Microbial Ecology of a Completely Autotrophic Nitrogen-Removal Over Nitrite (CANON) Biofilm Reactor Enriched From Native Activated Sludge
Abstract:The Completely Autotrophic Nitrogen-removal Over Nitrite (CANON) process is the biological conversion of ammonia to dinitrogen gas using nitrite as an electron acceptor in a single stage, completely autotrophic, and oxygen-limited condition. The CANON process requires intermittent aeration resulting in about 60% reduction of oxygen demand and 100% reduction of external carbon. Despite of the advantages, the application of the CANON process to the fullscale wastewater treatment is rather limited primarily due to the lack of knowledge in microbial ecology of the CANON system and experiences in the enrichment of the responsible microorganisms. One of the essentials to achieve successful enrichment of the CANON process includes a microbial harmony of the two key microorganisms (i.e., aerobic ammonium-oxidizing bacteria (AOB), and anaerobic ammonium-oxidizing bacteria (AMX)). Therefore, overall goal of this study was to establish a stable CANON process with local activated sludge and track and control the three major bacterial members (AMX, AOB, and nitrite-oxidizing bacteria (NOB)) that contribute to high N removal performance. Over one year of lab scale CANON moving bed biofilm reactor (MBBR) operation, Nitrosomonas eutropha related AOB, C. Brocadia sp. 40 related AMX were dominant based on the Denaturing Gradient Gel Electrophoresis (DGGE) results. NOB were not abundant in the CANON reactor (<0.05%) based on the quantitative polymerase chain reaction (qPCR). Further, it was confirmed that filamentous-like bacteria belonging to Chlorobi/Bacteroidetes superfamily were also highly enriched, possibly playing a crucial role in biofilm structure. The results demonstrated the successful enrichment and operation of a CANON bioreactor from native active sludge.
Document Type: Research Article
Publication date: 2010-01-01
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