Thin-layer sludge dewatering

Provisional experimental have shown that 50 % dry matter in mechanically dewatered sludge is possible for selected combinations of conditioning, pressure time and cake thickness in a pressurized sludge dewatering operation. The thickness seems particularly interesting because the dewatering rate under certain circumstances increase inversely proportional to the squared decrease of the thickness, ref. no. 2. Precision experiments will be carried out using new laboratory equipment and measurements of osmotic as well as mechanical pressures on cakes of well characterized and systematically conditioned sludges. This will contribute to at least an empiral understanding of the dewatering with pressure, time and thickness as key parameters. Through mathematical modelling the results will be generalized. A conceptual design of a continuously operating new dewatering equipment will hence be presented and discussed with regard to building and testing a pilot scale machine. These latter activities are not included in this project. Cooperation between Aalborg University, Thomas Koch Energy and I. Krüger, Ltd. will secure that the overall goal of eventual practical utilization will guide the experimental procedures, the modelling and the interpretation of the results. Ref. no. 1. Energieffektiv slamudnyttelse - slutrapport. Energistyrelsen 1998. Ref. no. 2. Tyndlagsafvanding af spildevandsslam, AAU, Teknisk naturvidenskabeligt Fakultet, Lab. for Miljøteknik, Ole Madsen og Nils Nordholm