| A vapor-phase biological filtration model was formulated, and a systematic protocol was developed for treating industrial emissions containing several chlorinated volatile organic compounds (VOCs), including trichloroethylene (TCE), perchloroethylene (PCE), and dichloromethane (DCM). The model incorporated important phenomena associated with gas-liquid transfer, adsorption, and biofilm degradation. The protocol included the development of experimental techniques for evaluating model parameters, and involved an upscaling design technique using the concepts of dimensional analysis and similitude. Laboratory-scale equilibrium and rate studies were conducted to determine the equilibrium and mass transfer parameters, respectively. Biokinetic experiments were performed to determine the biodegradation parameters. Adsorption and biodegradation parameters were subsequently used as model inputs for predicting the dynamics of biofilter columns. Laboratory-scale biofilter studies for model verification indicated good predictive capability for the proposed model.;Industrial waste streams contaminated by mixtures of chlorinated compounds with high and fluctuating concentrations often render biotreatment inadequate because of their high microbial toxicity. To mitigate this problem, an integrated system combining ultraviolet oxidation and biotrickling filtration (UV-BTF) was investigated. This system, which has the merits of producing photo-oxidation by-products that are more amenable to biodegradation, simultaneously treated air streams contaminated with TCE and PCE. The experimental results demonstrated that the UV-BTF system consistently achieved removal efficiencies exceeding 99% over a wide range of influent TCE and PCE concentrations, as well as mineralization of the oxidation by-products in the biotrickling filter.;Pilot-scale biofilter studies were conducted to examine the potential effects of substrate interactions in VOC mixtures, including (i) DCM/methanol, and (ii) TCE/toluene/acetone. For DCM/methanol mixture, no significant substrate interaction in the biodegradation of DCM occurred. Furthermore, the biofilter packed with GAC and inoculated with a mixed microbial culture performed significantly better than those either packed with anthracite or inoculated with a pure bacterial strain. For TCE/toluene/acetone mixture, acetone and toluene were effectively removed, and TCE degradation was enhanced via acetone/toluene-induced cometabolism. |
