Effects of Different Nitrite Generation on the Short-cut Nitrification Denitrifying Phosphorus Removal Granules System

Abstract

To explore the effects of nitrite generation on the system of short-cut nitrification denitrifying phosphorus removal granules, nitrite was produced continuously and intermittently, under continuous and intermittent aeration, in two groups of SBR reactors of the same size. The effects of nitrogen and phosphorus removal, physical characteristics of the sludge, and microbial community structure were investigated. Nitrite was consumed immediately after intermittent production, with better and more stable nitrogen and phosphorus removal performance. In particular, the average rate of TN removal was 92.07% after 72 days. The utilization efficiency of the carbon source (by P/COD) was concentrated at 0.21-0.22 mg ·mg-1, to ensure full utilization of the carbon source and to further promote denitrification and phosphorus removal. Particle sizes were uniform and showed concentrated distribution, with particles exhibiting regular shapes and clear boundaries. Microbial community analysis showed that the abundance and diversity of microbial communities were higher in the intermittent nitrite system and more enriched in DPAOs genera (Dechloromonas and Pseudomonas). The combination of DPAOs genera and Nitrosomonas resulted in a dynamic balance and stable operation of the short-cut nitrification and denitrifying phosphorus removal system.