Studies On The Treatment Of Off-gases Containing BTX By Biofilter Process With Fungi

Volatile Organic Compounds (VOCs) is a kind of contamination which harmful for human beings and environment. This problem has been paid attention more seriously. Biotreatment of VOCs is a new technology which developed recent years. For this technology, there are many advantages, such as simple equipment, low investments and operational spending and no secondary-pollution.In this study, some ceramic pellets (CP),some activated carbon(AC)and mixture of ceramic pellets and activated carbon(CP/AC)were used for microorganism medium in biofilter respectively. Benzene, toluene and xylene (BTX) were the off-gas, used biofilter process with fungi treatment BTX. Inoculated with BTX biodegraded fungi which was screening by incubator shaker experiment. The factors which influent purifying performances of biofilter were investigated, including of BTX loading, BTX concentration, empty bed retention time (EBRT), character of microorganism medium, and environmental temperature. The reactor pressure drop is also analysised.The results of experiments show that removal loading of biofilter was increased along with the loading of BTX, the higher of entry loading the removal loading line are farer of 100% removal line. The lower EBRT is, the worse the reactors' performance is. The biofilter degradation efficiency has good results in low and medium concentration of BTX. The biofilter packed with AC gain the best performance and the highest pressure drop, the CP has good performance in biofilm attachment, purifying efficiency, pressure drop, and the AC/CP include of good performance of AC's high purifying efficiency and CP's low pressure drop, so it can be used in industrial scale. Based on the measurement results and used the Ergun equation we analysised the pressure drop of CP biofilter. The air voids and sphericity were obtained. We also study the influence of temperature for the purifying efficiency, the result indicated that if the temperature is lower than 10℃ the purifying efficiency decrease quickly, so the biofilter should be heated as to hold the purifying efficiency.In the second stage we made two new type reactors which can control the temperature of the reaction. The effect of temperature and microorganism mediumhumidity has been investigated. The results indicated that the purifying efficiency in high temperature(30°C—40°C)is higher than low temperature and the fungi have good ability to grow in dry condition. High humidity is disadvantage to the purifying efficiency. In the end the conclusions which we obtained is: for this study the optimistic temperature is 32.7 °C and optimistic range of humidity is 30%~ 50%.