion-interference issue such as the presence of massive interference ions or a 21-ions mixed solution. Our finds confirm the superiority of our separation approach over established ones, and will provide a fundamental molecule design for separation upon metal-organic framework chemistry.

Multiple stable isotopes and geochemical approaches to elucidate groundwater reactive transport paths in mining cities: A case from the northern Anhui, China

Mining cities are ecotone areas where human and natural components interact. Indeed, the negative effects of mining activities on drinking water quality have become a serious public concern worldwide. To elucidate groundwater genesis and reactive transport path controlling the water pollution, a multi-bodies system in the Sunan Mine area in China was considered in this study. The results of the mineral phase characterizations, hydrochemical analysis, and multiple stable isotopes (δ2H/δ18O, δ34S and 87Sr/86Sr) indicated that calcite, dolomite, gypsum, quartz, halite, organic carbon, and gases (O2, CO2 and H2O) were the primary reactants in the aquifer system, accompanied by dissolution and precipitation of minerals, cation exchange, desulfation, and evaporation. An inverse hydrogeochemical model was employed to identify three paths, Path 1 demonstrated that mine water mainly originated from the Quaternary loose aquifer water (QLA), Permian fractured sandstone aquifer water (PFA), and Carbonifer fractured limestone aquifer water (CFA), accompanied by high K++Na+ and HCO3− concentrations due to the carbonate dissolution, halite dissolution, and cation exchange processes. Path 2 showed that the recharge of the CFA and Ordovician fractured limestone aquifer (OFA) occurred from the shallow recharge zone to the deeper OFA water through faults and fractures, mainly involving halite dissolution, carbonate dissolution, and gypsum dissolution. Path 3 demonstrated the interaction between the Hui River, collapsed pond water, and QLA, accompanied by gypsum dissolution, calcite dissolution, and cation exchange. Although the shallow QLA quality met the WHO drinking water standards, the pollution risk from the surface collapse pit water cannot be ignored. Therefore, effective approaches need to be considered in the study area to reduce the connection between the collapse pit water and QLA. The study results can help decision makers to predict water quality of complex water systems in ecotone areas and other similar regions worldwide.

Assessment of Bacteriological Contamination of Hand-Dug Wells in Rural and Urban Areas in Ondo State, Nigeria

The study analysed the total bacteria, total coliform and Escherichia coli (E. coli) concentrations of ten randomly selected hand-dug groundwater wells: five each from Alagbaka (Urban area) and another five from Ijare communities (Rural area) in Ondo State. Collins and Lyne’s pour plate method was used for the laboratory analysis. The laboratory results showed that 30%, 90% and 0% of the groundwater samples were above the WHO drinking water standards for total bacteria, total coliform and E. coli, respectively. Furthermore, the groundwater samples collected in the urban study area had total bacterial and total coliform mean levels of 24 and 15 cfu/100mL respectively compared to those of the rural study area with mean concentrations of 15 and 5 cfu/100mL, respectively. There was however no E. coli in the groundwater of both areas studies indicating the absence of faecal contamination in groundwater. It can therefore be concluded that there is a higher risk of microbial contamination of groundwater in urban land use than in rural land use and that groundwater in the study areas is unsafe for consumption unless it is first treated with appropriate treatment methods. For future research, the contamination level of other micro-organisms such as fungi, viruses, protozoa etc. should be assessed in study areas, as well the sources of microbial contamination in groundwater.

Rapid and selective removal of trace As(III) from water using Fe[sbnd]Mn binary oxide

The rapid removal of trace arsenic is crucial for ensuring the safety of drinking water. However, achieving the rapid removal of trace arsenic poses a significant challenge. In this study, we aim to enhance the removal efficiency of trace arsenic by increasing the specific surface area of the adsorbent material while maintaining its micrometer size. The material design allowed for the rapid removal of trace amounts of As(III) in groundwater within 10 s, resulting in a concentration as low as 0.281 μg L−1, which meets the WHO drinking water standard (<10 μg L−1). Our experimental results demonstrated that the FeMn binary oxide could partially oxidize As(III) into As(V), achieving a removal efficiency exceeding 99 %. Furthermore, we investigated the influence of common cations and anions, such as K+, Mg2+, Ca2+, Cl−, NO3−, SO42−, and PO43−, which may be present in natural water, on As(III) removal. Our findings indicated that the FeMn binary oxide exhibited remarkably high separation factors (ranging from 10 to 103) for other coexisting ions, indicating its exceptional selectivity for As(III) even in the presence of other ions. The outstanding arsenic uptake capability and selectivity of the FeMn binary oxide make it a highly promising adsorbent for the efficient removal of trace As(III) from aqueous solutions.

