Odor Control at a Large Biosolids Dewatering Facility

Control of odors from biosolids processing facilities, including storage wet wells, centrifuge dewatering, open conveying, biosolids storage silos and truck loading, can be a difficult and daunting task due to the various types of odor that must be controlled and the large size of the containment structures that must be ventilated. The Los Angeles County Sanitation Districts operates one of the largest biosolids dewatering and handling facilities in the United States at its Joint Water Pollution Control Plant in Carson, California. The Joint Water Pollution Control Plant handles over 350 dry tons per day of biosolids. Due to the plants close proximity to residential neighborhoods, large retail outlets and several major thoroughfares there are both regulatory and public pressure to have non-detection of off-site odors from the biosolids dewatering and processing facility. To better determine the odor sources from the biosolids dewatering and processing facility and a means to control the odors, a thorough study was conducted. The study used both odor panel analyses and individual compound concentrations to determine major odor sources. The odor panel results were used in an atmospheric dispersion model to estimate off-site odors. The atmospheric dispersion model determined several odor sources that could possibly generate off-site odors. To control odors and reduce off-site odor impacts, several potential major odor sources will be covered, ventilated and sent to an odor control device. A large biofilter will be used to treat approximately 175,000 cfm of the ventilated odorous air.