Full Scale Testing of Biofilters for Odor Control at the Los Angeles County Sanitation Districts' Joint Water Pollution Control Plant Biosolids Handling Facilities

Odor control has always been a primary concern for the Los Angeles County Sanitation Districts (Districts) in the operation of its wastewater treatment facilities. During the dewatering, conveying and storage of biosolids there can be the potential to produce significant off-site odors. The Districts' operate one of the largest biosolids dewatering facilities in the United States at its Joint Water Pollution Control Plant, producing over 1700 wet tons/day of biosolids. Odor control at this biosolids dewatering facility is a significant undertaking due to the production of compounds that have low odor detection thresholds and because many of the processing facilities are large and uncovered, which makes enclosing, ventilating and treating difficult. An odor study was conducted, to address the potential odor problem from this facility. The study analyzed the different odor sources and used the odor information in an atmospheric dispersion model. The study indicated that there was a possibility of producing off-site odors, thus odor controls would be necessary. Various odor control technologies were compared and biofiltration was selected as the method to treat odors from the biosolids dewatering facility. Full scale modular biofilters that could treat over 20,000 cfm of air were installed to control odors from the most odorous portion of the facility. Testing was conducted for a year to ascertain the ability of the units to remove odor and air contaminants, to develop the methods for effectively operating the biofilters and to test different biofilter media. Three different types of media were tested with the most effective media achieving 90 percent removal of biosolids odors. The most efficient odor removing media, determined during the testing of the modular biofilters, will be used in large biofilter systems that are currently under construction at the Joint Water Pollution Control Plant. The new biofilters will be some of the largest in the United States and will treat 200,000 cfm of air from the biosolids handling facility.