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Public Works Engineering: Wastewater Treatment, Grapevine, TX
Brown & Gay Engineers, Inc. was selected to perform a master plan for odor control at the City of Grapevine's 6 mgd WWTP. As the City continues to expand, with $500,000+ homes surrounding the plant, the City staff wanted to identify improvement options throughout the plant to reduce odors. Brown & Gay Engineers identified the treatment units with odor problems and quantified the magnitude of the odor emissions. Evaluation of the plant's process treatments to determine any overloading or inefficiencies that may be creating or could later create odor problems was performed. Our engineers then evaluated specific odor control measures that could be taken to contain and treat any odorous emissions from any of the specific treatment units. Rather than taking air quality samples around the plant and performing air dispersion modeling, the City preferred to take advantage of the experience of the consultants and of the City's staff in identifying problem areas and developing solutions.
Initial investigations indicated that more than 75 percent of the odor reduction can be accomplished for less than 25 percent of the total cost required to eliminate 99 percent of the odors. Process improvements which were identified included replacing course bubble diffusers in one set of aeration basins with fine bubble to free up more air for appropriate aerobic digestion (and the energy savings pays for the improvements in less than 3 years) and eliminating the aerobic digesters completely (a major odor source when an upset occurs) and landfilling dewatered but undigested sludge.
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