Simultaneous removal of nitrogen and phosphorus from swine wastewater in a sequencing batch biofilm reactor

In this study, the performance of a sequencing batch biofilm reactor (SBBR) for removal of nitrogen and phosphorus from swine wastewater was evaluated. The replacement rate of wastewater was set at 12.5% throughout the experiment. The anaerobic and aerobic times were 3 h and 7 h, respectively, and the dissolved oxygen concentration of the aerobic phase was about 3.95 mg·L− 1. The SBBR process demonstrated good performance in treating swine wastewater. The percentage removal of total chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) was 98.2%, 95.7%, 95.6%, and 96.2% at effluent concentrations of COD 85.6 mg·L− 1, NH4+-N 35.22 mg·L− 1, TN 44.64 mg·L− 1, and TP 1.13 mg·L− 1, respectively. Simultaneous nitrification and denitrification phenomenon was observed. Further improvement in removal efficiency of NH4+-N and TN occurred at COD/TN ratio of 11:1, with effluent concentrations at NH4+-N 18.5 mg·L− 1 and TN 34 mg·L− 1, while no such improvement in COD and TP removal was found. Microbial electron microscopy analysis showed that the filler surface was covered with a thick biofilm, forming an anaerobic–aerobic microenvironment and facilitating the removal of nitrogen, phosphorus and organic matters. A long-term experiment (15 weeks) showed that stable removal efficiency for N and P could be achieved in the SBBR system.

Graphical AbstractA lab-scale sequencing batch biofilm reactor was used to treat swine waste water for simultaneous removal of nitrogen and phosphorus. The replacement rate of wastewater was 12.5%, COD/TN ratio was 11:1, anaerobic and aerobic times were 3 h and 7 h, respectively, and the DO of aerobic phase was about 3.95 mg·L− 1. A completed phosphorus release occurred at the anaerobic stage, and TN had a certain decline in the anaerobic process, indicating denitrification. The process demonstrated efficient treatment ability for swine wastewater. The effluent concentrations of COD, NH4+-N, TN, and TP were 131.1, 18.56, 37.62, and 1.08 mg·L− 1, respectively.Figure optionsDownload as PowerPoint slide