PHOENIX, Jan. 30, 2006 -- For years the city of Lemoore, CA's wastewater lagoon system has been receiving about 2.7 million gallons of domestic and industrial wastewater each day. The wastewater is composed of whey, disinfectants, cleaners, and other difficult to digest cheese manufacturing waste.
Over a period of years, the sludge blanket reached the surface of the pond creating floating islands of sludge and creating the potential for odors and elevated suspended solids and BODs that might cause a permit violation. Concerned about the loss of capacity and the potential of violating their permit, the City of Lemoore began looking for ways to remove sludge from Pond # 2.
Dredging, drying, and removal cost were estimated at about $341 per dry ton. Pond # 2 contained about 3,502 dry tons of sludge which brought total estimated sludge removal costs to about $1,194,000.
To keep the lagoon on line, and to save money, officials with the city decided to use a chemical product called Bio Energizer, from Probiotic Solutions, of Chandler, AZ, a unit of BioHumaNetics, to oxidize (or "wet burn") the sludge in place. It's a formulation of organic acids, buffers, natural biological systems, nutrients and energy systems which balance the natural microbial ecosystem to increase bio-oxidation of wastewater solids and grease which reduces odors.
After two years of using the formulation an average of two feet of sludge was removed (five feet in some places) totaling about 1,268 dry tons of domestic and cheese waste sludge. So far oxidizing the sludge in place using this method saved the city of Lemoore $321,388.
It's impressive to note that this sludge was burned up while Pond # 2 was kept on line and continued to receive its normal daily load. The formulation not only removed 1,268 tons of existing sludge but for two years also destroyed all the new sludge Pond # 2 would normally have received.
"Bio Energizer saves money, and saves time! This product really works," said Bill Keeney, wastewater superintendent for the city of Lemoore.
The organic matter in lagoon sludge is composed of dead algae bodies, bacteria, and inorganic matter like sand, grit, gravel, and clay. When more sludge is deposited than a lagoon can burn (oxidize), sludge accumulates. This natural "wet burn" process is known as bio-oxidation and is the conversion of sludge by bacteria into gasses and non gasses like; methane CH4, carbon dioxide CO2, nitrogen gas N2, hydrogen sulfide H2S, and water H2O.
The Probiotic formulation, manufactured by BioHumaNetics, accelerates the conversion of sludge to gas, ash, and water while the lagoons remain on-line. There's no draining, drying, excavating, or down time.
Oxidizing sludge in place with it isn't a quick fix nor does it reduce inorganic materials like sand, grit, gravel, or clay. Operators can expect to see an average of two inches of sludge reduction per month. This reduction includes the oxidation of existing sludge and oxidation of the new load entering the lagoon daily.
It's safe, easy to apply, non-toxic and poses no danger to operations personnel.
This article was written by Steve Harris, director of wastewater operations at BioHumanetics' Probiotic Solutions, of Chandler, AZ. Harris received his bachelor's degree from Arizona State University and has been working with lagoon operators for 14 years. Contact: 800-961-1220 or [email protected].
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