GENERATION AND CONTROL OF DEWATERED BIOSOLIDS ODORS

摘要

The Charlotte-Mecklenburg Utilities (CMU) provides water and wastewater services for more than 700,000 customers in seven local governments in Mecklenburg County, and maintains regional agreements with Union, Cabarrus, Lancaster and York Counties. The McAlpine Creek Wastewater Management Facility (WWMF) is CMU’s largest wastewater treatment facility, with average flows approaching 50 million gallons per day (mgd) and a permitted design capacity of 64 mgd. Biosolids production at the McAlpine Creek WWMF currently averages 40 dry tons per day. The McAlpine Creek WWMF currently has four fixed-cover anaerobic digesters that are used to stabilize the biosolids, high-solids centrifuges for dewatering and screw conveyors to transport the dewatered cakes to storage silos. CMU’s preferred beneficial reuse option for biosolids is land application. However, due to offensive odors associated with the dewatered biosolids cake, the final product is not currently suitable for land application. This paper presents an overview of two recently completed studies designed to (1) determine relative differences between dewatering devices and their associated impacts on odor generation potential and (2) ability of chemical addition to dewatered biosolids cake to mitigate odors. Dewatering devices evaluated included belt filter press, lowsolids centrifugation and high-solids centrifugation. Chemicals evaluated in bench-scale testing included lime, sodium hypochlorite and ferric chloride.