The Slurrying Properties of Coal Water Slurries Containing Raw Sewage Sludge

Municipal sewage sludge always includes considerable amount of water, noxious substances, and varying chemical compositions; therefore, sludge utilization is imposed. Coal-sludge slurry (CSS), which is made by blending sewage sludge with coal, water, and additives, is being identified as a new and effective sludge utilization technology. The main objectives of the present investigation are research on the slurrying, rheology, and stability properties of five CSSs, and determine the influence of sludge type, sludge mixing proportion (alpha), temperature, and shear rate on the slurrying properties that play a critical role in CSS technology. Results showed that (i) the maximum solids loading (MSL) dropped sharply with the rise of alpha, ranging from 55.22% to 59.41% in the alpha = 15% case, compared to 69.16% in the alpha = 0 case; and (ii) the apparent viscosity dropped as the temperature rose from 20 degrees C to 50 degrees C, in an approximate linear correlation. All CSSs exhibited a pseudo-plastic rheology, and increasing omega and alpha resulted in a trend more toward pseudo-plastic behavior; moreover, the poorer the slurryability of the sludge, the more apparent the pseudo-plastic trend. The static stability was getting better for CSS, compared to coal water slurry (CWS).