Organic-Inorganic hybrid membrane for simultaneous heavy metal removal at drinking water pollution concentration levels

This study proposes a novel approach for simultaneous removal of potentially toxic metals from contaminated drinking water. The strategy is based on multi-layer graphene oxide hybrid membranes made up of Fe3O4@amyloid fibrils nanoclusters intercalated into the graphene oxide sheets via flow through approach. The hybrid membrane outperforms the previously known graphene-based membranes with adsorption capacity in the range of 128–570 mg g−1 of material. The membrane's removal efficacy exceeds 99.9% in both low (150 µg/L) and high (10,000 µg/L) metal concentration regimes, representative of ground water and wastewater contamination and complies with WHO drinking water requirements. Following NSF/ANSI 42,53–2007a American Standard Regulations, samples with metal concentrations of 150 µg/L and 20 mg L−1 calcium coexisted at pH 6.5 ± 0.25, complete removal of heavy metals (100%) in the effluent was observed. Benchmark testing on real municipal and ground water samples in continuous operation mode shows that ∼ 7500 and 5000 L water/g of membrane were treated well while maintaining WHO drinking water standards. The saturated membrane regenerated and successfully reused several times without losing purification performance. The present technique shows a great deal for addressing the worldwide problem of contaminated drinking water due to good selectivity, low fabrication cost, and excellent performance on real water.

Risk assessment of Sanitation and water Infrastructure in informal settlements of Kisumu: Implications for Hygiene and Public Health

Risk assessment encompasses assessment and reporting of the potential harm, danger and health concerns arising from the use or contact with potentially harmful materials or substance. In the context of urban sanitation and water, risk assessment may involve the assessment of the likely harm arising from the use of unprotected or unimproved water and sanitation facilities and likelihood of injuries that such facilities may exert on the community. Urban informal settlements, which remain the face of urban vulnerability in most developing countries, are dominated by unprotected sanitation facilities and water sources which have subsequently exacerbated the urban social and health vulnerabilities and risks. This article assessed risks from sanitation and water infrastructure in urban informal settlements and their implications on community hygiene and public health using the case study from Kisumu City, Kenya. The article is based on data collected using a modified WASHFIT risk assessment tool developed by the WHO. One hundred and fourteen water sources and 460 sanitation facilities were covered by the study. Findings from the study revealed that 87% of water sources studied were shared by multiple households, while 65% and were unprotected. Some improvements had been undertaken in only less than 20% of sanitation facilities, with large proportion accounting for the ventilated improved pit latrine type. The remaining more than one fifth or 80% of the facilities were poorly constructed traditional pit latrines. Water quality findings revealed that nitrate and thermotolerant coliform levels were higher across most water sources and beyond the minimum recommended thresholds by WHO drinking water standards. On the risk assessment scale, 67% of water sources and 70% sanitation facilities were categorised as “risky” respectively.

Silver (Ag) based nanoparticles in paraffin wax as thermal energy storage for stepped solar still – An experimental approach

