Tyson Foods’ broiler processing plant in Cumming, Ga., was meeting its effluent treatment limits for its wastewater. But, Eric Maltman, wastewater treatment plant manager, and Randy Payne, complex environmental manager, found ways to reduce treatment costs while removing more nutrients from the effluent.

Wastewater treatment begins at the processing plant where the offal screens and the flow equalization basin are located. The wastewater is then pumped three quarters of a mile to the site of the wastewater facility. The treatment system consists of two DAFs, a 2.5 million gallon (mg) covered anaerobic tank, a 2.5 mg aerobic tank, oxidation ditch and the clarifier.

A few years ago, Maltman and Payne wondered if they could control the disolved oxygen level in their treatment system at some point so that they could get biological nitrification and denitrification to occur at the same time. Achieving this would reduce chemical costs and remove more nutrients.

After reviewing Cumming’s treatment system, they decided that the oxidation ditch, which had been used as a nitrification basin for 20 years, could be operated in a dissolved oxygen range that would promote both nitrification and denitrification. By doing this, the oxidation ditch could be used as an anoxic polishing reactor, since another reactor was available for nitrification.

They decided to reconfigure the wastewater system from a two-stage system into a full three-stage Bardenpho system.

Why it works

When biological nitrification and denitrification of wastewater are plotted against dissolved oxygen concentration, there is a dissolved oxygen concentration where these two processes intersect.

Within one week of the system change, effluent nitrate levels dropped from a historical range of 30 to 50 milligrams per liter to less than 10 milligrams per liter. By adding an additional carbon source, the nitrate concentration has been dropped as low as 2 milligrams per liter. No capital funding was used in this conversion, but Payne said that it would not have been possible without the Supervisory Control and Data Acquisition (SCADA) system.

The SCADA system has become one of the most important elements in the operation of the wastewater treatment system at Cumming, according to Payne. "It has revolutionized the bio-phosphorous and denitrification processes and has created a paradigm shift from a manual operations mode to a verification mode," said Payne.

Tyson’s Cumming processing plant slaughters 260,000 head of 6.0 pound broilers per day. The wastewater treatment plant has a design flow of 2 million gallons per day (mgd) but is now discharging 1.2 mgd.

Tyson Foods, Cumming, Ga., was selected by the U.S. Poultry & Egg Association as the winner of its 2008 Clean Water Award for full treatment facilities.