WASTEWATER FLOW STUDIES AT THREE FOOD INDUSTRIES: BENEFITS, CHALLENGES, AND COSTS

Flow and waste characteristic studies provide useful information during the planning phase for wastewater treatment plant improvement projects. Such studies may point to the need to expand or add treatment processes, suggest the elimination of treatment processes, or confirm existing treatment processes are adequate to treat the existing wastewater flows. Without this data, the basis of design for plant modifications is not well defined, and the selection and design of treatment processes may be difficult. This paper discusses three recent projects at food processing industries that utilized temporary flow monitoring and wastewater sampling to determine important wastewater characteristics prior to designing improvements to the existing wastewater pretreatment plants (WPTPs).Facility No. 1 has a separate cheese production plant and an ethanol production plant. The total flow and loading from the combined plants was known, but the proportion of flow and organic loading from each facility was unknown. Planning efforts were being undertaken to determine how best to expand the WPTP to accommodate the anticipated production growth over the next several years. The study was useful in determining an approximate proportion of flows and loadings from the two production plants, which added considerable value during the wastewater pretreatment planning effort.Facility No. 2 is a meat processing facility. The existing WPTP was operating beyond its design capacity, and the business was anticipating significant growth over the next several years. There was no WPTP influent flow and loading data available, and there was little confidence in the accuracy of the WPTP effluent data. The main goals of the study were to determine actual design flows and to evaluate the need for flow equalization facilities for the upgraded WPTP. The results of the study were used to justify a reduced project scope, which saved the project hundreds of thousand of dollars.Facility No. 3 was also a meat processing facility. Total wastewater flows were believed to be approximately 650,000 gpd based on historical water use records. However, because of the uncertainty surrounding the water losses through production, actual wastewater flows were not known to any degree of certainty. In addition, the existing pretreatment facilities were undersized, and pH control was required to meet the plant's permit conditions. The study indicated that actual wastewater flows were reasonably close to the estimated flows based on water use records. This confirmation of design flow data significantly reduced the overall cost of the WPTP upgrade.