Technology alternatives for decontamination of arsenic-rich groundwater—A critical review

Abstract

Abstract Arsenic (As) contamination of groundwater is being reckoned as a global problem, as over 296 million people residing in more than 100 countries have already been reported to be affected by arsenic-rich groundwater. Developing countries like Bangladesh, India, Thailand, Taiwan and Vietnam are the worst victims of this terrible event. Arsenic naturally exists in more than 320 mineral forms mainly as arsenates, sulfides, sulfo-salts, arsenides, arsenites, oxides, silicates and elemental arsenic. The lifetime cancer risk of arsenic at its Maximum Contaminant Level (MCL of 10 μ g/L) is estimated at 0.7 in 100, while for other carcinogens, it ranges from ( ∼ 0.001 to 0.012) in 100. Water, besides food, is the main source of arsenic ingress into the human system. Both groundwater and surface water are being found contaminated with arsenic due to natural and anthropogenic activities respectively Over the years, various physico-chemical and biological methods viz. oxidation, coagulation–flocculation, adsorption, biological sorption, ion-exchange, membrane processes, treatment with bio-organism and electrocoagulation have been profusely experimented and reported by different researchers for arsenic remediation from the groundwater. In this paper, various technologies available for arsenic remediation, their removal mechanisms, cost-effectiveness and sustainability have been reviewed in a critical and rigorous manner. Attempts have also been made to point out the advantages and drawbacks of different methodologies and future research needs in the sphere of arsenic remediation from groundwater.