The pre-conditioning of digested municipal sewage sludge with quicklime prior to dewatering was investigated as an alternative to conditioning the dewatered sludge with quicklime. Powdered lime was added to the sludge in a stirred tank reactor before dewatering in a solid-bowl centrifuge. The preconditioning was found to positively influence the dewatering performance of the centrifuge, resulting in significantly lower specific polymer and lime consumption and a reduced total quantity of dewatered cake for disposal. Total costs for operating chemicals and for transport and landfill of the sludge were determined to be approximately 15 % lower for pre-liming than for the post-liming process.
- centrifugal dewatering
- sludge disposal
- © International Association on Water Quality 1993