[Gaseous phenol removal in a bio-trickling filter].

The performance of a bio-trickling filter (BTF) for treatment of phenol, a model pollutant, was presented. Influences of factors on phenol removal efficiency were studied. The BTF exhibited a high removal efficiency for phenol. The experimental results showed that the phenol efficiency reached 99.5% and kept 98% in the long-term run. The optimal residence time, pH value and spray density were 20.6 s, 7.0 and 1.67 m(3) x (m(2) x h)(-1), respectively. The microbial community structures in the bio-trickling filter for phenol removal were assessed by PCR-DGGE. Based on the 16S rDNA sequence data,results showed that the predominant bacteria for degradation of phenol were Polaromonas sp., Acinetobacter sp., Acidovorax sp., Veillonella parvula and Corynebacterium sp., GC-MS was used to detect component of BTF's outlet gases and pyruvic acid (CH3COCOOH) was found as one kind of intermediates of phenol degradation. Then one possible biodegradation pathway of phenol was inferred.

[Mechanism and performance of styrene oxidation by O3/H2O2].

It can produce a large number of free radicals in O3/H2O2, system, ozone and free radical coupling oxidation can improve the styrene removal efficiency. Styrene oxidation by O3/H2O2 was investigated. Ozone dosage, residence time, H2o2 volume fraction, spray density and molar ratio of O3/C8H8 on styrene removal were evaluated. The experimental results showed that styrene removal efficiency achieved 85.7%. The optimal residence time, H2O2, volume fraction, spray density and O3/C8H8 molar ratio were 20. 6 s, 10% , 1.72 m3.(m2.h)-1 and 0.46, respectively. The gas-phase degradation intermediate products were benzaldehyde(C6H5CHO) and benzoic acid (C6H5 COOH) , which were identified by means of gas chromatography-mass spectrometry(GC-MS). The degradation mechanism of styrene is presented.

[Mechanism and performance of a membrane bioreactor for treatment of toluene vapors].

The performance of a membrane bioreactor for treatment of toluene as a model pollutant is presented. Effects of toluene inlet concentration, residence time, spray density and pH of liquid phase on the toluene removal rate were evaluated. The experimental results showed that the toluene removal efficiency reached 99%. The optimal pH, residence time and spray density were 7.2, 6.4 s and 2.5 m3 x (m2 x h)(-1), respectively. The gas-phase biodegradation intermediate products were acetaldehyde acid (C2H2O3) and vinyl formic acid (C3H4O2), which were identified by means of gas chromatography/mass spectrometry (GC/MS). The mechanism of toluene degradation using a membrane bioreactor can be described as the combination of mass transfer from hollow fiber membrane to biofilm and biological degradation. Toluene (C6H5CH3) and oxygen diffused from the gas phase to the wet layer of the biofilm and were then consumed by the microbial communities. Toluene was oxidized to the intermediate organic products such as acetaldehyde acid (C2H2O3) and vinyl formic acid (C3H4O2), and the intermediate products were then converted to CO2 and H2O through continuous biological oxidation reactions.