Start-up and Capacity Enhancement of a Partial Nitrification Pilot Reactor in Continuous Flow

Abstract

The continuous flow reactor was used to treat simulated ammonia nitrogen wastewater by inoculating the sludge after filtration and adding a suspended filler. Regulations of free ammonia (FA), free nitrous acid (FNA), and dissolved oxygen (DO) in the reactor were the key to achieving a successful start-up of the pilot scale nitrosation reactor. The results show that the enrichment of ammonium oxidizing bacteria (AOB) and the elimination of nitrite oxidizing bacteria (NOB) are achieved by adjusting the operational mode of high DO, low DO, FA, and FNA in the reactor operation. The nitrite production rate (NPR) in the reactor was 1.27 kg·(m3·d)-1 and the nitrogen accumulation rate (NAR) was stable at 98% at the end of the start-up period. qPCR was used to study the difference in the functional microorganisms (AOB, NOB) between the beginning and the end of the start-up period. The results show that the copy number of microbial AOB grew from 5.3×109 copies·mL-1 to 1.6×1011 copies·mL-1. The copy number of NOB decreased from 1.1×1010 copies·mL-1 to 1.2×109 copies·mL-1, because of the joint regulation of DO, FA, FNA to suppress NOB.