Groundwater for drinking and industrial purposes: A study of water stability and human health risk assessment from black sand mineral rich coastal region of Kerala, India.

Tempero-spatial analysis of groundwater to disseminate the level of drinking water quality and industrial suitability to meet the developmental requirement of a region is a significant area of research. Accordingly, groundwater quality and geochemical interactions prevailed in a black sand mineral rich coastal village is systematically presented in appraisal of drinking and industrial uses for economic engineering purposes. The study area focused is Alappad village, Kollam, Kerala, India has numerous ecological features in a sustainable perspective. The region is unique with placer deposits where an alluvial soil aquifer-saline water-freshwater interaction occurs. This dynamics decides the pertinent hydro geochemistry, potable and designated uses of ground water in season wise. Coastal area is hereby presented based on water quality parameters predicted with the health risk assessment model with a view on human health and cancer risk due to ions (Pb, Ni, Cu, Ba, Fe, Al, Mn, Zn) in groundwater.. To ascertain industrial usage, ground water is evaluated by Langelier saturation index (LSI), Ryznar stability index (RSI), Aggressive index (AI), Larson-Skold index (LS) and Puckorius scaling index (PSI) and inferences are complemented. Chemical weathering and evaporation processes are the natural factors controlling hydrochemistry of this aquifer. This complex coastal system has Nemerow pollution index (NPI) of moderate pollution for total dissolved ions of Fe and lesser for Cu, and Cr present in groundwater. LSI indicates, water is scale forming but non corrosive (46% in PRM, 20% in MON and 47% in POM). Water quality index (WQI) in POM (ranged 28.7-79.9) was excellent for drinking, followed by PRM (23.6-218.2) and MON (33.4-202.7) seasons. This groundwater bears temporary hardness with the dominance of Ca-Mg-HCO3 water type. Health risk assessment of non-carcinogenic risk index of trace metals (Fe, Zn, Mn, and Pb) revealed, children are at 'low risk' and 'medium' risk with Ni and Cu. The carcinogenic risk index indicated 93% of samples were high Ni induced cancer risk for children, and 87% for adults due to long term ingestion (drinking water intake) pathway. Studies specific on placer mineral deposited coastal region of India are not sufficiently reported with a focus on the above perspectives. Growing need of rare earths for material, device and energy applications, placer mineral explorations can destabilise the coastal hydrosphere. Interrelations of mineral soil - water chemistry prevailed and health hazard predicted would kindle a set of sustainable deliberations. This study summarises the drinking and industrial use of coastal groundwater for future development and human well-being on the basis of quality criteria, corrosion proneness, water stability and health risk factors.

Groundwater chemistry and entropy weighted water quality index of tsunami affected and ecologically sensitive coastal region of India.

Quality groundwater is the most essential prerequisite for the better livelihood of the coastal villages and a vital resource for a safe living. Seawater interaction and coastal inundation modify hydro geochemical cycles leading to gross utility as a challenge. Poor quality water intake causes diseases and seriously affects human health. In this study, the suitability of shallow drinking water sources (10-15 m) has been studied with a focus on coastal village in south west of India (Alappad coast, Kollam, Kerala) which is a host of huge placer mineral reserve of the country. This coastal stretch has good deposition of Late Quaternary sediments of heavy mineral placers subjected to severe seawater interactions. Mineralogically, garnet and heavy minerals comprises the beaches and most coastal plains of the Alappad. A concerted geological process where moving water and waves causes erosion, leads to lowering of the earth's surface -is prominent in this fragmented land. This study critically evaluates the temporal-spatial impact of these interactions in an age of varying climatic conditions and hence for reference beyond. Water quality index analysis has been attempted using the entropy weighted water quality index (EWQI) method for a total of 45 samples (15 samples season-wise). It aims to ascertain better choices of groundwater sources for domestic uses for isolated settlers endowed with estuaries, and old coastal plains with barrier beaches. Irrigation suitability was evaluated using sodium adsorption ratio (SAR) and Na%. Observed EWQ Indices (38.2 ± 14.5) for post-monsoon (80% samples), (66.1 ± 77.7) for monsoon (66% samples), and (71.4 ± 71.3) for pre-monsoon (53% samples) fall in excellent category. Post-monsoon is most favoured for a better quality groundwater as evidenced by WQI of 80% among the samples tested. Ca-HCO3 is the dominant hydrochemical type observed. The mean value of iron (0.9 ± 1.3 mg/L) exceeded the permissible limit of 0.3 mg/L during monsoon season due to mineral-water interactions. In pre-monsoon season the parameters Na+ (95.9 ± 200.7 mg/L), Cl- (173.4 ± 510.2 mg/L), EC (1559.3 ± 2510.6 µS/cm), and TDS (492.5 ± 629.7 mg/L) were observed in higher ranges. Significant correlation (p < 0.05) prevailed between EWQI, and parameters-conductivity (0.75), TDS (0.75), Iron (0.59), Ca2+ (0.66), and Mg2+ (0.74). Principal component analysis (PCA) on chemical parameters accounted for the total variance of 84.2% in pre-monsoon, 89.9% in monsoon and 82.9% in post-monsoon. Groundwater quality is influenced by geochemical processes, salt intrusion, and human activities like fertiliser application and domestic sewage discharge. Hierarchical cluster analysis (HCA) grouped the samples into three clusters. Cluster 3 represents poor quality water (13%) in pre-monsoon (EWQI ranged 32.2-192.7), and monsoon (EWQI ranged 171.8-309.7). Cluster 3 in post-monsoon (20%) indicating good water quality (EWQI ranged 51.4-72.6). Ultimate finding is that post-monsoon groundwater is more suitable for drinking and domestic purposes for the selected coastal area.

