title: Re-acclimation performance and microbial characteristics of a thermophilic biofilter for NOx removal from flue gas.
abstract: Currently, a novel chemical absorption-biological reduction (CABR) integrated process, employing Fe(II)EDTA as a solvent, is being under development to reduce the cost of NOx removal from flue gas. In this work, the NO removal profile, re-acclimation performance, and microbial characteristics in a thermophilic biofilter were investigated at the conditions typical to CABR process. The biofilter comprised of four layers of packing material with a surface area of 1200 m(2) m(-3). Experimental results revealed that the biofilter could remove 95 % of the fed NO at typical flue gas conditions. As the gas residence time varied from 90 to 15 s, the NO removal efficiency decreased from 100 to 56.5 % due to the NO mass transfer limitation. The longer period of the biofilter shutdown required more time for its re-acclimation. For example, after 8-day shutdown, the biofilter was re-acclimated in 32 h. Denaturing gradient gel electrophoresis analysis of PCR-amplified product showed that Pseudomonas, a group of denitrifier, was dominant in the biofilter. Because the Pseudomonas was abundant at the bottom layer of packed-bed, the bottom layer contributed to 60-70 % of the total NO removal. In addition, Pseudomonas gradually faded away along the gas flow path from the bottom to the top of biofilter, resulting in a significant decrease in NO removal at the other three packed-bed layers. These observed results will provide the process engineering and scale-up data with respect to the biofilter operations to help advance the CABR process to pilot-scale testing.
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Institute of Industrial Ecology and Environment, College of Chemical and Biological Engineering, Zhejiang University, Yuquan Campus, Hangzhou, 310027, China.
authors.forename: Shihan
authors.initials: S
authors.lastname: Zhang
authors.forename: Han
authors.initials: H
authors.lastname: Chen
authors.forename: Yinfeng
authors.initials: Y
authors.lastname: Xia
authors.forename: Jingkai
authors.initials: J
authors.lastname: Zhao
authors.forename: Nan
authors.initials: N
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Li
mesh_terms: D061808:Air Filters / Q000382:microbiology*; D058448:Biota; D005374:Filtration / Q000379:methods*; D005740:Gases / Q000737:chemistry*; D009569:Nitric Oxide / Q000302:isolation & purification / Q000378:metabolism*; D011549:Pseudomonas / Q000302:isolation & purification
chemical_list: D005740:Gases; D009569:Nitric Oxide