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MEASUREMENT AND CONTROL OF FOULING IN FINE PORE DIFFUSER SYSTEMS
Citation:
Barnhart, E. L. AND M. Collins. MEASUREMENT AND CONTROL OF FOULING IN FINE PORE DIFFUSER SYSTEMS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-94/102 (NTIS 94-200904), 1994.
Impact/Purpose:
Information.
Description:
The purpose of the study was two-fold: First, to define the efficiency of various methods of cleaning fine pore diffusers and, second, to develop a methodology that could be used to evaluate the efficiency of the cleaning techniques. Dirty fine pore domes from the North Texas Municipal water District were cleaned by a variety of techniques, and the improvement in oxygen transfer efficiency was measured. The domes were reinstalled in the aeration tanks and withdrawn at various time intervals thereafter. The deterioration in oxygen transfer efficiency was then noted. The cleaning techniques were repeated, and the improvement in transfer was recorded. Overall, the domes form the North Texas Plant did not show severe fouling. Low pressure hosing appeared to be as effective as any other method in cleaning the domes. The domes deteriorated promptly after they were reintroduced into the aeration tank, but the deterioration in oxygen transfer was not severe enough to impose an unacceptable aeration cost. The technique of using an off-line aeration tank for studying the cleaning techniques provided mixed results. The comparison of cleaning techniques appeared to be properly described in this small test tank, but the degree of fouling that had actually occurred in the full-scale plant appeared to be underestimated. This probably resulted from the breakdown of slimes and fouling materials during dome transportation and handling. The cost of cleaning domes by various techniques is difficult to estimate because of a variety of site specific factors. Method was developed for estimating the cost that would be encountered in a typical case. he cost for simple cleaning was found to vary from approximately $1.20 a dome for small plants to somewhat under $0.80 a dome for large plants. This report was submitted in partial fulfillment of cooperative Agreement No. CR812167 by the American Society of civil Engineers under subcontract to Hydroscience, Inc. under the partial sponsorship of the U.S. Environmental Protection Agency. The work reported herein was conducted over the period of 1985-1987. Project summary may be ordered as EPA/600/S-94/001).