APPLICATION OF A DYNAMIC BIOFILTRATION MODEL TO A TWO-STAGE BIOFILTER THAT TREATS HYDROGEN SULFIDE AND ORGANIC SULFUR COMPOUNDS

A dynamic biofiltration model for odor control was calibrated and validated using hydrogen sulfide (H2S) and methyl mercaptan (MeSH) data obtained from a two-stage biofilter that was packed with 15% compost and 85% wood chips. The model is incorporated into a user-friendly software called Biofilter™. Biofilter™ comes with a detailed user's manual and can be used to support design and optimization of biofilters and biotrickling filters used for treatment of odorous air emissions and VOCs. Although the model has been evaluated with H2S data obtained from lava rock biofilters previously, this is the first time that a model of this complexity was evaluated with odor-causing organic sulfur compound data obtained from a biofilter packed with an organic medium. The effects of the gas residence time and pH on MeSH removal efficiency are discussed based on model simulations. It was found that increasing the gas residence time was important for increasing the MeSH removal efficiency and control of pH was critical for improving the performance of biofiltration of MeSH. For example, at pH 2.6, the simulated removal efficiency of MeSH was 76% with a residence time of up to 50 seconds; but at pH 6.4, the simulated removal of MeSH was 97% with a residence time of only 20 seconds. These modeling results suggest that control of pH is critical if one wishes to improve the performance of MeSH removal during biofiltration. In addition, the performance of a biofilter packed with a mixture of wood chips and compost and a biofilter packed with lava rock were compared for H2S removal efficiency and modeling results showed that biofilter packed with lava rock was more efficient than the biofilter packed with wood chips and compost.