Contamination of groundwater by arsenic: a review of occurrence, causes, impacts, remedies and membrane-based purification

The contamination of groundwater by leached out arsenic has assumed an alarming proportion in several countries. Continued and prolonged ingestion even at a very low level can lead to serious arsenic-related diseases. Strong epidemiological evidence of arsenic carcinogenicity has forced the World Health Organization (WHO) to lower the maximum permissible contaminant limit (MCL) in drinking water to 10 ppb from earlier limit of 50 ppb. This has thrown a big challenge to the scientific community to devise efficient methods to purify contaminated water to such a high level. Though literature abounds in occurrence of groundwater contamination by arsenic and its removal from drinking water by laboratory techniques, millions of people continue to suffer, particularly in the developing countries like India (Bangladesh, West Bengal). Through a comprehensive review of the existing literature on the occurrence, causes, impacts and remedial measures, this article finds out what has gone wrong and what is to be done with special emphasis on membrane-based separation that seems to be highly promising in purifying arsenic-contaminated groundwater to a WHO-prescribed level.