Contemporary practices in groundwater arsenic remediation and wastewater management in West Bengal, India: a systematic review

Arsenic is a notorious carcinogen that is released into subsurface waters by virtue of natural geological and hydrological processes. Such a contaminated water has detrimental effects on human health when it is consumed for drinking. This paper is an effort to address the widely recognized public health crisis of arsenic poisoning in India's state of West Bengal. It is intended to provide an environmentally safe and financially feasible solution for arsenic mitigation that combines both ground water remediation and waste management situations. Treatment of pumped groundwater by Arsenic Treatment Units (ATUs) for providing potable water has been a major arsenic remediation measure in rural villages of West Bengal. But, backwash cleaning of these units generates hazardous sludge rich in toxic arsenic, disposal of which is an environmental concern. Through a field examination, detailed information on the prevalent sludge management practices at remote ATU sites were acquired and reviewed for their suitability. It was ascertained that wrongful dumping of sludge can be avoided by disposal on certain iron–rich sand filters, constructed in–situ using naturally available ingredients. Also, the incorporation of sludge in building materials, especially the clay–bricks, can be an emphatic option for arsenic waste management at commercial scales. This paper thus presents a comprehensive overview of ‘in–situ' and ‘ex–situ' strategies of arsenic mitigation. An ‘in-situ' management aspect utilizes iron–rich sand filters located within the premises of groundwater treatment units for recycling of arsenic-containing wastewater, followed by adsorption and concealment of residual arsenic. An alternative, hazard–free means of stabilizing toxic sludge off–site, with clay–bricks, at a brick manufacturing factory, has been proposed for the 'ex–situ' aspect. Many policy discussions around the globe do not feature arsenic–sludge disposal or stabilization as a topic. Keeping this is viewed, this review article concludes with innovative approaches to sustainable arsenic remediation and waste management in India.