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Phosphorus/Nutrient Removal Evaluation

Client: North Shore Water Reclamation District

Location: Gurnee, Illinois

The North Shore Water Reclamation District operates and maintains three wastewater treatment plants in northern Illinois with peak flow design capacities ranging from 28 to 47 mgd.

Wastewater treatment at each plant includes primary sedimentation followed by two-stage activated sludge treatment. The first stage of the activated sludge system is intended for carbonaceous BOD5 removal, while the second stage is intended to provide ammonia nitrogen removal through biological nitrification.

The State of Illinois has adopted interim phosphorus standards that will require plants to meet a 1 mg/L total phosphorus (TP) effluent limit. In addition to these standards, the State is in the process of developing water quality based nutrient standards that may impose more stringent effluent phosphorus limits and/or effluent total nitrogen (TN) limits in the future.

Donohue developed and utilized a calibrated BioWin process model to identify and evaluate feasible alternatives to achieve future low nutrient effluent limits. Alternative options, associated capital and projected operating costs, and non-economic factors were developed and evaluated for each plant, with the goal of developing a recommended approach, including phasing, for meeting both the interim TP and potential future TP and TN limits.