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Nutrient management control regulation and preparedness of a northern Colorado wastewater treatment plant




Venkatapathi, Keerthivasan, author
Omur-Ozbek, Pinar, advisor
Carlson, Kenneth, committee member
Reardon, Kenneth, committee member

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Excessive nutrients in wastewater treatment plant (WWTP) effluents instigate eutrophication of receiving water bodies. Colorado Department of Public Health and Environment (CDPHE) adopted nutrient management control regulation, also known as regulation 85, to moderate the nutrients released by point sources such as the WWTP effluents. City of Loveland WWTP was selected as the study plant to determine a new treatment process configuration to meet the new limits of total phosphorus < 1 mg/L and total inorganic nitrogen < 15 mg/L in the effluent. BioWin, a windows based modeling software, was used to model and simulate the City of Loveland WWTP. Existing activated sludge step feed process configuration was modeled along with proposed anaerobic, anoxic, oxic (A2O) process for design influent flow of 10 MGD and 5-stage Bardenpho process for future flow of 12 MGD along with A2O process. Existing configuration was modeled to establish the accuracy of BioWin. 5 stage Bardenpho process modeling indicates that higher design HRT of 2 days for anaerobic, 4 days for anoxic, 6 days for aerobic, 4 days for secondary anoxic and 1 day for reaeration has better treatment removal efficiency for nutrients with methanol dosage of 250 gal/d and 1Q internal recycle. Model simulations for A2O process reveals that aerobic reactor to anaerobic reactor volume ratios from 3 to 4 and aerobic reactor to anoxic reactor volume ratio of 2.2 along with internal recycle of 1Q has the better nutrient removal efficiency for design flow of 10 MGD. For 12 MGD influent flow, volume of reactors was increased by 20% to compensate for 20% increase in the flow. Previously mentioned reactor volume ratios are feasible for 12 MGD influent flow with volume ratios of 3 and 4 for aerobic to anaerobic reactors and volume ratios of 1.8 and 2 for aerobic to anoxic reactors. Modeling results indicates that increasing the reactor volume ratio for increased flow can result in better treatment for removal of nutrients with a conservative volume, reducing the operational and maintenance cost.


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BioWin modeling


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