Sheboygan Regional Wastewater Treatment Facility

        Secondary Treatment - Activated Sludge Process

Biological Nutrient Removal

In 1999, two aeration basins (50 ft. x 100 ft. x 26 ft.) were modified to allow for Biological Nutrient Removal. The BNR process goal is to remove phosphorous without the addition of expensive chemicals. Baffle walls were installed to direct the flow into an N shaped path that increased the detention time in the basin, thereby creating anoxic conditions for the specialized bacteria required in the BNR process. Eight submersible mixers were added to each basin to keep the solids from settling in the basin. Detention time is 3.75 hours at average daily flow.


Aeration Basins

The four remaining aeration basins (50 ft. x 100 ft. x 26 ft. deep) each contain 1,500 submerged fine bubble diffusers. The high volume of air required is generated by two Turblex® variable vane turbine blowers powered by 350 horsepower premium efficiency motors. The blowers provide the mixing and oxygen necessary to maintain the Activated Sludge process. This process consists of providing the right environment for the bacteria and other microorganisms that consume the organic matter in the wastewater.


The Dissolved Oxygen(DO) concentration in the aeration basins is monitored and controlled using MJK® DO probes. Plant operators monitor the aeration process to ensure that the proper DO concentrations are maintained to provide the ideal environment for proper wastewater treatment. Detention time in the aeration basins is 7.5 hours at average daily flow.