Water purification of arsenic- contaminated drinking water via air gap membrane distillation (AGMD)

Arsenic contamination in shallow tubewell water is a serious health issue in Bangladesh and other Southeast Asian countries. Rural and remote areas in these locations continue to face tremendous challenges in providing access to affordable and safe arsenic-free drinking water. In recent years, intensive efforts have been undertaken to identify appropriate technologies for arsenic removal. This study examines one approach by investigating the application of suitable membrane technologies, specifically air gap membrane distillation (AGMD), as a promising method for small-scale, low cost deployment. The objective of this study was to test an AGMD commercial prototype (nominal capacity of 2 L/hr) with three different feedstocks: arsenic-containing groundwater (medium concentration) and arsenic-spiked tap water (medium and high concentrations). Results show that the tested AGMD prototype is capable of achieving excellent separation efficiency, as all product water samples showed arsenic levels well below WHO accepted limits (10 μg/L) even for initial concentrations over 1800 μg/L. Parametric studies with focus on variation of coolant temperature illustrate the possibility of integrating AGMD in various thermal systems.