The Slurrying Properties of Coal Water Slurries Containing Raw Sewage Sludge

Abstract

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 (R), 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 R, ranging from 55.22% to 59.41% in the R = 15% case, compared to 69.16% in the R = 0 case; and (ii) the apparent viscosity dropped as the temperature rose from 20 °C to 50 °C, in an approximate linear correlation. All CSSs exhibited a pseudo-plastic rheology, and increasing ω and R resulted in a trend more toward pseudo-plastic behavior; moreover, the poorer the slurryability of the sludge, the more apparent the pseudoplastic trend. The static stability was getting better for CSS, compared to coal water slurry (CWS).

The utilization of sewage sludge by blending with coal water slurry

“…However, rich interstices and fluffy structures endow sludge with a strong water-bonding ability. The viscosity of slurry exhibits an increase after sludge is added [28,29].…”

Slurryability and combustion characteristics of coal‐coking wastewater‐slurry

“…The power law model was used for the evaluation of the rheological properties of the CWS, and it was expressed in the following formula: where τ refers to the shear stress, Pa; K refers to the consistency coefficient, Pa · s; γ refers to the shear rate, s −1 ; and n refers to the rheological index, which determines the flow patterns of CWS: n > 1, dilatant fluid; n < 1, pseudoplastic fluid; and n = 1, Newtonian fluid.…”

Rheological behavior of the sludge in a long-running anaerobic digestor: Essential factors to optimize the operation

“…According to a reported investigation [31], a positive correlation was found to occur between the thixotropy and stability of sludge, which indicated that the sludge with a higher thixotropic index was very stable in storage; while, a stable structure of sludge implied more energy consumption might be required when needed a mixing or transporting operation. In this regard, the thixotropic properties of sludge should be considered in designing a digestion system, especially in the mixing and pumping unit.…”