Tyson Foods, Wilkesboro, N.C., is close to the community in more ways than one. Not only is the company Wilkes County’s largest employer and a vital part of the local economy, the processing facility is shoehorned into the city of Wilkesboro with residences and businesses located in close proximity on all sides. Any environmental miscues would be up close and personal for the surrounding community, and, for Tyson, this means good wastewater treatment makes good neighbors.
Good thing that producing clean wastewater efficiently is something at which Tyson Wilkesboro excels. In fact, it gained honorable mention in U.S. Poultry & Egg Association’s 2010 Clean Water Awards in the pretreatment category.
3.5 million gallons a day
Tyson Wilkesboro is one of the nation’s largest poultry processing and further-processing facilities. In the process of slaughtering and processing 330,000 chickens and producing 252,000 pounds of further-processed poultry meat a day, the Wilkesboro facilities generate a wastewater flow of about 3.5 million gallons each day.
Wastewater from two fresh plants and a foodservice further processing facility is pretreated before being released to Wilkesboro’s publicly owned treatment works (POTW).
Relationship with the city
Managers at Tyson Wilkesboro work hard at maintaining a good relationship with the city of Wilkesboro. Processing plant manager Bob Johnson explained, “Tyson has a very good relationship with the city of Wilkesboro, and from the day this plant was built that has been the case. It has always been a partnership when it comes to wastewater and any other issues that might arise. When you are sitting on Main Street, as we are, there is always a sense of ownership involved.”
And when Bob Johnson says Tyson Wilkesboro is involved in the community, he really means it – including the wastewater treatment facilities. An extraordinary demonstration of this involves MerleFest, a bluegrass music festival held annually, which attracts thousands to Wilkesboro – including campgrounds surrounding the Tyson Wilkesboro wastewater aeration lagoons.
Wastewater treatment manager Jim Brown makes a practice of visiting with campers on sites surrounding the facility every year. “I always ask the campers how things are going and about their camping conditions. I seldom receive complaints about odor or anything else,” Brown said.
Tyson also adopted for cleanup a mile of stream into which Tyson Wilkeboro’s stormwater flows. Downstream, part of this unnamed tributary to Cub Creek was stocked with trout by the City of Wilkesboro.
Stormwater BMP and SPCC
Spill prevention, control and countermeasures (SPCC) are maintained, along with a state-mandated stormwater best management practices (BMP) plan, which includes capturing stormwater in seven outfalls and conducting sampling at two points. A system of raised drains and ditches capture the first flush of stormwater, which goes into the wastewater pretreatment system.
A critical component of the waste stream originates in the offal room, and when offered the responsibility for overseeing offal operations several years ago, wastewater treatment manager Jim Brown saw it as an opportunity to gain better control over what goes into the wastewater treatment system.
Baleen screening is used with primary screening in the offal operation and secondary screening in wastewater pretreatment.
From the offal department, wastewater flows into a 60,000-gallon wet well before being pumped into an 80,000-gallon acidulation tank where wastewater pH is reduced to between 4.0 and 4.5.
DAF operation: Experience required
After acidulation, wastewater flows into the dissolved air flotation (DAF) system. DAF is a hands-on process at Wilkesboro, where experienced wastewater treatment operators maintain manual control of the process.
The system includes four older Nijhuis DAF units with no flocculation tubes and no automatic controls on the valves. The valves are adjusted manually to achieve even cross flow.
“Visitors to our facility who have newer, more automated DAF systems sometimes wonder how we manage the system without the automation,” said Brown.
Approximately 1 million gallons of DAF effluent is recycled for processes such as feather washdown and operation of vacuum pumps.
Seven-day equalized flow
After DAF treatment, wastewater flows to a pumping station that lifts the effluent to two aerated lagoons which help achieve a seven-day equalized flow to the POTW.
The Wilkesboro POTW provides final treatment before the effluent is discharged into the Yadkin River.