Paraffin wax is used as a phase change material for thermal energy storage using silver (Ag) nanoparticles doped at different concentrations. The characteristics of Ag nanoparticles in terms of microstructural and thermal analysis are made to study the surface morphology of the nanoparticles. The weight composition of Ag nanoparticles in the paraffin wax is varied between 1 and 2%, and the comparison of thermal characteristics such as thermal conductivity (TC), Differential scanning calorimetry (DSC), and Thermogravimetric analysis (TGA) is made with respect to paraffin wax (PW) without nanoparticle. From the results of thermal conductivity, it is found that the relative improvement in thermal conductivity is found as 1.25 times using 2% of silver nanoparticle in paraffin wax as compared to the PW without NP’s. The DSC results revealed that the temperature of melting using 2% Ag NP’s 57.3 °C, as compared to PW without NP’s. Similarly, experiments are conducted on the stepped basin SS with Ag nanoparticle-based PW as thermal energy storage, and the thermal performance and palatable water generation are compared with SS using PW as thermal energy storage and without PW. The results indicated that with the use of nano-enhanced PW as heat energy storage in the basin of stepped SS, the water temperature, evaporation rate, and accumulated palatable water generation enhanced. The total palatable water generated from the SS using Ag nanoparticles in PW, PW without nano additive, and SS without PW is found as 7.98, 6.73, and 3.61 kg/m2, respectively. The relative improvement in the palatable water generation using Ag nanoparticle doped PW than pure paraffin wax which is due to the change in thermophysical properties, improved heat transport phenomenon, which improved the night time palatable water yield with higher retention of heat dissipated to the water through the basin. The economic analysis showed that the cost of producing potable water from the stepped SS by utilizing Ag-doped paraffin wax rose to 0.019 $ per litre, while the cost of producing potable water from the SS that used paraffin wax as thermal energy storage and SS without any thermal energy storage was determined to be 0.017 $ per litre and 0.018 $ per litre, respectively. However, the yearly palatable water generated from the SS employing the suggested modification is enhanced by about 18.42% and 120.72% in comparison to the SS with thermal energy storage and the SS without thermal energy storage, respectively. The results of the water quality investigation showed that the pH, TDS, thermal conductivity, and total hardness limitations of the consumable water generated by the thermal-based desalination system are within the limits of ISO 10500–2012 and WHO drinking water standards.

Microbial biochemical pathways of arsenic biotransformation and their application for bioremediation.

Arsenic is a ubiquitous toxic metalloid, the concentration of which is beyond WHO safe drinking water standards in many areas of the world, owing to many natural and anthropogenic activities. Long-term exposure to arsenic proves lethal for plants, humans, animals, and even microbial communities in the environment. Various sustainable strategies have been developed to mitigate the harmful effects of arsenic which include several chemical and physical methods, however, bioremediation has proved to be an eco-friendly and inexpensive technique with promising results. Many microbes and plant species are known for arsenic biotransformation and detoxification. Arsenic bioremediation involves different pathways such as uptake, accumulation, reduction, oxidation, methylation, and demethylation. Each of these pathways has a certain set of genes and proteins to carry out the mechanism of arsenic biotransformation. Based on these mechanisms, various studies have been conducted for arsenic detoxification and removal. Genes specific for these pathways have also been cloned in several microorganisms to enhance arsenic bioremediation. This review discusses different biochemical pathways and the associated genes which play important roles in arsenic redox reactions, resistance, methylation/demethylation, and accumulation. Based on these mechanisms, new methods can be developed for effective arsenic bioremediation.

Effects of Household Waste Disposal on Surface and Ground Waters in the Rapidly Urbanising Mamfe Town (South-West Region, Cameroon)

Huge waste generation by the rapidly growing Mamfe town is posing enormous environmental challenges. This work that aimed at examining the implications of household waste on potable water sources, used the mixed research design, combining descriptive and experimental approaches. Ground (Two wells, one borehole) and surface (two streams) sources were sampled and empirical data for physicochemical parameters (PH, EC, water temperature, TDS, and salinity) of the five water samples were measured in-situ using a multi-meter and complemented by questionnaires and interviews information. Data obtained were analysed using the One-way ANOVA and chi-square tests. Except for the pH, values of 11 of the 12 physical and chemical elements (Temperature, EC, TDS, pH, Ca32+, Mg2+, Na+, K+, HCO3-, Cl-, NO3 -) were within permissible limits of WHO drinking water standard. Hierarchical cluster analysis revealed two clusters: EC and TDS; and temperature (?), pH, Ca2+, Mg2+, Na+, K+, HCO3-, Cl-, NO3-, and salinity. Spearman correlation analysis for minor parameters as Temperature, EC, TDS and Cl- and major parameters of Ca2+, Mg2+, Na+, K+ and HCO3,reveals a strong positive correlation between HCO3- and Ca2+, temperature and NO3-. Therefore, municipal authorities are entreated to implement sustainable waste and water management strategies.

