Impact of thermal discharge on marine environment - an overview

Thermal pollution has been used to indicate the detrimental effects of heated effluents discharged by power plants and other industries. It denotes the impairment of quality and deterioration of aquatic and terrestrial environment through heated effluent and fly ash. Various industrial plants like thermal, atomic, nuclear, coal fired plants, oil field generators, factories and mills utilize water for cooling purposes. In India, there are about 60 thermal power plants, which produce 30 million tonnes of fly ash every year. The heated effluents from power plants is discharged at a temperature, which is 8-10 degC higher than that of intake marine water. The adverse effect of thermal discharge are visible in microorganism, fish, biotic life and the over all ecosystems. The discharge of heated effluents actually affects the fish respiration, metabolism and other physiological activities of marine organisms, which ultimately leads to death. This could be due to synergism because of toxic chemical such as copper, nickel, chromium and chlorine, which are used to remove slimes in the pipelines. The major waste material from thermal power station is the fly ash that creates enormous pollution problem to air, water and soil environment. Fly ash possess large amounts of lead, cobalt, chromium, cadmium etc. When this fly ash is released out through water carriage system it leads to turbidity, over deposition and flood also. Tuticorin Thermal Power Station (TTPS) has installed five power generation units each of 250 MW capacities. About 1.35 lakhs m3/hr water is drawn from the sea, utilized for cooling and then the heated effluent is discharged into the same environment. Therefore, this paper deals with various impacts associated with thermal discharge on marine environment. (author)