A COORDINATED APPROACH TO ODOR CONTROL IN COLLIER COUNTY, FLORIDA

The Collier County Wastewater Department serves over 45,000 customers covering an area of 75 square miles in Southwest Florida. The collection system includes more than 675 lift stations with over 700 miles of gravity and force main pipes leading to two Regional Water Reclamation Facilities. The combined treatment capacity of 26 million gallons per day (MGD) will be expanded to 40 MGD by June 2005.Prior to 2000 odor control was dealt with on a case by case basis, with little coordination between the treatment plants and lift stations. Fueled by an ever-increasing population, the large influx of seasonal residents and tourists, and the growing importance of odor control in the wastewater treatment process, a coordinated approach to odor control was called for. In 2000 the Collier County Wastewater Department began a comprehensive study and evaluation to standardize and coordinate their response to odor issues.Advanced, multi-stage wet chemical scrubber systems were selected for the higher volume, more centralized odor control needed at the treatment plants. Eight wet chemical scrubber systems are currently in operation with treatment capacities ranging from 8000 cfm up to 25,000 cfm. Odor control is provided for the headworks, equalization basins, aeration basins, sludge holding tanks and dewatering operations at both the South Regional and North Regional Water Reclamation Facilities.With more than 675 lift stations, and over 700 miles of pipes, the collection system presented a more complicated and potentially more troublesome odor control problem. In 2001 the County retained Camp Dresser and McKee Inc. (CDM) to perform a comprehensive evaluation of the odor and corrosion control requirements for its wastewater collection system. The study included extensive field sampling (liquid and vapor phase), and field evaluation of alternative odor treatment methodologies including engineering design considerations, chemical addition, and a variety of odor treatment systems. Based on this study, Collier County is proceeding with a combination of chemical addition to suppress sulfide production, and biofilters to ventilate and remove the odors at selected lift stations. To date 26 biofilters of various capacities are on-line, treating from 75 cfm to 1000 cfm. By the end of 2004 a total of 35 biofilters will be in operation.This paper will present results from the odor and corrosion control study, actual performance data for the on-line chemical scrubbers and biofilters, chemical usage data for the scrubbers and collection system, and operation and maintenance experience. In addition, this paper will discuss the Collier County Wastewater Department's systematic response to odor complaints and the decision making process involved in balancing the chemical costs, operating costs and capital costs of the odor control strategies.