Hydrochemical characteristics, quality and health risk assessment of nitrate enriched coastal groundwater in northern China

Groundwater quality is an essential factor restricting regional sustainable development owing to water resource scarcity, especially in coastal regions. Coastal groundwater is affected by natural conditions and strong human activities, and the evolution of water quality is extremely complex. Information on the hydrochemistry evolution and nitrate contamination status of coastal groundwater under the conjunctive effects of natural processes and human activities is a vital requirement for groundwater resource management in coastal regions. Thus, this study integrated traditional hydrochemical analysis approaches, the entropy-weight water quality index (EWQI), and the health risk assessment model to analyze hydrochemical characteristics, quality, and nitrate health risks in a typical coastal region (i.e., southern Laizhou Bay) simultaneously affected by seawater intrusion and anthropogenic activities, as well as to explore the dominant mechanisms controlling groundwater quality. The results indicated that the concentrations of major hydrochemical constituents in groundwater exhibited wide variability. The NO3− concentration varied from 0.59 to 824.80 mg/L; it surpassed the WHO drinking water standard (50 mg/L) at 89.47% of sampling sites. The predominant hydrochemical types of groundwater were SO4•Cl–Ca•Mg and HCO3–Ca•Mg. Governing factors influencing groundwater chemistry were recognized as rock weathering, inverse cation exchange and anthropogenic activities, and nitrate contents were largely controlled by agricultural practices. The computed EWQI showed that 55.26% of groundwater samples possessed EWQI values greater than 57, which is relatively poor-quality groundwater. The poor-quality groundwater was concentrated in the southwestern part of the study area. Non-cancer risks of nitrate in 96.71%, 94.74%, 89.47%, and 89.47% of the groundwater samples were unacceptable for infants, children, teens, and adults, and the spatial distribution of the hazard quotient (HQ) was in accordance with the spatial pattern of nitrate concentration. These findings can guide the exploitation and utilization of groundwater resources and water quality conservation in coastal regions.

Preparation of carbon quantum dots from ionic liquid modified biomass for the detection of Fe3+ and Pd2+ in environmental water

A new type of green carbon quantum dots (ILB-CQDs) was prepared by hydrothermal method using ionic liquid as a modifier and grape skin as carbon source, and was obtained from hydrogen-bonded lattice structure ionic liquid preparation, which makes the CQDs in a ring-like stable structure with a stability period of more than 90 day. There is also the catalytic effect of the ionic liquid on cellulose, which makes the prepared CQDs show good advantages, such as uniform particle size, high quantum yield (26.7%), and very good fluorescence performance. This is a smart material for the selective detection of Fe3+ and Pd2+. It has a detection limit of 0.001 nM for Fe3+ and 0.23 µM for Pd2+ in pure water. It has a detection limit of 3.2 nmol/L for Fe3+ and 0.36 µmol/L for Pd2+ in actual water, both of which meet the requirements of WHO drinking water standards. And there is to achieve more than 90% of water restoration effect.

Effective biosorption of As(V) from polluted water using Fe(III)-modified Pomelo (Citrus maxima) peel: A batch, column, and thermodynamic study

Pomelo, Citrus maxima, peel was chemically modified with lime water and then loaded with Fe(III) to develop anion exchange sites for effective sequestration of As(V) from water. Biosorbent characterizations were done by using FTIR, SEM, XRD, EDX, and Boehm's titration. The batch biosorption studies were carried out at various pHs using modified and non-modified biosorbents and optimum biosorption of As(V) occurred at acidic pH (3.0–5.0) for both the biosorbents. A kinetic study showed a fast biosorption rate and obtained results fitted well with the pseudo-second-order (PSO) model. When isotherm data were modeled using the Langmuir and Freundlich isotherm models, the Langmuir isotherm model fit the data better and produced maximal As(V) biosorption capacities of 0.72 ± 03, 0.86 ± 06, and 0.95 ± 05 mmol/g at temperatures 293± 1K, 298± 1K and 303± 1K, respectively. Desorptionof As(V) was effective using 0.1 M NaOH in batch mode. Negative values of ΔG° for all temperatures with positive ΔH° confirmed the spontaneous and endothermic nature of As(V) biosorption. The existence of co-existing chloride (Cl−), nitrate (NO3−), sodium (Na+), and calcium (Ca2+) showed insignificant interference whereas a high concentration of sulphate (SO42−) and phosphate (PO43−) significantly lowered As(V) biosorption percentage. Arsenic concentrations in actual arsenic polluted groundwater could be reduced to the WHO drinking water standard (10 μg/L) by using only 1 g/L of investigated Fe(III)-SPP. The dynamic biosorption of As(V) in a fixed bed system showed that Fe(III)-SPP was effective also in continuous mode and different design parameters for fixed bed system were determined using Thomas, Adams-Bohart, BDST, and Yoon-Nelson models. Therefore, from all of these results it is suggested that Fe(III)-SPP investigated in this study can be a potential, low cost and environmentally benign biosorbent material for an effective removal of trace amounts of arsenic from polluted water.

