FIELD-SCALE ARSENIC REMEDIATION STRATEGIES FOR SUSTAINABLE SAFE DRINKING WATER SUPPLIES

Since the discovery of geogenic arsenic in South Asia in 1993, there were reports for widespread occurrence of geogenic arsenic in groundwater across the globe and many different household and community-scale mitigation options have been tested, with most showing only limited success. The major challenge is to develop a simple, cost-effective, and socially acceptable option with minimal supply chain, which users can install, operate, and maintain independently without the need of sustained funding from external actors. Different large-scale arsenic treatment strategies including adsorption units, various types of filters such as pond sand filters and filter membranes, rainwater harvesters, electrochemical units and well-switching to tube wells in arsenic-safe groundwater aquifers have been investigated in different countries. In many cases, pilot-scale remediation plants based on costly and complex technologies were abandoned due to the lack of an economically viable implementation plan and intricate maintenance. Furthermore, the use of rainwater harvesting and pond sand filters has been found to be discordant with user needs and behavior and year-round water quality is not ensured. By contrast, well-switching to arsenic-free sources by “targeting arsenic-safe aquifers”, was identified as a socially accepted option. Arsenic-safe tubewells were found to be a widely accepted option mainly because of their easy operation, reliability of high-quality, potable water, negligible maintenance, and their good fit into the pre-existing behaviors of most end-users. However, an existing challenge with this option in correlating geochemical parameters that drive arsenic mobilisation in the aquifers, which would allow the local drillers to identify aquifers with the highest likelihood of arsenic-safe water. Here we discusses many of the available large-scale arsenic mitigation strategies, their potency, and failures, and proposes future work to address current challenges facing the sustained provision of arsenic-safe drinking water.