In 2004, a major west coast city began construction of two new interceptor sewers. The 12 foot diameter intercept lines relieve hydraulic overloading, but also created a number of turbulent areas where nuisance odors adversely affected the local residential community. These odors were primarily H2S at concentration levels of up to 150 ppm, as well as volatile organic contaminants (VOCs).
Evoqua Water Technologies' solution utilizes our patented, Midas® OCM (Odor Control Media) and Westates® RB-series roll-off box carbon adsorbers. The RB-units are delivered to the site location filled with Midas® OCM. Once the media is exhausted, the RB-units are removed from the site and replaced with new adsorbers filled with fresh media. Midas® OCM is a high capacity odor control media specially manufactured for H2S loadings 4-times higher than other available medias. This relates to longer bed life, longer intervals between replacement and improved safety for operators since the H2S is converted to sulfur versus sulfuric acid, as is the case with other odor control medias.
Five systems have been installed in the city's sewer collection system. Each system treats an air flow of 10,000 cfm and contains 15,400 lbs. of Midas® OCM and 4,400 lbs. of coconut shell carbon. Midas® OCM is effectively used for removal of the H2S and some organics; the coconut shell carbon is used as final polishing and to remove and remaining VOCs. Employees of the city report that upon bringing the Midas® OCM system on-line, there was an immediate elimination of sewer odor at the project site.