Performance of integral polypropylene packing coated with polydimethylsiloxane in biotrickling filter for toluene elimination

Biotrickling filters (BTFs) for volatile organic compounds (VOCs) have attracted tremendous research attention in the field of environmental engineering. However, the problem of clogging occurred during the long-term operation limits their practical applications. To alleviate the clogging, an integral polypropylene (PP) packing coated with polydimethylsiloxane (PDMS) was prepared, and in combination with fungus, its performance was investigated for toluene elimination. Two laboratory-scale BTFs were started at low toluene concentrations of 200–900 mg·m−3. Subsequently, a series of experiments were conducted at toluene concentrations of 47–2906 mg·m−3, with empty bed residence time (EBRT) values of 50 and 40 s. Toluene removal efficiency reached 100 % at the inlet toluene concentration of 296–560 mg∙m−3 for EBRT of 50 s. The maximum elimination capacity (EC) of 98 g∙m−3∙h−1 was obtained at an inlet toluene load of 117.67 g∙m−3∙h−1. Clogging was relieved by manual cleanup, and the BTFs were operated steadily for nearly 8 months. CO2 production was monitored during the whole operation, and toluene mineralization was evaluated simultaneously. Furthermore, the biofilm structure and microbial diversity were analyzed.