Performance of polymeric membrane systems in the treatment of poultry processing plant waste effluent
Nelson, Heather M.
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Water use is a chronic problem for poultry processors because of costs and the disposal of liquid waste which often has high levels of BOD and turbidity. One of the most water intensive steps in the primary poultry slaughter operation is the immersion chilling step which requires the use of 1.7 liters/bird. In the primary and secondary processing levels of conversion of live birds to meat, processors use fresh water at an average of 26.5 liters/bird. This research study tested the performance of a submerged ultrafiltration system membrane module to treat the immersion chiller water in order to meet requirements for reducing fresh water use in this processing step. The second part of this study tested the effectiveness of a membrane bioreactor to treat the wastewater for disposal or reuse. Both systems use polymeric PAN membranes with 0.05 micron pore size. The first study with the immersion chiller water showed that regulations for water quality can be met with the membrane treatment. Results suggest that the ultrafiltration 2system can be operated continuously for 4-hours at an average rate of 16.0 L/h·m by slightly pressurizing the permeate side of the membrane to backflush foulants deposited on the feed side without having to remove the membrane module off-line for cleaning. Collaborators working on the economics of the process believe that a significant cost (water overflow and refrigeration cost) savings of about $80,000/yr can be obtained on this operation by recycling chiller water. The second study used a membrane bioreactor (MBR) which consisted of three tanks, an aerobic bioreactor tank, anoxic settling tank, and a third tank which houses the membranes. The most effective ultrafiltration cycles, which maximized permeate flux, minimized variation in retention times, and produced a steady state concentration of biodegradable material in the effluent were ultrafiltration for 1 hour followed by 120 sec backflush and ultrafiltration for 20 min followed by 20 sec backflush. Quality of water leaving the MBR system through the ultrafiltration module met requirements for discharge into the municipal sewer without surcharges and also met requirements for reuse in processing on raw product.