A Comprehensive Approach to Odor Control at the Manchester NH Water Pollution Control Facility

The City of Manchester, New Hampshire operates a 34-mgd secondary water pollution control facility that had been plagued by frequent odor complaints. The City undertook a phased program to capture and treat all wastewater odors from the inlet through the aeration basins as well as the solids handling facilities. Wastewater is now contained under covers until it reaches the secondary clarifier influent channels. The work was accomplished in four phases, constructed over a nine-year period. Successive phases of work were developed on the basis of dispersion modeling impacts.Odor complaints are now quite infrequent and the facility is regarded as a good neighbor in the community.A number of different techniques and technologies were employed to isolate, capture and treat facility odors. Some applications are unique to this facility. Significant features include:A stand-alone and automated 50,000 gal/day septage receiving facility that allows septage to be off-loaded, screened and metered into the wastewater at low rates. Electronic scanners allow haulers to discharge their loads and be billed without WPCF operator intervention;Isolation of foul air streams within the influent pumping station and treatment of the concentrated odors with a 10,000 cfm activated carbon system;A mist chamber system to treat odors from sludge thickening, dewatering and scum thickening;Treatment of sludge storage and conveyance odors in fluidized bed incinerators.Covered grit chambers, influent channels and primary clarifiers;Fiberglass covers for mechanically aerated aeration basins and treatment by biofiltration;A 44,000 cfm biofiltration system to treat tankage and channel head space. The system uses incinerator waste heat to temper the inlet air whenever ambient temperatures are lower than 50 degrees (deg) F;This paper presents the background, design intent, design features, and effectiveness of each of the capture and control technologies employed.