PRETREATMENT OF A FOOD PROCESSING WASTEWATER CONTAINING EXTREME LEVELS OF BOD, FOG AND TSS USING A HIGH RATE ANAEROBIC PROCESS
Abstract:Litehouse Foods, Inc. produces salad dressings at facilities located in Lowell, MI and Sandpoint, ID. The company was processing wastewater by isolating and hauling small quantities of very high strength wastewater generated during the primary clean-up process at the plants and discharging subsequent rinse waters directly to the local POTW.
In an effort to develop a sound long-term wastewater pretreatment approach, Litehouse evaluated several alternatives for biological treatment. Specifically, Litehouse needed a technology capable of handling very high concentrations of BOD, TSS and FOG in a cost effective way. Samples of the wastewater from both Litehouse locations indicated ranges from 50,000 to 150,000mg/L for BOD, TSS, and FOG.
Upon completion of a technology review, Litehouse decided to conduct a pilot study using a novel high rate anaerobic process manufactured by NewBio, Inc.
The pilot plant consisted of a 2,000 gallon equalization tank, an 8,000 gallon anaerobic digester with 6,000 gallons of hydraulic capacity, and the related operating and control equipment. Batches of wastewater were screened through a 1/8” screen before entering the equalization tank. Each batch was sampled and treated in the digester. Reactor loading rate were held to 150 gallons per day at start-up and increased to 500 gallons per day by the end of the pilot. The pilot data indicates that concentrations of BOD, TSS and FOG were reduced >99%, >98%, and >99% respectively at a peak loading rate of 17 kg BOD/m3 of reactor volume.
Based on the success of the pilot, Litehouse proceeded with the design and installation of pretreatment plants using the anaerobic technology at both locations. Applied Technology, Inc. was retained to complete the pretreatment process design for both locations. The plants consist of flow equalization, two NewBio anaerobic digesters, and sulfur removal. The first plant was constructed in Lowell, MI, beginning in September 2000. The digesters were started-up in December 2000. The second plant is scheduled for installation in Sandpoint in the fall of 2001.
This paper will discuss the pilot study, including operational issues and test results, the technology and provide start-up and operational data from the full-scale systems.
Document Type: Research Article
Publication date: January 1, 2001
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