Midwestern Dairy: A Study in Plant Efficiency

The country’s leading producer of Swiss cheese produces over 200,000 lbs of cheese daily. In addition, the company supplies whey products, dairy proteins, and powders to food manufacturers. These resulting waste streams are sent to the facility’s wastewater treatment plant (WWTP), which is an aerobic treatment system utilizing the activated sludge process. Components of this system include the following:

• Equalization basin – A capacity of approximately 350,000 gallons
• Selector tank – A portion of the return activated sludge from the clarifiers is discharged into the selector tank
• Three lagoons – Each “clean” lagoon has a capacity of approximately 2.4 million gallons. Part of the return activated sludge from the clarifiers is discharged into the fully aerated (primary) lagoon.
• Two rectangular clarifiers
• Partially aerated secondary lagoon
• Settling tertiary lagoon

In an effort to improve the performance and treatment capacity of this plant, the cheese processor hired ATI in early 2007 to perform an evaluation, which suggested the following upgrades:

• Modifications to the equalization tank to improve wastewater equalization and reduce the hydraulic retention time of the wastewater.
  

  New aerated pond

• Removal of the current mechanical aerators and installation of a new floating-lateral diffused aeration system for the primary lagoon. This will allow more efficient transfer of oxygen to the microscopic organisms, increasing BOD and TKN removal.
• Installation of a new secondary clarifier to increase the solids loading capacity and allow for better solids capture.
• Installation of a new tertiary filter system to polish wastewater to required phosphorus permit limits before discharge.

ATI completed the drawings in March 2008, and construction was completed in July 2008. In today’s harsh economy, the pressure to cut costs and increase efficiency is greater than ever before. With a sharply tuned wastewater treatment system in place, this cheese processor can rest assured that it is cost-effectively meeting its discharge requirements.