UV-TiO2 Treatment of Odorants and Odors Associated with Poultry Operations.

Advanced oxidation technologies such as various combinations of UV/TiO₂/O₃ have the potential to decompose multiple odorous volatile organic compounds (VOCs). The present study used a dynamic (flow-through) setup to explore the effectiveness of UV-TiO₂ photocatalysis for treating the odors associated with poultry operations. A photoreactor was constructed out of a 2.5-liters quartz tube equipped with a TiO₂–coated support and surrounded by a ring of 24 individually controlled 18W "black light" lamps (365 nm). The odor source was obtained by purging fresh or aged suspension of poultry manure. Air samples were withdrawn through ports before and after the photoreactor to assess the effectiveness of the various treatments. Sampling was achieved either by means of headspace solid phase microextraction for GC-MS analysis of specific VOCs, Tedlar bags for odor analysis by dynamic olfactometry, or by Kitagawa color tubes for ammonia measurements. Experiments were designed to examine the effect of flow rates (i.e. residence time), number of lamps in use (i.e. energy dose), and the role of TiO₂. Removals of key manure-associated odorants, such as dimethyl disulfide, dimethyl trisulfide and p-cresol, were between 80 to ~100% (decreased to below detection limit). The total odor was reduced from the initial 70,000 odor units/m³ by 75% in one experiment with fresh manure suspension. There was no significant reduction in odor involving aged manure where initial odor concentration was 700 odor units/m³. The latter was presumably due to the contribution of odor from trace levels of ozone, which was generated under the photocatalytic conditions. Percent of reduction for ammonia ranged between 0-50% in the various treatments. The reported removals were obtained for residence (treatment) times ranging from only a few and up to a maximum of about 10 seconds. After optimization, this approach may become applicable for the treatment of outflow air at mechanically-ventilated barns.