Factors Impacting Volatile Organic Compound Removal In Biotrickling Filter

Biotrickling filtration is an established technology for volatile organic compounds (VOCs) removal from waste gas streams. This technology utilizes microbe to capture VOCs which attached with media, and it has advantage in some aspects such as low cost, handy operation and no recontamination, and its predominance is obvious when it is used to treat VOCs that have low concentration and are degraded easily by microbe especially. Thus, Biotrickling filtration has becomed the hotspot recently. Growth and accumulation of biofilms in media of biotrickling filters play an important role for VOC removal. The accumulation of excess biofilms can influence VOC removal.In this paper, simply and practical dynamic mathematical models were developed to simulate the growth and accumulation of biofilms and the spatial and dynamic variations of the thickness of biofilms within the media based on gas-liquid double film theory, which is a differential equation system consist of dynamic equations of VOC concentration in gas phase and biofilm phase and dynamic equations of the thickness of biofilm. Simultaneously, the parameters of these models were estimated and numerical implementation was eastablished. Toluene was selected as the model VOC. Sensitivities of the incoming toluene concentration and gas empty bed contact time (EBCT) to VOC removal efficiencies of biofilters and toluene removal efficiencies to these parameters were also investigated.Results about this reserch were showed as below. Thickness of biofilms increased with increased time at a certain location within the trickle-bed and profiles of the thickness and the growth rate of biofilms along the medium depth in the reactor dropped gradually at a certain time. The growth rate of biofilms also increased with increased incoming toluene concentration and gas EBCT at a constant toluene loading rate. VOC removal efficiency ascended at first and declined afterwards in the course of operation. VOC removal efficiency increased due to the fall of incoming toluene concentration or the increase of gas EBCT. If incoming toluene concentration gas EBCT increased, the time of the peak value of VOC removal efficiency lagged accordingly. These results accorded with the fact compared with experimental results and research results which were published.Growth and accumulation of biofilms in media of biotrickling filters can be calculated in the conditions of changing many parameters by these models. Thus, in practice, we could adjust the parameters in order to control the growth and accumulation of biofilms, which can help enhause VOC removal efficiency and nake biotrickling filters run efficiently and normally.