Optimization of preparation parameters of ceramic pot water filters for potential application of microbial and fluoride removal from groundwater

The need to make clean water accessible and affordable for low-income countries is crucial. This study examines the suitability of various clays for Ceramic Pot Water Filters production and groundwater treatment for effective microbe and fluoride removal. For this study, three clays were collected from different geographical locations in Ethiopia,i.e., Hosaenna Clay, Babawuha Clay, and Leku Clay. Organic additives such as sawdust and eragrostis tef husks were used to increase the porosity of the Ceramic Pot Water Filters. The Atterberg limit and particle size distribution tests revealed that BC and HC have moderate to high plasticity and mouldability, making them suitable for CPWF production. The clay chemical composition, phase analysis, and thermal properties were determined using XRF, XRD, and TGA/DTA. The turbidity, fluoride level, total dissolved solids, and pH of the groundwater decreases, from 13 to 0.45 NTU, from 3.4 to 0.053 mg/100 mL, from 1245 to 360 mg/l, and from 8.4 to 7.3, respectively; all of which are within the acceptable range of WHO drinking water standards. Microbial removal tests show that the CPWFs removed 99.3%–100% of total coliform bacteria and 98.48%–100% of fecal coliform bacteria from groundwater. Therefore, this work paves the way to fabricate a clay-based ceramic water filter for low-income countries to provide affordable household groundwater treatment technology for microbial and excess fluoride removal.

A Novel Whole-Cell Biosensor for Bioavailable Antimonite in Water and Sediments.

Antimony (Sb) is an emerging contaminant, and its on-site speciation analysis is central to the accurate evaluation of its bioavailability and toxicity. The whole-cell biosensors (WCBs) for Sb(III) are promising but challenging due to the lack of Sb(III)-specific recognition components. Here, we constructed a novel Sb(III)-specific WCB using an Sb(III) transcriptional regulator (antR) and its cognate promoter (Pant). To prevent the promoter leakage of Pant, an additional regulatory gene, antR, was inserted downstream of the Sb(III)-inducible promoter, improving the sensitivity of the WCB by an order of magnitude and reaching the detection limit at 0.009 μM, which is lower than the WHO drinking water standard of Sb. Moreover, the WCB with double antR showed a high specificity toward Sb(III) compared with interfering ions at 3 orders of magnitude higher concentrations. This WCB was capable of measuring Sb(III) bioavailability in natural waters and sediments on-site, and its results were not statistically different from the chemical analysis. The insights gained from this work demonstrate that the addition of regulatory genes prevents promoter leakage and improves the sensitivity of WCBs in field applications. IMPORTANCE Antimony (Sb) is a redox-sensitive pollutant ubiquitous in the environment. Sb(III) is dominant in the subsurface and is readily oxidized to less toxic Sb(V) upon exposure to air, and therefore, on-site Sb speciation analysis is essential to evaluate its bioavailability and toxicity. Dissolved Sb concentration and speciation can be determined accurately using on-site chemical sensors, but chemical sensors have difficulty determining the bioavailable Sb(III) that is taken up by the cells. Here, we constructed an Sb(III)-specific whole-cell biosensor (WCB) using double Sb(III) transcriptional regulators (antR) downstream of its cognate promoter Pant. With an additional antR, the sensitivity of the WCB was improved by approximately 10 times, and the promoter leakage commonly found in WCBs was inhibited. Integrated with a tea-bag design, the WCB is able to measure Sb(III) bioavailability in natural water and sediments on-site. This study demonstrates the importance of inserting one more regulatory gene to improve sensitivity.

Using Strychnos potatorum Seeds as a Natural Coagulant in Flood Affected Areas of Bangladesh

