Economic Aspects of Sludge Dewatering and Disposal

The economics of sludge handling for large plants utilizing vacuum filtration and incineration or land disposal have been investigated using the total disposal system concept. Disposal system costs were found to be most sensitive to vacuum filter cake moisture content. For this reason vacuum filtration studies were made with cake moisture being a major parameter as well as yield. Filter leaf tests and in-plant studies were made utilizing four different types of sludges: raw primary, digested primary, activated, and a blend of the three previous types. It was found that sludge type, septicity, feed sludge solids content, and vacuum filter form time were the major parameters controlling the economics of vacuum filtration. Total disposal system economics were evaluated using vacuum filtration coupled with incineration and vacuum filtration followed by truck hauling and land disposal.