Application of a moving bed biofilm reactor for tertiary ammonia treatment in high temperature industrial wastewater

This study examines the use of a moving bed biofilm reactor (MBBR) as a tertiary treatment step for ammonia removal in high temperature (35-45 °C) effluents, and quantifies different phenotypes of ammonia and nitrite oxidizing bacteria responsible for nitrification at elevated temperatures. Bench scale reactors operating at 35 and 40 °C were able to successfully remove greater than 90% of the influent ammonia (up to 19 mg L^-1 NH₃-N) in both the synthetic and industrial wastewater. No biotreatment was observed at 45 °C, although effective nitrification was rapidly recovered when the temperature was lowered to 30 °C. Using qPCR, Nitrosomonas oligotropha was found to be the dominant ammonia oxidizing bacterium in the biofilm for the first phases of reactor operation. In the later phases, Nitrosomonas nitrosa was observed and its increased presence may have been responsible for improved ammonia treatment efficiency. Accumulation of nitrite in some instances appeared to correlate with temporary low presence of Nitrospira spp.