The aim of this research is to find and show the effectiveness of Strychnos potatorum seeds as a natural coagulant for purifying and producing potable water in flood prone rural areas of Bangladesh. Strychnos potatorum, locally called ‘Nirmali’ or ‘Nirmala’, is a natural coagulant which was used in the Indian Subcontinent during the stone ages but has slowly become forgotten. This research was carried out to reintroduce this ancient coagulant and find its effectiveness during floods, particularly in Bangladesh. As a riverine country prone to flooding and devoid of quality water purification systems, coagulants like alum and ferric sulfates are often used although these synthetic chemicals have been found producing DBPs in water which are associated with certain health hazards. And so, replacing these synthetic chemicals with a natural coagulant such as Strychnos potatorum seeds in flood prone rural areas will be a beneficial and cheap water purification system for the populace. To prove the effectiveness, various tests (pH, HCO3 , Cl, Na, K, Na2 CO3 , NTU, TCU, Total Hardness (CaCO3 ), BOD, COD, CFU) were carried out across flood prone areas around Dhaleshwari River (Nagarpur, Tangail) to find out whether Strychnos potatorum seeds will be able to replace the commonly used chemical coagulants and provide drinkable water to the flood affected people or not. Experiments were carried out to find the optimal dosage, flocculation and settling time and reusability of the Strychnos potatorum seeds. The reason behind selecting this region for research purpose is that the soil and tree characteristics of this area is perfect for planting and growing Strychnos potatorum trees and they can be easily distributed among the populace when disaster hits. The test results proved that the parameters comply with the WHO Drinking Water Standards. So, our test results have shown that the Strychnos potatorum seeds are highly effective when it is used to treat water in these flood prone areas. And our initial estimation is Strychnos potatorum will provide a remarkably successful and high yield in these targeted areas. According to our calculations and research it will cost only 0.18 dollars or 18 cents versus 0.25 dollars for most conventional method (Potash Alum) for per liter of water treatment. As the project will require planting Strychnos potatorum trees, the project will improve the environment and distributing them to flood affected populace will increase the peoples’ awareness regarding tree plantation and drinking safe water. Also, this project will act as a replacement to the synthetic chemical coagulants used in the flood affected rural areas of Bangladesh and replacing those synthetic chemical coagulants with biodegradable Strychnos potatorum will be good for the environment as a whole there will be less chemical waste. This project will strengthen the water security of Bangladesh as well as play an important role in stopping the climate change and its adversities.

Potentially toxic elements in groundwater of the upper Brahmaputra floodplains of Assam, India: water quality and health risk.

This paper presents the groundwater quality assessment of the upper Brahmaputra floodplains of Assam on a seasonal basis. A total of 88 samples were analyzed for the presence of potentially toxic elements in two seasons. In addition, an attempt is made to identify any possible associated health risks to the residents via the drinking water pathway. The study reveals the presence of various potentially toxic elements, in particular, manganese, iron, nickel, and fluoride concentration exceeding the drinking water specifications set by BIS and WHO drinking water standards. The degree of groundwater contamination was assessed using the Water Quality Index, Heavy metal Pollution Index, Heavy metal Evaluation Index, and Degree of Contamination. The spatial distribution maps of groundwater quality were prepared using geographical information system. The non-carcinogenic health risk was evaluated using hazard quotients and hazard index as per the United States Environmental Protection Agency methodology. The hazard quotient of fluoride and manganese have values > 1, which exceeds USEPA recommended benchmark. The health risk assessment identified that the risk was highest during the pre-monsoon season, and the child population is more vulnerable to non-carcinogenic risk than the adults. Findings of cancer risk identified that pre-monsoon groundwater samples from the Golaghat District pose the highest health risks in the upper Brahmaputra floodplains. The risk is highest in the southwest of the study area, followed by the south and then by the north.

Drinking water quality assessment according to water quality index and health risk assessment: а case study of Pedro Vicente Maldonado canton, Ecuador

The effluent water quality of a treatment plant in a canton of Ecuador according to water quality index (WQI) and health risk assessment was investigated in this study. The quality of the influent and effluent water of the treatment plant was monitored monthly from January 2017 to December 2019. Physicochemical and microbiological parameters, such as temperature, pH, turbidity, color, suspended solids, electrical conductivity, free chlorine, nitrates, nitrites, ammonia nitrogen, sulfates, fluorides, manganese, iron, fecal coliforms and total coliforms were determined. To evaluate the impacts of studied water on human health, health risk assessment for non-cancerogenic elements, including hazard index (HI) and risk of olfactory-reflex effects for organoleptic indicators were performed in accordance with Russian and foreign guidelines. Water quality parameter results were compared with WHO drinking water standards, revealing that the influent was contaminated microbiologically and other parameters such as color, turbidity, and iron were also above the limit values. The WQI results showed that water after purification is suitable for drinking (I class - excellent). Hazard Index (HI) results showed that the non-carcinogenic substances studied had a low risk for both adults and children (1). Additionally, the risk of olfactory-reflex effect was characterized as acceptable for all the collected purified water samples.