Enhanced Simultaneous Nitrogen and Phosphorus Removal Performance of the AGS-SBR Reactor Based on the Effects of the C/N Ratio and Microbial Community Change

In recent years, the development of AGS technology will likely lead to a new direction in wastewater treatment development in the future. Traditional sewage treatment technology has been unable to meet the increasingly strict quality standards of wastewater treatment and limited land requirements. AGS technology may be a new method to replace traditional sewage treatment technology. However, the stable operation of AGS technology is a major obstacle to the popularization and development of this technology. The C/N ratio is an important parameter affecting the stability and simultaneous nitrogen and phosphorus removal of AGS technology. In order to enhance the nitrogen and phosphorus removal capacity of a low-load aerobic granular sludge SBR (AGS-SBR) system, changes in the morphology, EPS, and simultaneous removal of organic matter, nitrogen, and phosphorus in the AGS system were studied by regulating different C/N ratios (20, 15, 10, 5). The changes in the microbial community in the system were deeply analyzed by high-throughput sequencing technology. The results showed that different C/N ratios have a significant effect on the nitrogen removal rate of AGS but have little effect on the removal rate of organic matter and phosphorus. When the C/N ratio was reduced to 10, it was conducive to the stability of the low-load AGS-SBR system. An effective C/N ratio promoted the secretion of EPS by microorganisms, and the increase in the PN value contributed to the stability of the granular sludge, which became smooth and compact. The main functional genus in the system were norank_f__Saprospiraceae, Tetrasphaera, Ellin6067, and Pseudomonas. In addition, the simultaneous nitrogen removal performance of the system was significantly improved.