Date of Award

6-2018

Degree Name

MS in Civil and Environmental Engineering

Department/Program

Civil and Environmental Engineering

College

College of Agriculture, Food, and Environmental Sciences

Advisor

Tryg Lundquist

Advisor Department

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Advisor College

College of Agriculture, Food, and Environmental Sciences

Abstract

This thesis explores the treatment of municipal wastewater using pilot-scale raceway ponds and looks specifically at the capability of the raceways in removing BOD and nitrogen. Nine 33 square-meter algal raceway ponds were used to conduct research at the San Luis Obispo Water Resources Recovery Facility. Main objectives of this study were to increase the removal of total ammonia nitrogen (NH3-N plus NH4+-N) from municipal wastewater through increased assimilation and nitrification. Raceway ponds with CO2 addition were operated in series with an intermediate settling step and a total hydraulic retention time (HRT) of 4 days to measure the increase in nitrogen removal through assimilation by two rounds of algae growth. A single round of treatment with a 4 day HRT was also operated and compared to the two rounds. The two rounds of treatment and 1 round of treatment removed on average 36.6 mg-N/L and 35.2 mg-N/L of TAN, with respective standard deviations of 6.3 mg-N/L and 5.3 mg-N/L. No statistical significant difference was found between two treatment methods for TAN (mg-N/L) removal (t = -0.64, DF = 23.3, P =0.28), % TAN removal (t = -1.18, DF = 22.6, P = 0.25), and TAN (mg-N/L) of final effluent (t = 1.11, DF = 23.6, P = 0.28). Raceway ponds were aerated at night to keep nighttime DO from dropping to concentrations inhibitory to nitrification. The rates of nitrification with night aeration were measured. The nitrification rates were compared to a model based on Monod kinetics. The Monod model did not correspond with performance results of ponds.

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