Preparing coal slurry from organic wastewater to achieve resource utilization: Slurrying performance and dispersant suitability

Organic wastewater has a complex composition and contains various pollutants. Coal-water slurry is a cost-effective new technology to treat organic wastewater and recycle the organic matter in wastewater. In this paper, we prepared a slurry with various dispersants for ammonium-forming wastewater, desulfurization wastewater, pharmaceutical manufacturing wastewater, and deionized water. We studied the slurrying performance of organic wastewater and the suitability of dispersants in the preparation of the coal-wastewater slurry. We found that the incorporation of the desulfurization wastewater and the pharmaceutical manufacturing wastewater benefits slurrying while incorporating ammonium-forming wastewater will increase the apparent viscosity of the slurry. The prepared coal-wastewater slurries all had good pseudoplasticity, and showed shear-thinning fluid characteristics at higher solid concentrations. The consistency coefficient of the coal-wastewater slurry was larger than that of the coal-water slurry, and the rheological index was smaller. This means that the addition of wastewater can improve the pseudoplasticity of the coal-water slurry, which is beneficial to industrial applications. The coal slurry that was prepared with ammonium-forming wastewater was the most stable. The incorporation of other wastewater types will reduce the stability of the slurry leading to easy agglomeration. The difference in the slurrying effect of the different dispersants is not obvious in the wastewater environment, but the effect of the wastewater is dominant. The slurry that was prepared with ligninesulfonic acid sodium salt was the most stable. Here, the functional groups in its molecular structure easily form hydrogen bonds, preventing the agglomeration of the coal particles.