Energy-saving Dewatering Technology for Sewage Sludge Using Liquefied Dimethyl Ether

Abstract

We applied DME (dimethyl ether)-based dewatering technology, which has been developed for high-moisture coal, to dewatered sewage sludge and successfully decreased the water content of sewage sludge from 78wt% to 30wt%. Moreover, we clarified that five minutes is enough to dewater sewage sludge as contact time. In addition, the dried sewage sludge was deodorized. Since the temperature of sewage water is approximately constant throughout the year, sewage water and air can be used as sources of heat for the evaporation and condensation of DME. Thus, DME-based dewatering technology can be thought of not only as a dewatering technology but also as a technology for recovery of heat from sewage water.