Research on the application of slurry fuel prepared by mixing wastewater sludge and coal

摘要

Large volumes of wastewater sludge are generated along with acceleratedindustrialization and urbanization. Coal sludge slurry (CSS) is proposed to disposesludge, wherein sludge is taken as carbon-containing substance and mixed with coalto prepare slurry fuel. In the study, the slurryablity and rheological properties of CSSwere researched, and alkaline pretreatment was tried to improve the slurryability.Pilot-scale combustion test of CSS was also performed. Results showed that, addingsludge decreased the slurryability. The maximum solid concentration (SC_(max)) of coalwater slurry (CWS) was 67.10%, while after adding sludge, SC_(max) of CSS decreasedsharply to 57.39%. Fortunately, alkaline pretreatment of the sludge evidentlyimproved the slurryability. SC_(max) of the CSSs made of modified sludge, which waspretreated by NaOH and Ca(OH)_2 of 0.10 g/g dry sludge for 24 h, respectivelyincreased to 60.17% and 59.07%. CSS had good combustion performances. Thetemperature at main combustion zone reached above 1250 °C, and combustionefficiency reached 99.75%. In general, CSS provided a technically feasible, safe andeconomical method for utilizing sludge.