Pyrosequencing Analysis of Bench-Scale Nitrifying Biofilters Removing Trihalomethanes

Biofilm communities in four bench-scale nitrifying biofilters degrading drinking water-regulated trihalomethanes were analyzed by next-generation high-throughput 454 pyrosequencing. On average, the bacterial communities were dominated by Nitrosomonas (69%), Nitrobacter (14%), and Chitinophagaceae (9%) with the dominant bacterial operational taxonomic unit (OTU) related to the ammonia-oxidizing bacteria (AOB) Nitrosomonas oligotropha. Even though ammonia-oxidizing archaea (AOA) have been reported in drinking water systems, the current study generated no PCR product or a very low yield of detectable Archaea amplicons, which may be attributed to biofilter operating conditions [e.g., 4 mg N/L TOTNH3 (sum of ammonia-nitrogen and ammonium-nitrogen)] that promoted AOB compared with AOA growth. Spatially within a given biofilter (influent to the effluent), OTU relative abundance significantly changed such that Nitrosomonas relative abundance decreased and Chitinophagaceae and Nitrobacter relative abundance increased.