Wastewater Treatment In Kenosha T he treatment of waterborne waste in Kenosha began in 1938 when the City and Federal Public Works Administration agreed to construct a treatment plant. The plant was completed and put into service in 1940. The community’s share of the cost was provided from Water Utility funds because at that time, the City had no money set aside for that purpose. Primary Clarifiers To Our Customers K enosha is the gateway to Wisconsin. Located on the shores of Lake Michigan, a virtually unlimited supply of water, it is ideal for industry and recreation. The Kenosha Water Utility Provides water and wastewater service to nearly 110,000 people in the greater Kenosha metropolitan area. We have kept pace with the growth and needs of the community and have constructed water and wastewater facilities to adequately serve the area until the year 2020 and beyond. We are proud to explain to you how we protect Lake Michigan by our systematic treatment and control of wastewater. We wish you, our friends and customers, to know that behind the marvel of machines and materials, there are people, trained in their special fields, who devote their skill and experience in providing and protecting Kenosha’s greatest natural resource— WATER. Before discussing treatment capabilities of the original plant and its later expansions, it is necessary to understand that pollutants appear both as solids and in solution in the water. Relative strengths of wastewaters are measured by the amount of solids and the amount of oxygen required to stabilize the waste. This latter measure is called the biochemical oxygen demand (BOD). Stronger wastes, of course, require more oxygen than weaker ones. Added to these major measures of pollution are measurements for phosphates, mercury and other toxins, oils and greases, insecticides and pesticides, and a host of other discards of modern living. Treated Water Secondary Treatment Final Clarifier PRIMARY TREATMENT econdary treatment facilities were added in 1967, along with additional primary treatment capacity. Secondary treatment removes 90 to 95 percent of suspended solids and BOD, thus substantially reducing the amount of pollutants reaching Lake Michigan. Kenosha’s type of secondary treatment is an activated sludge process wherein bacteria and microorganisms use the pollutants as food in a carefully controlled biological environment. T he original treatment plant consisted merely of controlling flows to allow for the settling of solids carried into suspension. This is called primary treatment and plants of this type have a capability to remove only about 50 percent of the suspended matter and 30 percent of the BOD. Thus until 1967, a major portion of pollutants were discharged to the lake as treatment plant effluent. The rest of the treatment process consisted of provisions for removing solids from the flow. These were held for a period of time and digested to change them from an unstable and degradable form to one which could be dried for disposal on farm land or in a landfill without creating a nuisance. S The most recent expanded additions, completed in 1985, are designed for an average daily flow of 28 million gallons per day (MGD). Capacity is provided for a maximum daily flow up to 68 MDG with a peak hourly capacity of 85 MGD. Activated Sludge Filter Press The expanded facility has allowed the Kenosha Water Utility to meet or exceed the Environmental Protection Agency and Department of Natural Resources effluent limitations 30 milligrams per liter of BOD and suspended solids (SS) and 1 milligram per liter of phosphorous (P) for a design population of 135,000. Administration and Maintenance Buildings Raw Wastewater Pump Station Grit Removal Primary Clarifiers Activated Sludge Process (aeration tanks and blowers) Final Clarifiers and Activated Sludge Pumps Aerial Photograph The Kenosha Wastewater Treatment Facility is designed to treat an average daily flow of 28 million gallons per day. Kenosha has treated its wastewater since 1940. The administration building shown on the cover was part of the original facility. Chlorination System and Chlorine Contact Tanks Sludge Handling System (thickening, digestion, and dewatering) Pickle Liquor Building Piping Tunnel Major Process Elements Kenosha plant Sludge Storage Pumping—average flow of 22 million gallons per day. Grit Removal—removes 54 cubic feet per day of inorganic sand, gravel and other heavy material. N Primary Settling—produces 50,000 gallons of sludge per day. Aeration—requires 18 million cubic feet per day of compressed air. Anaerobic Digestion—produces 150,000 cubic feet per day of methane gas used to power pump engines. 7835 Third Avenue Kenosha, Wisconsin Sludge Thickening—uses air floatation to thicken waste activated sludge from 1 percent solids to 4 percent solids to conserve digester space. Sludge Dewatering—employs plate and frame filter presses to dewater digested sludge to 40 percent solids. Nearly 80 tons of sludge per day are hauled to a solid waste landfill to be used as top cover. Final Clarification—separates the activated sludge from the final effluent through sedimentation. Approximately 7.6 million gallons of sludge gets returned to the aeration basins. Disinfection—final effluent travels through chlorine contact tanks for disinfection prior to being dechlorinated and discharged 1,200 feet into Lake Michigan.