The performance of the biofilm to treat benzene in waste gas

Biological treatment is a novel technology for contaminated airstreams in recent years. Biofilm is the key factor of gas contamination treatment in biofilter and biotrickling filter. In this investigation, when the benzene gas was treated by the biotrickling filter, a batch reactor was set up to measure the removing capability and CO_2 respiration rate of the piece of biofilm at different height. The results showed that the biofilm had different dry weight at different height in biotrickling filter. The dry weight of the biofilm at first layer was 35.9g·L~(-1), and the other two layers were lower than 20g·L~(-1). Similarly, the removing and respirating rate of the biofilm was decreased along the height of the biotrickling filter. In first layer, the removing rate was 35mg·L~(-1)·h~(-1) and the respiring rate of CO_2 was 146.4(mg·L~(-1)·h~(-1)), which were higher than the others. But the eliminating capability of dry weight per unit of biofilm in second layer was 2.11mg.h~(-1)·g, which was highest. And the eliminating capability in first layer was not so high and the producing rate of CO_2 was less than 20%. This research revealed that the eliminating capability could be enhanced by appropriate idle time with the condition of enough oxygen and water. In this study, the benzene eliminating capability improved 70% after 3 days' idling. However, the eliminating capability fell down after 5 days idling. And the mechanism of benzene biodegradation in biofilm was also discussed. Based on the result, it seemed that biodegradation of benzene and energy transforming processes existed at same time in biofilm. The higher of the benzen concentration, the more energy stored. The presence of energy storage substance decreased the eliminating capability of biofilm, but it increased its stability.