| Volatile Organic Compounds (VOCs) is another kind of contamination junior to particles. They do great harm to human health and cause heavy pollution, however, are hard to control, especially for waste gases borne with low-concentration VOCs. So, an effective control approach is urgent. Biotreatment of air-borne contaminants offer an alternative to conventional air treatment technologies. Because of its advantages, such as simple equipment, low investments & operational spending and no secondary-pollution, it has received increased attention of scholars around the world.Two biofilters packed respectively with the activated carbon and rasching rings, inoculated with the activated sludge, which was domesticated by contamination, were used to purify the waste gases contained benzene and xylene vapor individually. And then another two kinds of ceramic pellets were filled into the filters and inoculated withxylene biodegraded bacteria-Bacillus firmus, which was screening by incubatorshaker experiment. The purifying performances of reactors were investigated. Moreover, the trickling flux and the N concentration in the trickling liquid's effects on biofilters' performance were thoroughly examined. Finally, the purifying efficiency of reactor packed with grains, in which the Bacillus firmus were immobilized, was examined.The results of trickling biofiltration experiments purging benzene vapor show that volume removal loadings of biofilters are increased along with the volume loadings, but the relationship between them are non-linear. The lower EBCT (empty bed contract time) is, the worse the reactors' performance is. The filter packed with activated carbon gain a better performance compared with the one packed with rasching rings, but the former own a much higher pressure drop when the fluid passes through it.The results of trickling biofiltration experiments purging xylene vapor show that the filters packed with rasching rings have low removal efficiency, and the performance of reactors are highly fluctuant.The results of high-effective trickling biofiltration experiments purging xylene vapor show that the biofilters inoculated with Bacillus firmus can get increased removal efficiency. For certain inlet concentration, when the EBAT (empty bed attained time) were 84.8s and 28.3s, the removal efficiency decreased along with the increase of drenching density of nutrient liquid. When the EBAT reduced to 17.0s, the drenching density of nutrient liquid had no significant effect on the performance of biofilters. At the EBAT of 84.8s and 28.3s, the biofilters can maintenance the removal efficiency no less than 97% when the inlet concentration was no more than 3000mg/m3. But, at the EBAT of 17.0s, the performance of biofilters deteriorated as the inlet concentration increased. For the biofilter 1 and 2, a removal efficiency of 80% and 82% can respectively be obtained when the inlet concentration was up to 3000mg/m3. Results show that higher removal efficiency can be obtained when the concentration of N in the nutrient liquid was increased. And, usage of NH4-N as the N source can cause the notified bacterium's accumulation in the biofliters. The pressure drop of the biofliters will be higher and higher because of the bacterium 's propagation, so some efforts should be made to control the biofilm's thickness. The measure results of biofilm's volatile suspended solid in the filters' unit show an uneven distribution of biofilm along the height in the biofilters. Compare with the 1# ceramic pellet, the 2# ceramic pellet owned a better inoculation and anti-impulse loadings ability, moreover, higher removal efficiency. Although the pressure drop of filter packed with 2# ceramic pellet are as twice as that packed with 1# ceramic pellet, there are low enough to be accepted.The results of Dynamic analysis show that one-stage biodegradation kinetic model coincide with experiment results well. And, the constant /Q changed along with the inlet concentration Cgi.For the biofilters inoculated with Bacillus firmus and were... |
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