Pesticides:

Pesticides cover a wide range of compounds. They include inorganic compounds such as copper sulphate, chlorinated hydrocarbons such as DDT and Aldrin, etc. Pesticides come into natural water from direct application for aquatic plants, insect control and percolation, run-off from agricultural fields and discharges from industries. The organic compounds especially chlorinated hydrocarbons are toxic even when present in traces and make the chemical and bio-chemical degradation reduced. Discharge of pesticides in the water course has to be controlled because accidental discharge of pesticides in bulk becomes more serious causing death of fish and other aquamarine life, which may necessitate the water intakes to be temporarily shut down. Removal of pesticides is done by oxidative treatment using ozone, chlorine dioxide or potassium permanganate. Absorption by activated carbon is most effective.