BIOSOLIDS ODOR CONTROL IN MONROE COUNTY, NY

During the month of June 2002 an odor control study was completed on the biosolids being trucked to the landfill from the Monroe County's NW Quadrant WWTF. Prior to the study the County had been using sodium hypochlorite for odor control in the biosolids. A study was proposed to treat approximately 80 cubic meters per day of biosolids with varying concentrations of a proprietary solution of nitrate salts. Three major objectives were defined for this study: First to judge overall odor control in biosolids as a whole using the proprietary solution of nitrate salts. Secondly the study was to judge the effectiveness of treating the biosolids during transport only. The third objective was to try and control odors during all phases of the biosolids thickening process.Completing the three objectives was accomplished with two stages. The first treatment stage involved spraying the biosolids as they came out of the centrifuge with a proprietary solution of nitrate salts for treatment only in the transport trucks. Evaluating the odors of the biosolids as they were offloaded at the landfill helped define the conclusions for the first and second objectives, which were overall odor control effectiveness and transport only odor control. These two objectives utilized prevention of odor methodology. A second treatment stage helped define the results of the third objective of controlling odors throughout the biosolids thickening process.Accomplishing this objective was achieved by applying the nitrate salts to the sludge holding tank prior to the centrifuge for both odor control in the biosolids truck loading facility and in the trucks to the landfill. To control odors in the biosolids handling building a patented process of removal for existing sulfides and other odors was utilized.The conclusions of the study are summed up as follows:Monroe County was able to daily replace about 4400 liters of sodium hypochlorite (bleach) with about 120 liters of a proprietary solution of nitrate salts and be effective.The “odor” from nitrate salts treated biosolids is different (not chlorine smelling), but acceptable from both the operators viewpoint and personnel at the landfill.Dosing the sludge holding tank was more effective in controlling odors in the biosolids truck loading facility than spraying the cake alone.Due to the success of the study the County has switched their odor control for biosolids from the sodium hypochlorite prevention methodology to a removal and prevention nitrate salt addition methodology. This use of the proprietary solution of nitrate salts technology in biosolids may be used for greater and/or more economical odor control in other facilities.