Studies On The Treatment Of Off-gases Containing BTX By The Combination Of Bacteria And Fungi

With the continuous improvement of people's living level, more and more attention has been paid to the danger of volatile organic compounds. Biotreatment of VOCs is a novel process which developed recently. the obvious advantage of this technology is that secondary-pollution will not be produced, and in low concentration, vulnerability microbial degradation of VOCs, Biotreatment is more economical than others.A new combined-bioreactor was used in this study. The combined-bioreactor consists of two zones, one bacteria zone and one fungi zone. An experiment for the VOCs treatment was carried out; Benzene, toluene and xylene (BTX) were main material in the off-gas. The factors which influent purifying performances of biofilter were investigated, including of different microorganism, BTX volume loading, BTX concentration, empty bed retention time (EBRT), environmental temperature , the time of recovery and the reactor pressure drop.The results show that the fungi zone gain a better performance compared with the bacteria zone, they were influenced by some factors which have a similar effect. Volume removal loadings of biofilters are increased along with the volume loadings, but rising trend is slowdown, finally, it will maintain a stable value. Different concentration of BTX has large influence to the reactors' performance. The high concentration of BTX is, the worse the reactors' performance is, but the relationship between them is non-linear. The longer EBCT more beneficial microbes to purify pollutants, but too long EBCT will lead to some adverse effects. The temperature has influence to microbial activity; the purifying efficiency in high temperature is higher than low temperature, the high temperature (31℃～41℃) is more conducive to the purifying efficiency, but it will consume more power. The combined-bioreactor has good shock resistance, two-day cease operations have little impact on the bioreactor, and seven days cease operations will have an obvious impact on the purification efficiency, but can be restored within two days. Keep the cycle of nutrient solution helps to renew the purifying efficiency.