Effects of Influent C/N Ratios on Denitrifying Phosphorus Removal Performance Based on ABR-MBR Combined Process

Abstract

An ABR-MBR integrated reactor based on a combination of the anaerobic baffled reactor (ABR) with the microbial phase separation and membrane bioreactor (MBR) with high-effect entrapment was constructed and the circulation and interactivity of the combined process were examined by adding nitrate recycling and sludge reflux. By increasing the influent COD to adjust the COD/TN ratio, the influence of the mechanism on the denitrifying phosphorus removal performance under the condition of continuous-flow was investigated. The results showed that the average effluent concentration of soluble phosphorus under different influent C/N conditions were 0.22, 0.34, 0.39, 0.42, and 2.45 mg·L-1 and the low influent C/N ratio was beneficial to phosphate removal. When the influent C/N was 4.8-6.0, the average removal rates of COD, TN, and soluble PO43--P were more than 87%, 76%, and 93%. In addition, when the influent C/N ratio was 3.6-6.0, the removal of TN was proportional to the anoxic phosphorus uptake of ABR and conducive to the removal of TN after increasing the influent COD concentration. Higher C/N ratios of the influent improved the removal of TN at this stage. Finally, the C/N ratio of 6 was suggested to achieve the simultaneous removal of nitrogen and phosphorus.