Biotreatment of Odors from the Zimpro Sludge Conditioning Process
Management of odor emissions generated during thermal sludge conditioning is a well known disadvantage of the “Zimpro” process. Traditional methods of using chemical oxidation and high temperature destruction result in the formation of secondary products, such as chlorine gas, organic halocarbons or nitrogen oxides. In this study, biotrickling filter technology was evaluated at the Villa Hills wastewater treatment plant, operated by Sanitation District No. 1 in Northern Kentucky. The objective of this pilot-scale study was to assess the performance of PRD Tech’s biotrickling filter for treating the headspace air of the sludge tanks, which hold heat treated sludge before filtration and landfill disposal. Air samples were taken from the inlet and outlet of the biotrickling filter, and analyzed using an odor panel, odor meter (Sensidyne Inc., Clearwater, FL), and measurement of detection and recognition thresholds by an independent laboratory (St. Croix Sensory, Inc., Stillwater, MN). Experimental results demonstrated that PRD Tech’s biotrickling filter was able to significantly reduce Zimpro process odors from the sludge holding tanks, achieving greater than 99.9% reduction in the detection and recognition thresholds. Further, the biotrickling filter’s performance was manipulated by varying the inlet concentration of ammonium chloride in the nutrient mixture. Sensidyne’s odor monitor readings were correlated with the odor panel’s response and the detection and recognition threshold values. Preliminary economic analysis has shown that biotrickling filter is a cost-effective technology for odor abatement at wastewater treatment plants.