About the Wastewater Treatment Facility

The Wastewater Facility provides for the cost effective treatment of all wastewater discharged into the City of Ripon sanitary sewerage system. The wastewater (ie: used water) is cleaned in accordance with strict State and Federal regulations so that the cleaned water can be returned back to nature and used again as part of the natural water cycle process.   

Built to Improve Water Quality:
The upgraded and expanded wastewater treatment facility began operation in February 2003. Costing $7.5 million, the new facility currently treats 1.3 million gallons of wastewater per day containing 3,900 pounds of Biochemical Oxygen Demand (BOD) pollutant loading. The facility is designed for an average daily flow of 1.8 million gallons per day containing 4,500 pounds of BOD. The capacity is sufficient to allow for residential and additional industrial expansion as projected during the planning phase of the new facility. The new facility was constructed with 77% funding from Wisconsin’s Clean Water Fund Loan Program and 23% from facility cash reserves. 

The current Wisconsin Pollution Elimination Discharge Permit granting the City of Ripon to discharge its cleaned water to Silver Creek allows a maximum average discharge concentration of 10 milligrams per liter (mg/l) of BOD, 10 mg/l TSS (Total Suspended Solids), 1 mg/l of Phosphorus, and 5 mg/l of Ammonia Nitrogen in the winter months and 3 mg/l in the summer months. Since 2003, the City has met these stringent water quality limits. In doing so, it has significantly improved the local and state water environment. 

New water quality standards were imposed on the City in October 2020 and included even stricter effluent limits for Ammonia Nitrogen, Phosphorus, Chlorides, E. Coli & B.O.D.. The new treatment facility was specially designed to meet the additional requirements. 

A variety of physical and biological systems remove pollutants and impurities from the wastewater producing an effluent, which is 99% clean water. Wastes (sludge), removed from wastewater in the production of clean water, are further processed to produce bio-solids, which is ultimately used as fertilizer for certain farm crops. 

All of Ripon’s wastewater enters the treatment facility via a 36-inch pipe nearly 30 feet below the ground where it is pumped about 60 feet vertically to an automatic screening machine. This machine removes inorganic materials (wood, plastic, rubber, stones, etc.) that are larger than ¼-inch in diameter. The material is automatically washed, compacted and bagged (2 Cu. Ft. per day) and disposed of at a licensed landfill. 

After this continuous process, the wastewater flows by gravity a short distance to two 1 million gallon oxidation (aeration) ditches where almost all of the organic pollutants (B.O.D., Phosphorus, and Ammonia Nitrogen) is removed with biological processes utilizing naturally occurring micro-organisms (bacteria and protozoans). The micro-organisms absorb (eat and digest) the organic matter creating a product called mixed liquor (sludge). 

Being a continuous process, the oxidation ditches overflow the mixed liquor in contained channels and pipes to two 0.4 million gallon clarifiers. The sludge solids from the mixed liquor settles to the bottom of the 70-foot diameter clarifiers and the clarified liquid (water) overflows the weirs located at the top of each clarifier. 

About 50% of the sludge solids are pumped back to the oxidation ditches to maintain the correct food to micro-organism ratio for effective activity in that process. The remaining 50% is pumped to two 0.0234 million gallon aerobic digesters for additional treatment before the solids are thickened and applied on land as biosolids fertilizer for certain farm crops. The water produced in the clarifiers is collected separately and piped by gravity to tertiary filters, which screens out fine particulate matter that may still be in the water after the clarifier process. 

After the indoor tertiary filtration process, the water is sampled, metered, disinfected by ultraviolet scanning, and aerated to a minimum 7.0 mg/l dissolved oxygen content before discharge to Silver Creek. Numerous daily laboratory tests are performed on flow proportional samples of the effluent discharge (water) to help insure and confirm that it meets all regulatory agency requirements. Unannounced inspections/testing by Wisconsin DNR and others are sporadically performed on-site to also help ensure integrity of clean water discharge.