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CYANOBACTERIA PASSAGE DURING FILTER PERTURBATION EPISODES
Citation:
Dugan*, N AND D J. Williams*. CYANOBACTERIA PASSAGE DURING FILTER PERTURBATION EPISODES. Presented at WSWRD Peer Review, Cincinnati, OH, September 27 - 29, 2004.
Impact/Purpose:
To inform the public.
Description:
Eight pilot-scale in-line filtration trials were performed to evaluate the passage of cyanobacterial cells through drinking water filters after sudden increases in hydraulic loading rates. Trials were performed at 30 C using two coagulant combinations (aluminum sulfate and cationic polymer or ferric chloride and cationic polymer), two initial filter loading rates (7 or 10 m/hr) and two species of morphologically different cyanobacteria (Microcystis aeruginosa or Anabaena flos aquae). Cyanobacterial suspensions were seeded into the filter influent for 2.3 to 3.4 hours prior to perturbation. The filter was perturbed by instantaneously increasing the hydraulic loading rate by 50 percent. Filter influent and effluent water qualities were characterized by measuring turbidity, particles, chlorophyll a and cyanobacterial biovolume. The observed post-perturbation filter effluent chlorophyll a peaks were 1.6 to 48 times greater than the pre-perturbation averages. The post-perturbation effluent turbidity peaks were 1.4 to 7.2 times greater than the pre-perturbation averages. The post-perturbation effluent particle peaks were 6.5 to 25 times greater than the pre-perturbation averages.