K.B. Specialty Foods has been operating for more than 40 years in Greensburg, Ind. The plant employs 270 associates and produces deli salads, cake icing and refrigerated side-dish products. It has been a zero-waste facility since 2014, and has diverted more than 90% of waste produced from going to the landfill each year.
K.B. needed to increase treatment capacity to accommodate production, but also wanted to reduce costs, mitigate odors in the community and improve the consistency of the final effluent. The company wanted to capture and utilize biogas from anaerobic digestion to help power plant operations and reduce fossil fuel consumption.
“A bed of anaerobic bacteria digests the solids, oils and soluble organics present in the plant wastewater. The main byproduct of the biochemical reactions is biogas, a gas mixture containing methane, carbon dioxide, hydrogen sulfide and trace amounts of other gases,” said Daniel Bertoldo, process engineer for ADI Systems.
The plant remains committed to reducing its impact on the environment by using natural resources responsibly. The company replaced the wastewater treatment system with an anaerobic digester featuring a dome that captures biogas from food byproducts and converts it to energy. Its first digester was installed in 2013 at the distribution center in Compton, Calif.
“The start-up of the new treatment plant had to coordinate with keeping production running and the old facility operating,” said Michael Bokelman, maintenance engineer for K.B. Specialty Foods. “The new plant had to be slowly ramped up, and there was a lot of communication and coordination required. It took everyone working together to complete this task successfully.”
K.B. needed to increase wastewater treatment plant capacity to accommodate future increases in plant production. An ADI-BVF reactor and ADI sequencing batch reactor (SBR) were installed to increase this capacity to 325,000 gal per day (gpd) and replace the previous wastewater treatment system.
“The primary goal for the upgrade project was to replace an aging, problematic treatment plant. The existing treatment plant consisting of a primary DAF and activated sludge system required near-round-the-clock operator attention, was frequently overloaded, and was a process bottleneck for K.B. Specialty Foods’ expansion plans,” Bertoldo said. “The consistent final effluent quality and biogas production rate from the new treatment plant have given K.B. Specialty Foods the confidence to completely decommission and disassemble their existing activated sludge system, remove the primary DAF from site, and renovate the building space previously used to house the DAF.”
K.B. wanted to reduce operating costs associated with chemicals, electrical and manpower. With the new system, chemicals associated with running the primary DAF clarifier were eliminated. Caustic addition had been reduced and limited to providing a small dosage of supplemental alkalinity to the ADI-BVF reactor.
Power consumption associated with the system is low, and the wastewater treatment plant is a net producer of energy. Operation of the expanded treatment plant is less operator-intensive than the previous system and does not require full-time coverage.
The anaerobic digester is the heart of the wastewater treatment plant. It eliminates the primary DAF clarifier and the foul odors associated with its operation in the Greensburg community.
“The anaerobic digester is the critical unit [in] operation in the wastewater treatment plant, as it serves as the workhorse for the overall plant,” Bertoldo said. “The anaerobic digester needs to treat the variable hydraulic and organic loads coming from the treatment plant and discharge a consistent quality effluent to the aerobic polishing system, and the simple design of the reactor makes this happen. The anaerobic digester simplifies the operation of the overall treatment plant and provides a high degree of process stability, which allows K.B. Specialty Foods to consistently meet their discharge limits and generate recoverable energy from their wastewater.”
The wood chip biofilter is used to neutralize odors from the headspaces of the influent equalization tanks. Design and operation of the biogas collection, transmission, flaring, and utilization system minimize the release of hydrogen sulfide to the atmosphere.
“The high energy value of the biogas means that the anaerobic digester creates a recoverable energy source from the plant wastewater, and K.B. Specialty Foods takes advantage of this by utilizing the biogas to create heat and power,” Bertoldo said. “The anaerobic digester removes the vast majority of the organics in the wastewater, and a consistent quality effluent from the digester is discharged to the aerobic polishing system prior to discharge to the municipal treatment plant.”
The ADI-BVF reactor removes the majority of the organic load in the wastewater, generating a consistent quality anaerobic effluent to the SBR. The operation of the SBR generates final effluent which meets the discharge limits for biochemical oxygen demand; total suspended solids; total Kjeldahl nitrogen; fats, oil and grease; and pH.
“The new treatment plant combines multiple unit operations: solids grinding and screening, wastewater equalization, anaerobic digestion, aerobic polishing, biogas scrubbing, and biogas utilization,” Bertoldo said. “Integration of all unit operations and coordination of multiple process controllers was necessary to allow the treatment plant to run smoothly. The collective efforts of K.B. Specialty Foods, ADI Systems, and multiple equipment vendors resulted in a functional treatment plant which is fully monitored from K.B.’s network.
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