CONTROL OF ODOR AND VOC EMISSIONS FROM ABS PLASTICS FACILITY

LANXESS' manufacturing facility near Cincinnati, Ohio, produces ABS plastics. Wastewater from the acrylonitrile-butadiene-styrene (ABS) manufacturing process is collected and treated in an on-siteone million gallon per day wastewater treatment facility (WWTF) prior to discharge to the Ohio River.LANXESS has received occasional odor complaints from surrounding businesses and residents in the past and chose to take a proactive approach to controlling these odors by contracting an investigation into odor and volatile organic compound (VOC) emissions from the WWTF and implementing the recommended improvements in a phased approach.Testing was conducted at the WWTF in November 2004 and the results identified the sources with thehighest odor and VOC emissions, including the plant headworks, primary treatment and biosolids processing areas. This information was used to develop a phased approach to controlling emissions from the facility.Phase 1 of the project included the collection of air from the sources with the highest odor detection thresholds (primary flocculation tank and sludge pit) and using it as the intake air source for the existing aeration blowers. The air is injected into the aeration tanks through coarse bubble diffusers and treated via activated sludge diffusion. This system was placed on-line in June 2005 and follow-up testing was conducted to verify odor and VOC removal efficiencies. As expected, this Phase I work was effective but further improvements were required.VOC testing showed air emissions from the facility include aromatic compounds such as ethyl benzene and styrene, reduced sulfur compounds such as hydrogen sulfide, carbonyl sulfide and carbon disulfide and other compounds such as acrylonitrile and methyl ethyl ketone. This mixture of compoundspresented a difficult challenge in trying to evaluate treatment alternatives. Thermal oxidation was always an option but the cost of fuel was a natural concern. Biological treatment of the air would have a lower operating cost but there was not enough data available to comfortably recommend a full-scale system without first pilot testing it to verify performance and develop design criteria.Phase II of the project was a 6-month pilot test to determine the odor and VOC removal efficiencies of a biotrickling scrubber (BTS) and a custom-built, organic media biofilter when operated in parallel and in series. Installation of the pilot testing equipment was completed in November 2005 and pilot testing is scheduled to continue through April 2006. The results of this pilot test willdetermine whether emissions from the ABS plastics facility can be reliably treated biologically orif thermal oxidation will be required. Preliminary results of the pilot tests, including VOC andodor removal efficiencies, will be presented in this paper along with media selection and Empty Bed Residence Time (EBRT) design criteria.The information in this paper will document the results of the initial odor study, show the effectiveness of the Phase 1 improvements and present the results of the pilot testing, showing valuableinformation on the performance of two types of biological treatment systems in the treatment of volatile organic compounds.