GNP Company raises the bar on sustainable poultry wastewater treatment

Winner of a 2013 Clean Water Award, GNP Company uses next-generation wastewater treatment technology to exceed regulatory standards and meet sustainability goals in poultry processing.

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GNP Company takes environmental sustainability seriously, and it shows at the poultry processing plant in Cold Spring, Minn., where investment in next-generation wastewater treatment technology helps it exceed regulatory requirements for effluent discharged into the Sauk River.  

GNP Company’s Cold Spring chicken processing plant is the winner of the 2013 Clean Water Award in the wastewater full-treatment category. The award is presented annually by U.S. Poultry & Egg Association.  

With the installation of a membrane bioreactor in 2011, GNP Company has been able to meet or exceed increasingly stringent nutrient limits set by the Environmental Protection Agency and the Minnesota Pollution Control Agency. The facility’s wastewater discharge is now cleaner than the regulatory requirements by orders of magnitude (see Treated water and final effluent results).

Membrane bioreactor technology

The MBR in Cold Spring has the capacity to treat 1.7 million gallons of wastewater per day. It vacuums wastewater through 0.04 micron openings in hollow membrane fibers. The automated s ystem runs 24 hours a day, seven days a week.

“The membrane bioreactor technology, which incorporates biological phosphorus and ammonia removal, better prepares the plant for current and future limits,” said Clay Watson, environmental services manager.

Wastewater treatment technology

The Cold Spring facility is a showcase of wastewater treatment technology:

 

  • The wastewater treatment facility employs membrane bioreactor technology, ultraviolet disinfecting and sand filtration.  
  • The blower system, which is the most energy efficient available, runs between 30,000 and 35,000 RPM and produces up to 2,800 cubic feet per minute.  
  • Variable frequency drives in the blower system control energy use according to the facility’s needs.  

 

Wastewater treatment by the numbers

Cold Spring is the first poultry processing plant to use MBR technology for wastewater treatment and is currently one of the largest MBR facilities in Minnesota (and in the world in terms of gallons processed per day). System volumes are as follows:  

 

  • 1.4 million gallons of wastewater are processed daily  
  • 400,000 to 500,000 gallons daily are reused in non-bird contact tasks, such as cleaning floors, screening, bird module washing, vacuum pumps, compressors and cooling towers and lawn sprinkling  
  • Water use intensity (the amount of water per pound of bird produced) at 1.61 gallons per pound decreased by 4.5 percent in 2011 from 2010.  
Water usage is based on the plant’s production of 190,000 birds per day, 6.6 gallons of water per bird, or 28.8 million gallons per month, and 8.9 million gallons per month of reconditioned water.  

 

How MBR works

The hollow membrane fibers are at the heart of the MBR system. Unlike in other filtration systems, the wastewater flows outside-in as a vacuum is pulled through 0.4 micron openings in the fibers. Pumps periodically reverse pulse to change the direction of the flow to keep the fiber media clean and free of particulates.

The Cold Spring system, which incorporates 1,012,000 fibers, has four tanks or trains, with two fiber cassettes per train, or eight cassettes total. The system can be readily expanded by installing additional cassettes.

Environmental values at GNP Company

To be sure, the EPA and Minnesota Pollution Control Agency have stringent limits on nutrients discharged into the Sauk River, but GNP Company’s investment and operational practices are driven by more than the regulations. The state-of-the-art membrane bioreactor in operation in Cold Spring, in fact, is just the most visible sign of a corporate commitment to protect the environment.

In 2010, GNP Company conducted a life cycle assessment to measure the environmental impact of its Just BARE chicken product across the value chain. The assessment showed that a significant portion of the environmental impacts fall outside the company’s direct operational control.

 

  • 35 percent of greenhouse gas emissions occur “upstream” and are related to growing corn and other feed ingredients.  
  • 37 percent come from its own operations, including the energy used in facilities and materials in packaging.  
  • 28 percent occur “downstream” and result from activities like distribution, retail, cooking and disposal.  

 

While the company’s initial focus has been on reducing environmental impacts that are within its control, there are plans to engage grain producers, growers, retailers and customer partners in creating positive change across the entire supply chain.

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