Chlorination and mussel control in the cooling conduits of a tropical coastal power station

Abstract

The rationale for the present study has been the continued problem of biofouling in the cooling conduits of Madras Atomic Power Station (Kalpakkam), in spite of intermittent chlorination used as a fouling control measure. A diver-assisted inspection of the tunnel proved that the green mussel, Perna viridis (L.) was the major component of the fouling community inside the cooling conduits. Maximum biomass value recorded was 211 kg/m2, observed inside the forebay shaft at a depth of 22.5 m. The total biomass of fouling in the entire tunnel system was estimated to be 578 tonnes, of which the contribution by P.viridis alone was 411 tonnes. High-level chlorination, followed by continuous low-level chlorination brought large quantities of sessile biomass from the tunnel to travelling water screens (TWS). A total biomass of about 187 tonnes offouling debris was collectedfrom TWS during February 1988 to January 1990. Of these, P.viridis accounted for 164 tonnes. The sizefrequency distribution of P.viridis collected on the TWS clearly showed that the appearance of young mussels (O-2 cm shell length) was correlated with the breeding pattern of green mussels in the adjacent coastal waters. The present study showed that intermittent chlorination is an ineflective method for mussel control in the power station cooling conduits. Continuous high-level chlorination is useful for dislodging established mussel communities from intake tunnels.

Greening of the coasts: a review of the Perna viridis success story

“…Both species are dominant in many rocky littoral and shallow sublittoral ecosystems and often contribute significantly to the productivity of coastal benthos (Vakily 1989;Hickman 1992). The green mussel has been attracting lot of attention not only as a potential organism for commercial cultivation (Parulekar et al 1982;Hickman 1992;Rajagopal et al 1998a), but also as a serious pest organism in cooling water conduits of marine industries (Rajagopal et al 1991a(Rajagopal et al , 1996a(Rajagopal et al , 2003a. The green mussel is characterised by fast growth and relatively high tolerance to many environmental variables, making this species relatively difficult to control using common antifouling techniques (Rajagopal 1997;Rajagopal et al 2003a).…”

Biofouling in Cooling Water Intake Systems: Ecological Aspects

“…Several incidents of plant shutdown due to fouling have been reported from various parts of the world (Imbro and Gianelli 1982 ;Rains et al 1984 ;Neitzel et al 1986 ;Rajagopal 1991Rajagopal , 2010Sasikumar 1991 ;Claudi and Mackie 1994 ) . The number of studies on biofouling of coastal electrical power plants is few (Hoshiai 1964 ;Collins 1968 ;Board and Holmes 1972 ;Relini et al 1980 ;Brankevich et al 1988 ;Rajagopal et al 1991aRajagopal et al , 1991bRajagopal et al , 1996Rajagopal et al , 2006a and most of these studies relate to problems encountered in temperate waters. Moreover, detailed studies on the community structure of biofouling assemblages and other ecological parameters such as growth rate and settlement are lacking (Rajagopal et al 2006b ) .…”

“…For example, biocide dosing strategy can be devised based on the reproductive ecology of the local species. Once the mussel settlement season is known, it is possible to use low-dose continuous chlorination (also know as exomotive chlorination) to prevent the attachment of juvenile mussels inside the CWS (Rajagopal et al 1991a(Rajagopal et al , 1996(Rajagopal et al , 2006b ) . Moreover, one can also supplement the test panel data with real-time data obtained through the use of fouling monitors (Claudi et al 2012 ) .…”

“…The green mussel Perna viridis is a major pest in CWS of Indian power plants (Rajagopal et al 1996 ) . Other mussel species such as Perna indica and Brachidontes spp.…”

“…Temporal changes in biofouling development can be conveniently studied using test panels (WHOI 1952 ;Costlow and Tipper 1984 ;Rajagopal et al 1996Rajagopal et al , 2006a . With this method, it is possible to study the seasonal variations and ecological succession in sessile benthic communities and the major factors infl uencing such changes (Dayton 1971 ;Connell and Slatyer 1977 ;Smedes 1984 ) .…”