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This study addresses the colonization of a submerged hollow fiber membrane-based watertreatment plant by a population of pulmonate snails. Physical shearing of the fibermembranes caused by embedded calcareous shell structures, has created a challenge inmeeting membrane integrity testing. Chlorinedioxide (ClOsub2/sub) has been successfully used in treating and preventing the proliferation ofboth bivalve and gastropod mollusks. The biocidal effectiveness of ClOsub2/sub is consideredsuperior to that of chlorine and hypochlorite in penetrating cell wall structure, acting onthe colloidal nature of protoplasm, and suspending cellular enzymatic activity.Additionally, ClOsub2/sub has been shown to have added advantages over chlorination byimproving the removal of organic carbons and minimizing disinfection byproduct.A definitive bioassay was developed to establish the ClOsub2/sub dose concentration andexposure that would effectively inactivate the life cycle of the resident snail. Resultsderived from initial bench scale dosing experiments performed on a laboratorypropagated snail culture, suggest that continuous dosing at lower concentrations may bemost effective by inducing a perpetual moribund state. In contrast, it was found thatintermittent dosing at levels tenable for drinking water application, were ineffective atinactivating all of the life stages tested. Microscopic observations of the blastula andembryo stages made it possible to identify the egg bound vitellus content as a majorprotective barrier against oxidation. Additional chemical dosing trials are scheduled tobe conducted in a custom built monitoring chamber stationed at the affected watertreatment plant. Concurrent studies will be performed aimed at evaluating theeffectiveness of ClOsub2/sub as a pretreatment option to mitigate downstream Total Trihalomethane (TTHM) formation. Includes abstract only.

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Edition: Vol. - No. Published: 11/01/2009 Number of Pages: 1File Size: 1 file , 720 KB