Located in St. Cloud, WI, Baker Cheese has been producing cheese since 1916. In the 1950’s, the decision was made to only produce mozzarella cheese and, through the recognition of consumer demand, Baker created the Original Baker String Cheese. Today, the fourth generation of Baker’s are still leading the way in string cheese, currently using about 2M lb/milk per day to make only string cheese. As the desire to increase production and add on-site whey processing had become a reality, Baker recognized a need to change the way their process wastewater was handled. Historically, all process wastewater had been hauled offsite to local municipalities leading to high (and increasing) disposal costs. On average, at least ten trucks were hauling wastewater from the facility on a daily basis. In addition to high costs, hauling all of the wastewater off-site greatly limited the facility’s ability to increase production and reduce whey transportation costs through whey concentration. Expanding production and introducing whey processing would significantly increase the amount of wastewater that the facility would create, as whey processing generates three times more wastewater than current cheese processing flows. Constructing and managing their own wastewater treatment plant (WWTP) seemed to be the only viable solution for Baker Cheese, but brought numerous other challenges with it, such as complying the very stringent phosphorus limits and aesthetic concerns.
In order to meet the current and future needs of the facility, The Probst Group worked with Excel Engineering and CD Smith to provide a new WWTP that could achieve phosphorus effluent concentrations to <0.4mg/L.
The WWTP includes expandable ultrafiltration (UF) membranes and an anoxic selector tank (used for nutrient control (Enhanced Biological Phosphorus Removal (EBPR)). The external UF membranes are a physical barrier which provides a reliable low solids effluent for Total Suspended Solids (TSS), compared to conventional solids-liquid separation technologies like clarification or Dissolved Air Flotation (DAF).
Reliable solids removal is imperative for ultra-low phosphorus limits, as biological solids contain 3-7% phosphorus. Additionally, a sludge digester was installed, reducing typical sludge yields by 30-50%.
To further reduce phosphorus and meet compliance requirements, Baker utilized a Water Quality Trade (WQT); the first approved Water Quality Trade in the State of Wisconsin.
To address the aesthetic concerns of Baker, a square concrete sludge tank was designed to “block” a circular concrete aeration basin, and a silo was used as a selector tank, allowing the WWTP to appear as part of the cheese plant.
