Odor Control using Novel Biofiltration Media with a Hydroxyl Generator Polisher

A novel biofiltration media capably of removing greater than 99% removal of hydrogen sulfide at contact times less than 10s was evaluated with the addition of a hydroxyl generator designed to polish odor causing constituents not removed by the biofilter. Biofiltration of hydrogen sulfide is accomplished primarily by autotrophic acidophilic microorganisms whose primary metabolic role is the conversion of hydrogen sulfide to sulfuric acid. Since hydrogen sulfide makes up the majority of odor causing compounds, the removal of inorganic hydrogen sulfide is effective at odor control but organic odorous compounds can remain. Oxidation of organic compounds is an effective and proven method for destroying organic compounds and if hydrogen sulfide is removed, the concentration of oxidant demanding compounds is greatly reduced. The combination of novel biofiltration media with a hydroxyl generator was evaluated at two different sites. A preliminary investigation was completed at the Northwest Valley Water Reclamation Plant in Sun City, Arizona by treating a portion of the biofilter effluent with a hydroxyl generator. The biofilter removed >99.5% of the hydrogen sulfide at loadings up to 102 gH2S m–3 h–1 which corresponded to greater than 90% reduction in odor units. The polisher further reduced the remaining odor units by >99% and the total system reduction in odor units was greater than 99.95%. A prototype hydroxyl generator capable of treating the entire air flow from a biofilter was evaluated at the Boston Road Lift Station located in Gilbert, Arizona. The hydroxyl generator was capable of removing approximately 80% of the odor intensity emitted from the biofilter and the combination of the biofilter and the hydroxyl generator removed over 99% of the H2S. The hydroxyl generator was effective at polishing residual odors caused by both organic and inorganic compounds.