ఇంటర్నేషనల్ జర్నల్ ఆఫ్ వేస్ట్ రిసోర్సెస్

నైరూప్య

Can Electrochemistry Make the Worlds Water Clean? A Systematic and Comprehensive Overview

S. Vasudevan

Water the generous gift of nature is sure to become scarce unless the ever growing population is enlightened enough in handling the increasing stress and to avoid the crisis due to the expanding demand on this precious commodity. Management of water and its resources by conservation and its judicious use help to preserve the available water. Even then, whether it is from surface or underground sources, it has become impossible to obtain good quality water for human consumption. Thus, the dwindling quantity and lessening quality of water require effective steps to be taken urgently for the sustenance of the living being of today and tomorrow.
What this glass of water contains? worries one before he starts quenching his thirst. The extent of water contamination is so much and so varied that organic, inorganic and biological impurities are present in the water due to natural as well as induced reasons. The responsibility fell on the scientists and engineers to provide appropriate technologies help not only to remove the contaminants but also to treat at the user end.
The conventional processes for pollution abatement are either physico-chemical or biological. The physicochemical methods aim at shifting the pollutants (land fill), concentrate the pollutant (adsorption), transfer the pollutant to another medium (air stripping) or cause secondary pollution (chemical precipitation leading to sludge). Biological techniques require narrow range of operating conditions. Electrochemistry provides technologies that have definite advantages than the above conventional methods. Electrochemical methods are versatile and offer not only clean but also cleaning technologies.
The utility of electrochemical environmental techniques are expanding with the understanding and development of electrochemical engineering that led to design and development of novel electrodes and cell structures. The invention and large scale availability of improved polymeric and perfluorinated ionomers membranes have totally changed the purification and separation processes. Electrochemical analytical and sensing techniques are playing an important role in pollution control. Water quality up-gradation by electrochemical technique presents various alternatives, such as anodic, cathodic, direct and indirect methods to treat any type of contaminants in water and waste water. These methods, at the point of entry of pollutants into the environment, help not ony to remove the contaminant but also to recover and recycle useful chemicals.
The electro-remediation of contaminated soil is, now, a proven and viable technology to prevent the pollution of water at the point of contamination itself. In this paper, the environmental applications of electrochemistry and some of the important and recent developments in the electrochemical methods of water and effluent treatment are reviewed. Electrochemical processes for decontamination of water from ions developed by CSIR-CECRI are also briefly described.