[Ammonia Removal Rate and Microbial Community Structures in Different Biofilters for Treating Aquaculture Wastewater]

Three MBBRs and three curtain type trickling filters (CTFs) with different carriers were operated in lab-scale simulated RASs. The characteristics of biofilms, ammonia removal rates and microbial communities in six reactors were compared with each other. Compared with the biofilms of MBBRs, the biofilms of CTFs were heavier and grew faster. The weight of biofilms on CTFs with carbon fiber carriers was the maximum (45.97 g·m^-2), and the ammonia nitrogen removal efficiency (86.76%) of this CTFs was higher than the other filters or reactors (61.96%~78.76%). In addition, the concentration of the accumulated nitrite in the carbon fiber CTFs was the lowest in all the six reactors. The microbial communities of biofilms in the six biofilters were evaluated by the high-throughput Illumina-MiSeq sequencing technology. The results showed that the microbial (bacteria and eukaryote) community in biofilms of CTFs was different from that in biofilms of MBBRs. At both bacteria and micro-eukaryote level, the species richness and biological diversity of biofilms in the trickling filters were higher than those in the MBBRs. On the contrary, the Simpson index of bacterial community in biofilms of MBBRs was higher than that in the trickling filters. In all the six biofilters, Nitrospira and Nakamurella were the dominated bacterial genera. Saprospiraceae was more abundant in CTFs than in MBBRs, but Comamonadaceae was enriched in the MBBRs. At the micro-eukaryote genus level, Rhabditida norank genus was more abundant in CTFs, while Chlorophyceae norank genus was more abundant in the MBBRs. The results provide useful information about microbial ecology that can be used for the application of CTFs in RAS.