Trickling Filters Foul Air Treatment with Chemical Scrubbers and Removal Efficiencies for Methyl Mercapatan and Dimethyl Sulfide

In 2014, I published an article discussing the trickling filters (TF) foul air characteristics and different activated carbon media and their efficiencies to treat the TF process foul airs at the Orange County Sanitation District (OCSD) wastewater treatment plant in Huntington Beach, California. It was also presented at the WEF Odors and Air Pollutant Conference in 2014. The article stated that activated carbon media was not able to remove dimethyl sulfide, dimethyl disulfide, and carbon disulfide (or some Volatile sulfur compound (VSCs) or reduced sulfur compounds - RSCs) from the highly saturated foul airs that are generated from the secondary treatment process. Furthermore, frequent carbon media replacement has become an economic burden for OCSD. Therefore, OCSD has installed an intermediate treatment system (chemical scrubbers) prior to the carbon scrubbers to treat the foul airs. The new odor control system is arranged such that the foul air can be discharged with or without the carbon media treatment. The chemical scrubber technology is selected based on the space availability, costs to operate and maintain the odor control system, OCSD’s past experience with chemical scrubbers, and treatment efficiency for the foul air inlet concentrations at the secondary TF process. In general, chemical scrubbers are primarily designed to treat hydrogen sulfide, however, the project team considered possibilities of chemical scrubbers treating other odors that might have impacted the neighbors.This paper will provide odor analysis results from the chemical scrubbers and their treatment efficiencies. The data will consistently show that chemicals scrubbers, with pH and ORP at the OCSD normal operating control levels, can effectively remove hydrogen sulfide (H2S), methyl mercaptan (MM), and dimethyl sulfides (DMS), but are inefficient in removing carbonyl sulfide (COS) and carbon disulfide (CDS).