Effects of temperature on nutrient removal performance of a pilot-scale ABR/MBR combined process for raw wastewater treatment

For the purpose of achieving relatively high efficiency, low energy demands, and easy maintenance for nutrient removal, the performance of a pilot-scale biological nutrient removal process consisting of anaerobic baffled reactor and membrane bioreactor has been evaluated for 301d in treating two kinds of raw wastewaters. The results showed that the process enabled a relatively stable and high performance in both organics and nutrient removals, and high quality effluent was achieved under temperature of 25 +/- 5 degrees C. When the ambient temperature were 10 +/- 5 and 35 +/- 5 degrees C, average COD, NH4+-N, TN, and TP removal efficiencies of both kinds wastewaters were more than 88, 87, 70, and 75%, respectively. Analysis of the results by fluorescence in situ hybridization showed that ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, and phosphorus-accumulating organisms were always the enriched micro-organisms in the process during the change of temperature, ensuring the efficient nutrient removal under ambient environment with low energy exhaustion.