Improving the Culture: Rapid Deployment of a New Pretreatment Facility for a Yogurt Producer

Yogurt production is a process that is highly regulated with respect to the need to frequently clean and maintain facilities and equipment. These activities, along with the occasional wasting of product, result in very high strength wastewater discharges. Typically, this will require that large yogurt production facilities engage in wastewater pretreatment prior to discharge to publicly owned treatment works (POTW).A yogurt production facility in West Jordan, Utah recently completed a new pretreatment facility to replace a facility that had been ineffectual at treating wastewater to a level that was acceptable to the receiving POTW. Poor performance of the old pretreatment plant was a serious concern for the POTW, since the resulting biological load was overwhelming the POTW's treatment processes. As a result of the poor pretreatment performance, the POTW had enacted high surcharge tariffs on the yogurt production facility's wastewater discharges, along with fines and a moratorium on future plant expansions.Due to an expanding yogurt market, the yogurt production facility wanted to expand, but was unable to do so without a new pretreatment plant. In order to afford a new pretreatment plant, it would have to be justified by expansion of yogurt production. In order to complete either project, it was important for the POTW and the yogurt production facility to come to an agreement to allow both projects to proceed.The project agreement required careful timing of both projects to allow them to be economically sustainable and acceptable by the parties involved. The complexity of the wastewater project resulted in a project schedule that would be far longer than acceptable using typical construction and procurement techniques. Therefore, the Design/Build process was used. This reduced the construction schedule significantly, which resulted in a condensed construction process of 111 days from ground breaking to processing water.The new pretreatment facility is designed to treat 550 gpm with a BOD of 2,800 mg/L. The discharge limit agreed to between the POTW and the yogurt facility would result in a BOD of 300 mg/L at the design flow. In order to meet the discharge requirements, a Moving Bed Bioreactor (MBBR) facility was constructed, with Dissolved Air Flotation (DAF) for primary and secondary sedimentation. In order to improve process results and to provide storage in case of mechanical failures, a large equalization system was provided. This system had the added benefit of eliminating the use of caustic and acid at the facility, which had previously resulted in approximately $1,000,000 in annual operating expenditures in the old pretreatment facility. Currently, the new pretreatment facility is producing about half of the design flow, but is discharging much higher wastewater strengths than anticipated in the design phase. The plant has been able to exceed the anticipated performance, with the plant effluent typically around 150 mg/L BOD.