Discharging treated poultry processing wastewater directly into the surface waters of the United States requires a National Pollutant Discharge Elimination System (NPDES) permit. With the continued environmental concerns about the health of rivers and streams, obtaining an NPDES permit is a major accomplishment. Renewing a permit is often even more difficult, requiring months of effort and many community meetings with concerned citizens.
Consequently, maintaining an NPDES permit into a watershed where multiple states and Environmental Protection Agency (EPA) regions are discussing the water quality standards is an extraordinary challenge. Yet, for Simmons Foods, this is another opportunity to show what clean water looks like. And that is just what the facility wastewater team in Southwest City, Missouri, does not only for their regulators but also for everyone else interested.
Committed to clean water at Simmons Foods: Andy Brashear, environmental manager; Mark Simmons, chairman of the board; Seth Walters, director of environmental quality; Mike Davis, director of engineering and wastewater operations
The Simmons Foods Southwest City Complex treats an average daily flow of 2.28 million gallons (MGD) used to process 450,000 birds and 2,000 metric tons of protein by-products as well as manufacture a dairy feed ingredient called Pro-CAL. The treated wastewater must meet levels comparable to, if not stricter than, publicly owned water reclamation facilities discharging to surface waters.
Andy Brashear, environmental manager, said, “The complex achieves its NPDES permit limitations and has done so without a notice of permit violation in 14 years. We have also passed over 34 consecutive tests for toxicity [acute and chronic whole effluent toxicity tests].”
Southwest City wastewater team: Front row (left to right) Seth Walters, director of environmental quality; Jose Rodriguez, operator; Cassie Carpenter, operator; Kim Gould, operator; Wendy Flaming, senior laboratory technician; Mike Davis, director of engineering and wastewater operations; Back Row (left to right): John Graham, operator; Larry Smith, operator; Mike Woods, operator; Andy Brashear, environmental manager; Jose Gonzalez, operator
Investment in poultry wastewater treatment
This outstanding performance has helped make Simmons the 2015 U.S. Poultry & Association Clean Water Award winner for outstanding performance in the direct discharge category, an honor it previously received in 2007. At that time, Chairman Mark Simmons said, “This is not the end of our work, however. We will continue to be environmentally responsible going forward.”
True to his words, Simmons Foods has continued to invest in a commitment to excellence in water treatment and conservation.
In 2009, Simmons Foods completed three new lagoons designed to provide more than 30 days of emergency storage, as well as providing stormwater collections and contact cooling water recirculation for the protein by-products plant. The lagoons are designed to current standards including a minimum of six inches of clay covered by a heavy-duty plastic liner. Overland flow with berms and vegetation provide additional filtration of stormwater leaving the complex, although the initial 30 minutes of stormwater runoff is diverted to the lagoons and then full treatment. This improvement, along with the purchase of adjacent lands leading to the treated water discharge location, has helped reduce the annual average fecal coliform bacteria measurements to 30 CFU/100mL as compared to the Missouri water quality standard of 200 CFU/100mL. Other related improvements include the development of a riparian buffer zone with 3,500 trees planted along the banks of the stream carrying treated water.
Wastewater reclamation uses screening
The treated water results from a unique, contemporary water reclamation process manned 24 hours per day. Treatment is comprised of primary and secondary screening to remove coarse solids, followed by an equalization basin operated to balance the extremes of the wastewater flow and concentration.
About one-half of the flow is sent to a chemically enhanced dissolved air flotation (DAF) system that removes a majority of constituents [approximately 95 percent solids, 75 percent biochemical oxygen demand (BOD5), 20 percent TKN (total kjeldahl nitrogen) and 45 percent phosphorus].
The DAF is operated to yield skimmings or a float with 25 percent to 30 percent solids, based on a requirement of at least 20 percent solids for the dairy ingredient process that uses this material as a raw input.
An anaerobic lagoon receives the remaining equalization basin flow in addition to discharges from the dairy ingredient process, water from dewatering solids wasted from the biological basins, condensate from the protein plant, facility domestic wastewater and DAF effluents diverted during sanitation.
Sequencing batch reactor
The treated water leaving the DAF and the anaerobic lagoon feed two activated sludge treatment systems in series.
The first is a sequencing batch reactor that receives approximately 1,300 GPM, of which 35 percent is from the anaerobic lagoon. Blending the remaining 250 GPM from the DAF with the flow from the sequencing batch reactor yields a wastewater comparable to domestic wastewater in terms of organic and nutrient loadings.
The second biological basin in the series is designed to remove those remaining organics and nutrients. Once the organics have been converted into biological cells, these solids are settled in a clarifier.
Additional chemical DAF improves process
In 2013, a second chemical DAF was installed between the sequencing batch reactor and second biological basin to improve settling of the sequencing batch reactor biological solids. Brashear said, “That big [sequencing batch reactor] is really good at removing nitrogen and organics, but not so good at consistently settling solids. If we sent the slow settling solids to the second basin, we carried the problem over requiring us to slow the flow or add another polymer in the clarifier.”
Since the time of the installation of a second DAF, neither polymers nor coagulants have been added to the clarifier. Additionally, the average total phosphorus discharge is 65 percent lower at 0.088 mg/L. Disk filters are used to remove any remaining solids. The effluent is re-aerated and then flowed through an ultraviolet light channel before discharge to the tributary branch.
Waste heat evaporator concentrates solids
A significant, beneficial process innovation outside of the wastewater system has been a waste heat evaporator installed to concentrate the dairy ingredient process discharge. That material, about 70,000 GPD, yielded permitted constituent concentrations well over 99.9 percent to 99.99 percent higher than the allowable discharge levels. Even with dilution into the overall wastewater flow, the loadings greatly exceeded treatment capabilities, in essence doubling the concentrations to be treated. The waste heat evaporator concentrates the solids previously disposed of off-site such that the process water sent to wastewater is now easily incorporated.
Waste heat evaporator concentrates the DAF discharge to produce a dairy feed ingredient.
The waste heat evaporator is also part of the water conservation and reuse initiatives underway. Between 300,000 and 500,000 GPD of treated effluent are recycled, representing about 18 percent of the total flow. The outcome is 4.4 gallons of water per bird (GPB) daily average for the entire complex and 4.0 GPB for the processing plant alone -- an important parameter for a complex that uses only well water. The water usage compares with the poultry industry average of 6.61 GPB.
Poultry wastewater process control worksheet
Both sensors and know-how keep the overall wastewater system in check. The sensors are typical for poultry processing wastewater, but the know-how is shared daily throughout the complex in the form of a process control worksheet. Recipients include all critical personnel operating or managing wastewater sources as well as the chairman of the company’s board of directors. The data provided by the wastewater facility’s lab technician includes the various daily parameters monitored describing wastewater system “vitals” at almost any point in the treatment process, day after day. The transparency enables all layers of management and direct reports to diagnosis potential problems based on any unusual observations.
Transparency in environmental programs
Transparency is displayed daily in the treated effluent, and it is also observed as Simmons Foods hosts about five environmental tours per year for a total of about 75 tours since 2000. All NPDES parameters are provided as well as a wastewater treatment system tour from start to finish. About 600 prominent local community leaders and citizens have visited and viewed the final effluent discharge towards the Cave Springs Branch tributary.
Seth Walters, director of environmental quality, summed up the Simmons Foods attitude towards transparency and environmental stewardship noting, “From the top down our corporate viewpoint is, friend or not friend, we want you to see what we are doing and how good we are.”