title: Performance and influence factors of completely autotrophic nitrogen removal over nitrite (CANON) process in a biofilter packed with volcanic rocks.
abstract: Completely autotrophic nitrogen removal over nitrite (CANON) process was considered as one of the most efficient and economical nitrogen removal processes, which was suitable for treating wastewater with low ratio of carbon to nitrogen. In this study, an enlarging start-up strategy for CANON process was proposed, and a 40-L CANON reactor was successfully started by seeding 2-L mature biofilm containing both aerobic ammonia-oxidizing bacteria (AerAOB) and anaerobic ammonia-oxidizing bacteria (AnAOB). The effects of dissolved oxygen (DO), ammonia loading rate and the ratio of air inflow to water inflow (Qair/Qwater) on nitrogen removal performance were investigated. The distribution of AerAOB and AnAOB was analysed using fluorescence in situ hybridization (FISH) technique. The system reached a maximum NRR of 3.11 kg N m(-3) d(-1) with a removal efficiency of 89.5%, and the average value in steady state was 2.42±0.26 and (83.07 ± 6.89)%, respectively. Analysis of influence factors showed the important role of high DO (around 5 mg L(-1)), for the high-rate nitrogen removal, and the Qair/Qwater should be controlled at 28-40 for stable operation. FISH results suggested that AerAOB and AnAOB predominated in the reactor, with proportions of 46.8% and 39.3%, respectively. This study demonstrated that the biofilter operated with high effluent DO was a feasible setup for CANON process.
authors.affiliation: a Key Laboratory of Water Quality Science and Water Environment Recovery Engineering , Beijing University of Technology , Beijing 100124 , People's Republic of China.
authors.forename: Yuhai
authors.initials: Y
authors.lastname: Liang
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Zhang
authors.forename: Huiping
authors.initials: H
authors.lastname: Zeng
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
mesh_terms: D052818:Autotrophic Processes; D005240:Feasibility Studies; D005374:Filtration / Q000295:instrumentation*; D017404:In Situ Hybridization, Fluorescence; D009573:Nitrites; D009584:Nitrogen / Q000302:isolation & purification*; D018508:Water Purification
chemical_list: D009573:Nitrites; D009584:Nitrogen
keywords: CANON; DO; FISH; nitrogen removal; start-up