Microbial communities in the functional areas of a biofilm reactor with anaerobic-aerobic process for oily wastewater treatment.Microbial communities in the functional areas of biofilm reactors with large height-diameter ratio using the anaerobic-aerobic (A/O) reflux process was investigated to treat heavy oil refinery wastewater without pretreatment.  In the process, chemical oxygen demand (COD) and total nitrogen (TN) removal reached 93.2% and 82.8%, and the anaerobic biofilm reactor was responsible for 95% and 99%, respectively. 
Biofilm reactor
Microbial communities in the functional areas of a biofilm reactor with anaerobic-aerobic process for oily wastewater treatment.Microbial communities in the functional areas of biofilm reactors with large height-diameter ratio using the anaerobic-aerobic (A/O) reflux process was investigated to treat heavy oil refinery wastewater without pretreatment. 
Anaerobic-aerobic process