New developments of biotrickling filters: Experiments and theories

Major technical challenges confronting biofiltration technology are: effective support media for biotrickling filters, understanding of biofiltration of mixed contaminants, biofiltration of contaminants at very low concentration, and biofilm model calculation for concentration distribution within a biofilm.; In this research work, a composite media was designed and tested in bench scale biotrickling filters. The media were made of a polymeric support media coated with either activated carbon or sand. The resulted media will inherit properties such as high void fraction, high interfacial area, and low bulk density from the original packing, plus enhanced surface suitable for biofilm attachment and growth. The new media were evaluated along with the original media in bench scale biotrickling filters.; A fibrous packing medium was evaluated in the biofiltration of ethanol in biotrickling filters and microbiofilters. The microbiofilter system, operating according to a new experimental protocol, can be used to determine both reaction rate constants and mass transfer coefficient with the help of a concise mathematical model. The identified parameters are then used to calculate concentration profiles inside a biotrickling filter and to predict its biofiltration performance. This fibrous packing medium was later used in a pilot scale biotrickling filter test to treat ethanol emission found in exhaust gases from baking ovens. The same fibrous media as well as the experimental protocol were also used in studying mixed contaminants biofiltration.; Biofiltration of mixed contaminants was studied using target compounds of alcohols, acetone, acetaldehyde in biotrickling filters and microbiofilters using the fibrous medium. In a batch system, the preference of individual contaminant by the biomass can be carefully examined. Meanwhile, their respective biodegradation kinetics can be investigated by employing a mathematical model, which was also developed to portray the biofiltration process of mixed contaminants in microbiofilters.; A unique convective flow biofilter, for the biotreatment of waste gas with low concentration organic contaminants, was invented and tested successfully in laboratory. Current biofilters employ diffusion mechanism for transport of contaminant to the active cells in the biofilm. The biofiltration effectiveness decreases with contaminant concentration at low contaminant concentration. A convective flow biofilter employs a convective biofilm in which the contaminated air flows through the active biofilm, rather than flow over it. The efficiency of convective transport of contaminants is not affected by contaminant concentration, and hence convective biofilters are expected to be much better than diffusive biofilters at low contaminant concentration. The concept of convective biofilm was implemented using a channellized monolith. Experiments were conducted to compare both diffusive and convective biofilters in the biofiltration of toluene for 3 months. Biofiltration performances were evaluated at various flow rate and inlet concentrations. Mathematical models for both diffusive and convective biofilters were developed to simulate experimental results.; Simple and effective methods were proposed to calculate substrate flux into the biomass and to estimate contaminant concentration distribution within an active biofilm. Results estimated using these methods were compared with numerical solution data and therefore these methods were verified in term of error and accuracy.