Performance and kinetics of rotating drum biofilter aerobic simultaneous purifying SO2 and NOx.

The rotating drum biofilter (RDB) was investigated as a biological process for purifying SO2 and NOx. After 25 days of film hanging, the inlet concentration was less than 2800 mg·m-3, and the NOx inlet concentration was less than 800 mg·m-3, with greater than 90% desulphurisation and denitration efficiency. Bacteroidetes and Chloroflexi were the dominant bacteria in desulphurisation, while Proteobacteria were the dominant bacteria in denitrification. The sulphur and nitrogen in RDB were balanced when the SO2 inlet concentration was 1200 mg·m-3 and the NOx inlet concentration was 1000 mg·m-3. The best results were obtained SO2-S removal load was 28.12 mg·L-1·h-1 and NOx-N removal load was 9.78 mg·L-1·h-1. when SO2 concentration was 1200 mg·m-3, NOx concentration was 800 mg·m-3, and empty bed retention time (EBRT) was 75.36 s. The liquid phase dominated the SO2 purification process, and the experimental data fit better with the liquid phase mass transfer model. NOx purification was governed by the biological and liquid phases, with the modified biological-liquid phase mass transfer model fitting the experimental data better.

[Degradation of styrene by coupling ultraviolet and biofiltration].

Purification of styrene by ultraviolet (UV)-biofiltration was studied in this paper. The light source and the biofilm carrier were ozone producing lamp at 185 nm and the peat, palm fiber, porous acticarbon, respectively. Styrene inlet concentration was controlled between 320-583 mg x m(-3), and the removal efficiency remained above 95% after stabilization. The UV converted styrene into more soluble and biodegradable intermediates, such as alcohol, aldehyde and acid, thus the performance of biofilter can be improved. In the stable operation stage, the variation of inlet concentration did not affect the removal efficiency when the total residence time (TRT) was long, however, the inlet concentration obviously affected the removal efficiency when the TRT decreased. The removal load of coupling system increased linearly with increasing inlet load, and the removal efficiency was higher than 95% under a TRT of 102 s. When TRT was 68 s and the inlet load was low, the variation of removal load complied with the law described above, but it gradually deviated from the straight line and tended to stabilized at a certain value when the inlet load became higher than 30 g x (m3 x h)(-). If considering the fluctuation of styrene concentration only, the contribution rate of ultraviolet photolysis to styrene removal was greater than that of the biofilter, and the removal effect could be restored on the fourth day, after closing the system for ten days and restarting.

Dynamic model for nitric oxide removal by a rotating drum biofilter.

To illustrate the process of nitric oxide (NO) denitrifying removal by a novel rotating drum biofilter (RDB), a dynamic model has been developed and further validated. Based on the mass component profile of NO at the gas-liquid interface combined with a Monod kinetic equation, the model was used to depict the mass transfer-reaction process of NO in RDB, focusing on the concentration distribution of NO in the gas, liquid, and biofilm phases. The NO distribution equation on the biofilm carrier was thereby achieved, as well as a dynamic model for NO elimination in the test system. Additionally, effects of operating parameters such as inlet NO concentration and empty-bed residence time on NO removal efficiency were evaluated through a sensitivity analysis of the model. The model was then modified taking the absorption of NO by nutrition liquid in the bottom of RDB into consideration. The results showed that the simulated data agreed well with the experimental data. The model made it possible to simulate a relatively high NO removal efficiency by RDB.

[Microbial diversity analysis in rotating drum biofilter for nitric oxide denitrifying removal].

PCR-DGGE was applied to analyze the microbial communities in rotating drum biofilter (RDB) for nitric oxide denitrifying removal under anaerobic conditions. The 16S rRNA genes (V3 region) were amplified with two universal primers (338F-GC and 518R). These amplified DNA fragments were separated by parallel DGGE. The DGGE profiles of biofilm samples from different sections of RDB are similar and about sixteen types of microorganisms are identified in the biofilm samples. These results show that microbial diversity of RDB firstly increases but then decreases with the addition of Cu II (EDTA) and the increase of NO removal efficiency. However, the change of microbial community is not significant during the process. Eight major bands of 16S rRNA genes fragments from DGGE profiles of biofilm samples were further eluted from gel, re-amplified, cloned and sequenced. The sequences of these fragments were compared with the database in GeneBank (NCBI). The gene analysis of 16S rRNA showed that the major populations are Cytopahga-Flexibacteria-Bacteroides (CFB) group Bacteroides, beta -Proteobacterium, gamma-Proteobacterium and Clostridium sp.. In addition, denitrification is related with band G-5, G-6 and G-8. G-5 is affiliated with gamma-Proteobacterium. Both G-6 and G-8 are affiliated with beta-Proteobacterium.