Case Study: Poultry Processing Wastewater Treatment System Improvement
Petrox DN® bioaugmentation was implemented at a poultry processing plant to deal with a recurring problem of excessive ammonia levels in wastewater discharge. Petrox ND® bioaugmentation reduced the organic carbon load in the wastewater and converted the ammonia to nitrogen gas. Within 48 hours of treatment the ammonia levels in the wastewater were reduced to acceptable levels and discharge limits were maintained.
Nature of the Problem
Wastewater treatment requires the treatment of a variable waste stream with limited control over the volume and concentration of the raw material and only moderate control over the operating conditions. The goals for organic wastes include the removal of organic pollutants, reducing the total organic load, reducing nutrient concentrations including nitrogen, and odor control. Removal of ammonia and nitrogen compounds are typically achieved by a two- step process of nitrification of the ammonia and denitrification of the nitrate. The autotrophs Nitrosomas sp. and Nitrobacter sp. are typically involved in these steps. As autotrophs these microbes use carbon dioxide instead of organic carbon to build cells, organic wastes are not treated by this process.
The Pseudomonas sp. in Petrox DN® oxidize the organic carbon wastes converting it to cell mass, carbon dioxide and water and generating stored cellular energy. Simultaneously, the Pseudomonas sp. in Petrox DN® remove ammonia and nitrogen by utilizing these compounds as a nitrogen source for cell growth and electron acceptors during the consumption of the organic wastes. The benefit of Petrox DN® bioaugmentation is the removal of both the organic waste, nutrients and elimination of ammonia odors.
Pseudomonas sp. are also cold water tolerant, so Petrox DN® can be used year round under most under natural conditions.
The plant generates 0.85 million gallons of wastewater per day with ammonia levels of 80 to 120 ppm. The wastewater after primary treatment and equalization flows into a 7.5 million gallon anaerobic lagoon and subsequently four sequencing batch reactors (SBRs). At the end of the settling cycle, the supernate discharges to a receiving stream.
Bench-scale laboratory studies showed that nitrate could be removed at a rate of 17 mg/L/hr under aerobic conditions and at a rate of 12 mg/L under anaerobic conditions. TOC could be removed at a rate of 45 mg/L/hr. Petrox DN® bioaugmentation was initiated in the aeration basin and the SBRs.
After less than 48 hours the wastewater met and maintained the wastewater discharge limits.