Nationwide Assessment of Potential for Subsurface Arsenic Removal Technology in Bangladesh

Abstract:

Subsurface Arsenic Removal (SAR) technology consists of the injection of aerated groundwater into an anoxic aquifer, where oxygen in the injected water reacts with iron in the groundwater to form hydrous ferric oxide (HFO). Groundwater with lower arsenic (As) can be extracted because As sorbs onto the HFO. The performance of a SAR system is defined as the volume of water that can be extracted with As concentrations below the Bangladesh standard (<50 µg/L) relative to the volume of injected water. The effects of different background levels of As, Fe, P, Si (according to Bangladesh statistical percentiles), pH, alkalinity, HFO, and cation exchange capacity (CEC) on SAR performance were quantified with a PHREEQC Reactive Transport Model. A preliminary map of potentially suitable locations for SAR application is generated. SAR performance in Bangladesh ranges from 0 to 4. SAR performance decreases with increasing background levels of As, Si, HFO, and CEC, while SAR performance increases with increasing background levels of Fe, alkalinity, and the ratio of Fe over As.