The ZABOCS Bio-Trickling Filter system from Evoqua Water Technologies can be designed to treat up to 15,000 cfm of odorous air per tower and to handle high H2S concentrations of greater than 500 ppm with better than 9 percent removal. It uses random-packed polyurethane foam cubes as the support for biomass growth. The media bed is continuously irrigated by circulating the sump liquid and nutrients over the media. Makeup water is added to maintain the pH of recirculating liquid, providing an optimum environment for the preferential growth of sulfur-oxidizing bacteria. The towers are fabricated from vinylester FRP, and each unit is equipped with a custom biofilter process controller and optional variable-speed drive for the fan. The optional two-stage system provides a neutral pH stage to promote better oxidation of VOCs and organic odors. 866/926-8420; www.evoqua.com.