A new type of zeolite-suspended packing was developed by using zeolite as an important raw material, which was then used to start the zeolite moving bed biofilm reactor (ZMBBR). ZMBBR was compared with the ceramsite moving bed biofilm reactor (CMBBR) packed with ordinary ceramsite-suspended packing to investigate the different nitritation performance. The results showed that stable nitritation was successfully achieved in two reactors by the inhibitory effect of free ammonia (FA), and both of their nitrite accumulation rates (NAR) reached 90%; due to the adsorption of zeolite to ammonium, ZMBBR relieved the inhibition of FA on AOB faster than CMBBR and achieved nitritation earlier; CMBBR and ZMBBR could maintain long-term stable nitrosation when ρ(NH4+-N) was 350 mg·L-1 and 1050 mg·L-1 and NPRAVG was 0.43 kg·(m3·d)-1 and 1.26 kg·(m3·d)-1, respectively, and ARECMBBR=82.21% and AREZMBBR=88.85%. In the process of the influent ρ(NH4+-N) gradually increasing from 250 mg·L-1 to 1250 mg·L-1, the maximum nitrite production rate (NPR) of CMBBR was 0.5634 kg·(m3·d)-1; when ρ(FA) reached 166 mg·L-1 at the influent ρ(NH4+-N) of 750 mg·L-1, CMBBR broke down for the heavy inhibition of FA. The maximum NPR of ZMBBR was 1.800 kg·(m3·d)-1, and the performance of ZMBBR was getting worse after the ρ(FNA) reached the peak value of 1.9611 mg·L-1 at the influent ρ(NH4+-N) of 1250 mg·L-1. Subsequently, the ρ(FA) of ZMBBR reached 158 mg·L-1 rapidly, the NPR dropped significantly to 0.9028 kg·(m3·d)-1, and the performance of ZMBBR became significantly worse. It was demonstrated by high-throughput sequencing analysis that the dominant strain of ZMBBR and CMBBR was Nitrosomonas_europaea, and the relative abundances of N._europaea in ZMBBR and CMBBR were 11.15% and 10.92%, respectively.
Keywords: ceramsite; high-throughput sequencing; moving bed biofilm reactor (MBBR); nitritation; zeolite-suspended packing.