CHLORINATION AND MUSSEL CONTROL IN THE COOLING CONDUITS OF A TROPICALCOASTAL POWER-STATION

The rationale for the present study has been the continued problem of biofouling in the cooling conduits of Madras Atomic Power Station (Kal pakkam), in spire of intermittent chlorination used as a fouling contr ol measure. A diver-assisted inspection of the tunnel proved that the green mussel, Perna viridis (L.) was the major component of the foulin g community inside the cooling conduits. Maximum biomass value recorde d was 211 kg/m(2), observed inside the forebay shaft at a depth of 22. 5 m. The total biomass of fouling in the entire tunnel system was esti mated to be 578 tonnes, of which the contribution by P.viridis alone w as 411 tonnes. High-level chlorination, followed by continuous low-lev el chlorination brought large quantities of sessile biomass from the t unnel to travelling water screens (TWS). A total biomass of about 187 tonnes of fouling debris was collected from TWS during February 1988 t o January 1990. Of these, P.viridis accounted for 164 tonnes, The size -frequency distribution of P.viridis collected on the TWS clearly show ed that the appearance of young mussels (0-2 cm shell length) was corr elated with the breeding pattern of green mussels in the adjacent coas tal waters. The present study showed that intermittent chlorination is an ineffective method for mussel control in the power station cooling conduits. Continuous high-level chlorination is useful for dislodging established mussel communities from intake tunnels.