14. A Critical Review of Various Arsenic and Iron Removal Plants Installed in North 24 Parganas District of West Bengal, India

India and Bangladesh are the major countries affected by arsenic contamination in groundwater. These countries in collaboration with the various national and international organizations have installed Arsenic and Iron Removal Plants (AIRPs) with different technologies to mitigate this problem. This study was conducted on four numbers of distinguished technologies installed in the North 24 Parganas district of West Bengal, India. This paper studied the performances of these AIRPs and statistical analysis is performed to compare among them. The Raw water arsenic concentration among the four AIRPs ranges between 22 and 400 µg/l and the Iron concentration lies between 510 and 4230 µg/l. Among the technologies, T1 seems to be the most efficient technology in removing arsenic with a mean of 98.25% overall arsenic removal efficiency with a standard deviation of 1.04%. The T3 technology seems another efficient technology with a mean overall removal efficiency of 91.46% but in the last few months a problem of backwashing affects the treated water quality and arsenic concentration found more than the acceptable limit as per WHO and BIS guideline. The other T2 and T4 technology were not so efficient in maintaining the arsenic and Iron level below the permissible limit constantly. There are plenty of operation and maintenance-related issue was found during the field visit and a critical review and percussion measurement also been made to improve the performance of the AIRPs.