Continuous fed-batch alternating aerobic and anoxic system for biodegradation of Decontaminating Solution 2 with high nitrogen content

Abstract

A continuous fed-batch alternating aerobic and anoxic (CFBAAA) activated sludge system was developed for biodegradation of the US Army’s Decontaminating Solution 2 (DS2). The high nitrogen content in DS2 (approximately 28.5% by weight) necessitated a new nitrification/denitrification process scheme for biological nitrogen removal. Nitrification, conversion of NH4+ from the DS2 degradation to NO3−, is accomplished simultaneously along with the DS2 degradation under aerobic conditions, and denitrification, conversion of accumulated NO3− to N2, is achieved under anoxic conditions in which the air supply is ceased. A one-day cycle with 16 h air-on and 8 h of air-off was used.Overall, the CFBAAA system could achieve COD removal of >97% and TN of >99% at a hydraulic retention time of 16 d, when 1% DS2 (equivalent to 17,500 mg COD L−1 and 2850 mg N L−1) was fed. In addition, due to its cyclic operation mode, the CFBAAA system could reduce 1/3 of electricity consumption compared to the conventional activated sludge system.