Field Measurements and Modeling of Two-Stage Biofilter that Treats Odorous Sulfur Air Emissions

Because the presence of hydrogen sulfide $\left(H_{2}S\right)$ and methyl mercaptan (MeSH) inhibits the removal of some organic reduced sulfur compounds (e.g., dimethyl sulfide, ${\mathrm{Me}}_{2}S)$ in biofilters, a two-stage biofilter may be an appropriate method to treat a mixture of reduced sulfur compounds. This work studied the treatment of odorous air emissions [a mixture of $H_{2}S\text{,}$ MeSH, ${\mathrm{Me}}_{2}S\text{,}$ and dimethyl disulfide $\left({\mathrm{Me}}_2{S}_2\right)]$ using a two-stage biofilter. $H_{2}S$ had the highest overall removal efficiency (96%) followed by MeSH and ${\mathrm{Me}}_{2}S$ (90 and 91% removal, respectively) and ${\mathrm{Me}}_2{S}_2$ (81%). Most of the removal of $H_{2}S\text{,}$ MeSH, and ${\mathrm{Me}}_2{S}_2$ occurred in the primary biofilter (72% $H_{2}S\text{,}$ 66% MeSH, and 52% ${\mathrm{Me}}_2{S}_2)\text{,}$ while most of the ${\mathrm{Me}}_{2}S$ removal occurred in the secondary biofilter (64% ${\mathrm{Me}}_{2}S)\text{.}$ A dynamic model that describes biofiltration was calibrated and validated to $H_{2}S$ and MeSH field data. This is the first time a model was evaluated with organic odor-causing sulfur compound data obtained from a biofilter packed with compost and wood chips. Model simulations showed that $H_{2}S$ removal in a lava rock packed biofilter would be better than in a similar biofilter packed with compost and wood chips.