Coatings and Cement-based Biocides to Control Algae Growth and Taste Odor Release in Water Distribution Canals

摘要

Characteristic earthy, musty, moldy, and fishy taste and odors (T&O) in drinking water supplies have been attributed to algal sources. Periphytic algal growth on the surface of drinking water conveyance structures (e.g., open channel canals) may induce seasonal T&O episodes. Over the past four years growth of periphytic algae on the walls of a concrete-lined canal conveying surface water has preceded the release of T&O compounds (MIB and Geosmin at rates of 2 to 15 ng/L/mile) into the flowing water during the summer months. Copper applications and/or mechanical brushing techniques have been successful in reducing periphytic biomass and preventing T&O production in the aforementioned canal. However, the use of fixed-surface biocides to prevent periphytic algal growth before algae start producing T&O compounds may be more desirable. The main objective of this study was to determine the effectiveness of three antifouling coatings and nine concrete mix formulations to inhibit the periphytic algal growth on concrete structures. The antifouling coating EP2000 was a better inhibitor of periphytic algae than the protective barrier coating Sun Wave. EP2000 and Sun Wave reduced periphytic algal growth by 99 % and 35 % for up to 3 months when compared to control substrates. Algal growth inhibition was found to be directly proportional to the concrete samples zinc concentration. On-going research will be focused on the performance of EP2000 and Sun Wave for longer periods of time in two source waters. A more comprehensive experimental matrix involving 40 mixture designs is currently in progress.