Arsenic Removal Potential Using Naturally Occurring Iron In Groundwater: A Geo-Spatial Assessment Of Household Potable Drinking Water In Bangladesh

Arsenic removal from drinking water by co-precipitation with naturally occurring iron is considered a low-cost water treatment option at the household level but its efficiency depends on the concentration of iron as well as other competing phosphate and silicate salts present in water. This study utilizes the available household-level potable water quality data to estimate upazilla-wise arsenic removal efficiency applying a previously developed competitive sorption model. Assuming a neutral pH and no competing anions, for varying arsenic and iron concentration combinations in potable water, a removal efficiency ranging from 6.34% to 100% is estimated. But considering the interference of phosphate and silicate salts the maximum removal efficiency can potentially be reduced to 71.38%. Consequently, the population exposure in Bangladesh to arsenic contamination above WHO guideline value of 10 ppb, which is currently 32.59%, can only be reduced to 27.77% if interference of phosphate and silicate salts are taken into consideration. These estimates show that treatment of arsenic-contaminated water by co-precipitation with naturally occurring iron will only be marginally efficient for Bangladesh given the prevailing groundwater composition.