WASTEWATER TREATMENT FACILITY ODOR CONTROL USING ACTIVATED SLUDGE SCRUBBING AND INCINERATION

The Fitchburg, Massachusetts East Wastewater Treatment Facility uses two-stage nitrification to treat wastewater that is primarily municipal in origin along with a significant quantity of trucked septage and biosolids. Prior to initiation of the improvements described in this paper, the City had taken extensive steps to reduce odor generated by the facility. Major odor reduction initiatives included a five million dollar upgrade to the incinerator exhaust air handling system, addition of ferrous chloride to the influent of the primary clarifiers for H2S control and installation of covers on the primary clarifier effluent channel.Even before the improvements to the incinerator exhaust controls were complete, the City recognized that further control measures would be required to address other odor sources at the facility. The City retained the team of Dufresne-Henry, Inc. and Bowker and Associates to develop a systematic approach to providing the additional odor control required.The initial planning effort, conducted in 1996, consisted of the following major tasks.Quantify and characterize odorous emissions from major odor sources throughout the facility. The results of this task were used to determine which processes at the facility warrant odor management.Identify enclosure types for odor sources that are currently open to the atmosphere.Evaluate alternative methods of odor treatment to identify the technology or combinations of technologies that best meet the needs of the Fitchburg East WWTF.Develop a comprehensive odor control plan including the projected capital cost and implementation schedule.The study recommended that odor control be provided for the primary clarifiers, gravity thickeners, sludge holding tanks, dewatering room and influent screenings room using a combination of activated sludge scrubbing and incineration. Following completion of the study, the project team immediately began work to procure funding for the recommended improvements and initiate final design. This paper provides a description of the planning and final design efforts and discusses the performance of the system during its first 20 months of operation.