Which one among the following methods is not effective in removing arsenic from contaminated ground water ?

Arsenic is a naturally occurring semi-metal element found in groundwater that poses significant health risks, including skin diseases and cancer [c4, t3]. Among the listed methods, boiling is not effective in removing arsenic from water [t3, t5]. In fact, boiling can slightly increase the concentration of arsenic due to the evaporation of water while the non-volatile arsenic remains [t5]. Conversely, effective treatment methods approved by environmental agencies include reverse osmosis (a membrane process), ion exchange, and coagulation-adsorption (often involving filtration) [t2, t3, t6]. Coagulation followed by filtration can achieve over 99% removal efficiency [t1]. Ion exchange and membrane processes like reverse osmosis are also highly effective but often more expensive for large-scale or rural implementation [t9, t10]. Therefore, while boiling kills biological pathogens, it fails to mitigate chemical arsenic contamination.

Sources

1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Consequences of Water Pollution > p. 37
2. [2] https://www.sciencedirect.com/science/article/abs/pii/S0043135405005415
3. [3] https://www.sciencedirect.com/science/article/pii/S2405844023014536