Existing Metal Removal Technologies: Demerits

Abstract

The currently practiced technologies for removal of pollutants from industrial effluents appear to be inadequate, often creating secondary problems with metal-bearing sludge, which are extremely difficult to dispose of. The process cannot precipitate metals to low levels of solubility unless additional treatment reagents are employed, the use of which may significantly add to the volume of sludge. Most authorities consider such treatments to be best performed in specialized environments by trained personnel. Further, research findings have clearly raised strong doubts about the advisability of the use of synthetic coagulants used for metal removal. Their usage leads to several serious demerits concerned with the central nervous system of human beings. For electroplating and finishing industries, the cost involved in the treatment of effluent produced is sometimes prohibitively expensive, especially for the smaller installations, and far outweighs the advantages of recycling and regenerating materials. Present treatment strategies require costly chemical and physical operations and involve a high degree of maintenance and supervision. While wastewater treatments by ion exchange resins are both effective and convenient, they are too expensive to be used by the developing countries and their availability is limited to developed nations of the world. Government closely monitors their handling and disposal, in most instances. Processes like reverse osmosis include many of the small organic molecules that are precursors of trihalomethane generated during chlorine disinfection. The Environmental Protection Agency (EPA) strictly limits the allowable amounts of these compounds in drinking water based on the possibility that chronic exposure to them could cause cancer.