Special activated sludge system works well as small town`s first WWTP

- By:

Courtesy of Fluidyne Corporation

The public works superintendent and his consulting engineer here report successful operation of a special activated sludge wastewater treatment plant (WWTP) for St. Philip’s since the end of 2003, with a similar and larger plant scheduled to start up for Portugal Cove later this year.

The currently operating plant, with design average flow of 7.7 liters/sec. and peak flow of 28.5 liters/sec., has consistently met effluent standards for biochemical oxygen demand (BOD), total suspended solids (TSS), total nitrogen (TKN), phosphorus (P), and fats/oils/grease (FOG). It has required only minimal, routine, maintenance-class operator attention, and has converted 99.999% of influent solids to landfill-disposable sludge. The larger plant is to handle design average flow of 15.2 liters/sec. and peak of 34.2 liters/sec.

The ISAM™ Integrated Surge Anoxic Mix System, manufactured by Fluidyne Corp. of Cedar Falls, Iowa, is specially designed to provide for lower amounts of sludge production compared to other activated sludge processes. Here, the system has processed over 129,000,000 US gal. of raw sewage since startup, and to date only about 15,000 US gal. of sludge has been removed. Fluidyne indicates similar results have been realized at numerous installations in the U.S. and Canada. The company’s local rep firm, ENG Environmental Technologies Inc. of Halifax, NS and St. John’s, NL, participated in system design, was on-site throughout installation, and remains committed to ongoing service as needed.

The St. Philip’s WWTP was the first treatment system for the town. The second system, presently under construction on the Portugal Cove side of town, is a direct result of the success of the first installation. The projects represent fulfillment of the joint local government’s 2002 commitment to proactive environmental protection for their pristine harbor, on behalf of both local residents and a growing tourism industry. The commitment not only includes exceeding all present guidelines, but also more stringent guidelines that are pending---without the use of chemical additions.

At St. Philip’s, where sewage for the 300 residences(850 PE) and a few commercial operations was previously handled via septic tanks, WWTP influent levels are BOD, 200 mg/l; TSS, 250 mg/l; TKN, 50 mg/l, , and FOG, 50 mg/l. The Provincial Dept. of Environmental and Conservation for Newfoundland/Labrador presently requires effluent treatment levels for BOD of 20 mg/l and TSS of 30 mg/l, with reduction to 10 mg/l for both parameters by both provincial and federal regulators considered possible within a few years. The new plant has consistently met the 10 mg/l level, with less than 5 mg/l measured more than 90% of the time.

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