Koch Foods processing plant treats wastewater with unique sequential batch reactor

When the USPOULTRY Clean Water Awards judging team reviewed the past two years of process wastewater effluent data from Koch Foods' Gadsden, Ala., facility, it was not only impressed by the treatment plant's 100 percent compliance with Alabama's direct surface water discharge permit but also how efficiently the plant was being operated by Koch's environmental staff.

Shown are the aerators in the 3.6 million gallon final effluent flow equalization basin, FEB. The effluent from this FEB travels through the ultraviolet disinfection system prior to discharge into the Coosa River. This is the location from where treated wastewater is taken for phosphorus removal in the planned dissolved air flotation, DAF.
Shown are the aerators in the 3.6 million gallon final effluent flow equalization basin, FEB. The effluent from this FEB travels through the ultraviolet disinfection system prior to discharge into the Coosa River. This is the location from where treated wastewater is taken for phosphorus removal in the planned dissolved air flotation, DAF.

When the USPOULTRY Clean Water Awards judging team reviewed the past two years of process wastewater effluent data from Koch Foods' Gadsden, Ala., facility, it was not only impressed by the treatment plant's 100 percent compliance with Alabama's direct surface water discharge permit but also how efficiently the plant was being operated by Koch's environmental staff. This can be seen in the low percent of the permit limits utilized by the facility's effluent (Table 1).  

The major improvements already completed and others planned for the future of the facility's process wastewater full treatment system played helped the judging team decide to award Koch Foods the Clean Water Award honorable mention in 2013.  

Koch Foods purchased the broiler processing plant in Gadsden from Tyson Foods in 2007. The facility processes 400,000 broilers per day, generating approximately 1 million gallons of high-strength process wastewater that must be fully treated onsite prior to direct surface water discharge into the Coosa River.

Pretreatment plant performance

Wastewater treatment plant performance is measured by the quality of the effluent discharged.   As shown in Table 1, the Gadsden plant has monthly average concentration (in milligrams per liter) permit limits for biochemical oxygen demand, BOD, at 16 mg/L, total suspended solids at 20 mg/L, oil and grease at 8 mg/L, ammonia at 4 mg/L, and total nitrogen at 103 mg/L. In addition, the plant's Alabama Department of Environmental Management permit has a monthly average loading limit in pounds per day of 231 for BOD, and 306 for phosphorus. 

Over the past two years, the Koch Foods plant utilized a maximum of 63 percent of its oil and grease concentration permit limit, while using a minimum of only 6 percent of its ammonia concentration limit. This minimal environmental impact of the Koch Foods' effluent on the Coosa River has been achieved through a series of continuous improvement projects that tell the real story behind the Gadsden plant's environmental success.

Synthetic covered anaerobic lagoon

Since the mid-1980s, the majority of wastewater treatment at the Gadsden plant was accomplished in a 10 million gallon natural grease cap covered anaerobic lagoon. "Although the lagoon worked well most of the year, the treatment efficiency dropped off during really cold weather each year," said Jeff Seymore, Koch Foods environmental manager. "The system also created some recurring odor complaints from neighbors that had moved into the area over the years."

"Then in 2004, the EPA came out with the new [effluent limitation guidelines] for poultry processing plants," added Seymore, "and it became obvious that improvements needed to be made to the treatment system."

As a result, as soon as the purchase of the Gadsden plant was complete in 2007, project work started on constructing a new synthetic cover over the anaerobic lagoon. "It was like night and day," said Michael Dean, Koch Foods wastewater operations manager. "No more drops in plant performance through the anaerobic lagoon since the temperature was maintained at a constant level year around and we haven't had an odor complaint in years."

Sequential batch reactor

Once the anaerobic lagoon synthetic cover was completed in 2008, the Koch Foods environmental staff immediately began a second project to construct a massive, three million gallon sequential batch reactor, SBR, to provide further treatment to the anaerobic lagoon effluent.   

SBRs combine the reliability of conventional activated sludge wastewater treatment technology with supervisory control and data acquisition computer systems that have the ability to gather, analyze and make system changes based on real-time data. The advantage of SBRs is that conventional activated sludge systems require multiple tanks (e.g., oxidation ditches, clarifiers), while SBRs require only a single tank. "Also the SBR can be operated to include mixing-only periods in which anoxic periods can be induced to enhance denitrification," adds Dean. 

"Our SBR completes four cycles per day," said Dean. "The tank fills, aerates, goes through two anoxic periods, settles, we decant the effluent water and waste the required sludge over a six-hour period. The [supervisory control and data acquisition] system controls the operation and the wastewater operators do periodic checks. It has worked really well."

"It's a very unique system," said Charles Horn, retired Alabama wastewater permitting official and Clean Water Award judging team member. "I don't know of another one in the state."

Phosphorus removal system

In recent years, continued environmental pressure on the upper segment of the Coosa River in Gadsden led to the segment being declared impaired by regulatory officials for excessive nutrient loading from all sources into the river. As a result, a total maximum daily load was developed for the upper Coosa River segment that establishes the maximum amount of Phosphorus that can be discharged into the Coosa on a daily basis.

"We submitted a new [Alabama Department of Environmental Management] Wastewater Discharge Permit application back in December 2012," said Seymore. "We haven't received our new permit yet, but we already have been told by ADEM that we will be facing a seasonal summer phosphorus permit limit of 1 mg/L from March through October each year. Currently our loading (pound per day) limit equates to a limit of 35 mg/L. Now, for six months out of the year, we will have to meet a 1 mg/L effluent [Phosphorus] limit. It's going to be a challenge."

However, it is a challenge that Koch Foods plans to meet. A new phosphorus removal project has already started at the Gadsden plant utilizing a unique application of conventional DAF, dissolved air flotation, technology as a novel tertiary treatment process.

"We're going to take the SBR effluent out of our current 3.6 million gallon flow equalization basin that currently discharges to our UV disinfection system," said Dean, "and bypass that first to a DAF systems that utilizes Alum. We have done extensive jar testing and the results on the small scale look very good. We can meet the [Phosphorus] limit."

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