Integration of coagulation-flocculation and heterogeneous photocatalysis for the treatment of pulp and paper mill effluent.

A two-step process involving coagulation-flocculation followed by solar photocatalysis - based Advanced Oxidation Process (AOP) using TiO2-Reduced Graphene Oxide (TRGO) nanocomposite as catalyst has been employed for the treatment of pulp and paper mill effluent. As the effluent is loaded with a high amount of organics with initial chemical oxygen demand (COD) as high as 3516, a pre-treatment is required before applying photocatalytic treatment. Coagulation-flocculation was identified as an effective pre-treatment strategy. Among the various coagulants tested, CuSO4.5H2O showed the best % COD reduction of 84 at pH 6, at a loading of 5 g/L. The primary treatment of coagulation improved the biodegradability index from 0.23 to 0.37. TRGO photocatalyst, employed in the second stage of photocatalytic treatment was synthesised by an ultrasound assisted solvothermal method and well characterised by various spectroscopic/analytical tools. The composite was found to be an efficient solar photocatalyst and achieved 1.76 and 2.1 times more COD reduction than synthesised TiO2 and commercial P25 respectively. The final effluent after the combined treatment was neutral and the biochemical oxygen demand (BOD) and COD were 11.7 and 120 mg/L respectively which were below the given limit of National Environmental Quality Standards.

Integration of heterogeneous photocatalysis and persulfate based oxidation using TiO2-reduced graphene oxide for water decontamination and disinfection.

Advanced oxidation processes (AOPs) which involve the generation of highly reactive free radicals have been considered as a promising technology for the decontamination of water from chemical and bacterial pollutants. In this study, integration of two major AOPs viz., heterogeneous photocatalysis involving TiO2-reduced graphene oxide (T-RGO) nanocomposite and activated persulfate (PS) based oxidation was attempted to remove diclofenac (DCF), a frequently detected pharmaceutical contaminant in water. The enhanced visible light responsiveness of T-RGO would facilitate the use of direct sunlight as a benign and cost effective source of energy for the photocatalytic activation. By combining PS based oxidation process with T-RGO mediated photocatalysis, a DCF removal efficiency of more than 98% was achieved within 30 min. The effect of operating parameters like PS concentration and pH on DCF removal was assessed. Radical scavenging experiments indicated that apart from radical oxidation involving •OH and SO 4 · - radicals, a non-radical oxidation pathway was also taking place in the degradation. The antibacterial properties of the integrated system were also evaluated using Escherichia coli and Staphylococcus aureus as representative bacteria. The presence of PS in the photocatalytic reaction system improved the antibacterial activity of the composite against the two strains studied. Cytotoxicity of T-RGO nanocomposite was assessed using human macrophage cell lines and the results showed that the composite is biocompatible and nontoxic at the recommended dosage for water treatment in the present study.