Date Published: January 23, 2017
Publisher: Public Library of Science
Author(s): Jian Zhai, Zhu Wang, Peng Shi, Chao Long, Andrew C Singer.
To improve biofilter performance, the microbial community of a biofilter must be clearly defined. In this study, the performance of a lab-scale polyurethane biofilter for treating waste gas with low loads of nitrobenzene (NB) (< 20 g m-3 h-1) was investigated when using different empty bed residence times (EBRT) (64, 55.4 and 34 s, respectively). In addition, the variations of the bacterial community in the biofilm on the longitudinal distribution of the biofilters were analysed by using Illumina MiSeq high-throughput sequencing. The results showed that NB waste gas was successfully degraded in the biofilter. High-throughput sequencing data suggested that the phylum Actinobacteria and genus Rhodococcus played important roles in the degradation of NB. The variations of the microbial community were attributed to the different intermediate degradation products of NB in each layer. The strains identified in this study were potential candidates for purifying waste gas effluents containing NB.
Nitrobenzene (NB) is a typical hydrophobic (Henry’s law constant 2.41×10−6 MPa m3 mol-1 and other salient properties on the S1 Table) and refractory biodegradable volatile organic compound. NB is emitted mainly from explosives, aniline, dyes, pesticides, pharmaceutical manufacturing processes and waste water treatment plants. Because NB is relatively toxic and persistent in the environment, NB emissions are facing increasingly stringent environmental regulations. Biofilters were originally developed for odor pollution control due to their high efficiency, low energy consumption, low operating costs, and environmental-friendliness  and have recently been proven to be a promising technology for the treatment of volatile organic compounds (VOCs) at moderately high flow rates and low concentrations (<1000 ppm) [2–3]. This study demonstrated an efficient system for NB removal at low ILR values. The REs were always higher than 93% at different phases, and the slopes of EC/ILR were close to 1.0. Illumina MiSeq high-throughput sequencing technology was successfully applied to analyse the variations of the biodiversity and microbial community structure in these biofilms along the longitudinal direction of the biofilter. The increase of biodiversity from the bottom up was attributed to the increase of NB metabolic intermediate types. The microbial community structure affected the ecological function significantly and further influenced the performance of the biofilter. The sequencing data showed that the phylum Actinobacteria and genus Rhodococcus played key roles in the degradation of NB in the bottom layer. Source: http://doi.org/10.1371/journal.pone.0170417