Study on nitrogen removal mechanism of the micro-pressure double-cycle reactor

To explore the reasons for the excellent denitrification performance of the Micro-pressure double-cycle reactor (MPDR), the nitrogen removal mechanism of the reactor in the treatment of municipal wastewater was studied. Through analysis of flow simulation and dissolved oxygen (DO) distribution, it was determined that the reactor had a macroscopic biochemical reaction environment for simultaneous nitrification and denitrification (SND) because of the special structure of reactor. The result of sewage treatment showed that the average removal rates of COD, NH4+-N, TN, TP were 92.29%, 96.64%, 73.6% and 91.66% respectively, and the SND rate was 60.9%. Dechloromonas, Thermomonas, Micropruina, Tetrasphaera, etc. for nitrogen and phosphorus removal existed in the reactor at the same time to explain the excellent performance of the system. PICRUSt2 showed that the metabolic pathways related to nutrient degradation in the reactor were highly active and the abundance of denitrification functional genes was higher in the central zone and lower in the peripheral zone. The research results not only perfected the basic theory of the reactor, but more importantly, provided theoretical and technical support for the further application of the reactor.