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 waterrnsupplies have been attributed to algal sources. Periphytic algal growth on the surface of drinkingrnwater conveyance structures (e.g., open channel canals) may induce seasonal T&O episodes.rnOver the past four years growth of periphytic algae on the walls of a concrete-lined canalrnconveying surface water has preceded the release of T&O compounds (MIB and Geosmin atrnrates 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 periphyticrnbiomass and preventing T&O production in the aforementioned canal. However, the use ofrnfixed-surface biocides to prevent periphytic algal growth before algae start producing T&Orncompounds may be more desirable. The main objective of this study was to determine therneffectiveness of three antifouling coatings and nine concrete mix formulations to inhibit thernperiphytic algal growth on concrete structures. The antifouling coating EP2000 was a betterrninhibitor of periphytic algae than the protective barrier coating Sun Wave. EP2000 and SunrnWave reduced periphytic algal growth by 99 % and 35 % for up to 3 months when compared torncontrol substrates. Algal growth inhibition was found to be directly proportional to the concreternsamples zinc concentration. On-going research will be focused on the performance of EP2000rnand Sun Wave for longer periods of time in two source waters. A more comprehensivernexperimental matrix involving 40 mixture designs is currently in progress.