Influence of waste brake oil on the rheological properties of coal-sludge water slurry.

In this work, the effect of waste brake oil (WBO) on the dispersion property of coal-sludge oil slurry (CSOS) was investigated and comprehensively analyzed. Apparent viscosity of CSOS decreases from 997 to 276 mPa.s with the increasing of SS content from 0 to 12% under the calorific value (CV) of 17.70 MJ/kg and oil/sludge ratio (O/S) of 2.0. The combination of sewage sludge (SS) and WBO could decrease the apparent viscosity of CSOS, and SS content and O/S are two important parameters to affect the apparent viscosity. WBO mainly contains the hydrocarbon compound and a lot of oxygenated functional groups according to its GC/MS results. WBO could cover on the surface of SS and coal particle, and reduce their hydrophobic character and the adsorbance amount of dispersant based on the FTIR, XPS and adsorption performance results. In addition, the mechanism of WBO on slurry characteristics of CSOS was investigated. With the low content of WBO, the liquid bridges from WBO force the solid particles to adhere together and form a stable network structure, thus reducing the flow ability of the suspension. With the increasing of WBO, the network structures could be broken into cells, resulting in a dramatic decrease in viscosity. This research provides a potential way to dispose the SS and waste industry oil.

Oxidation of Congo red by Fenton coupled with micro and nanobubbles.

Dye wastewater is a kind of refractory organic wastewater. Fenton coupled with micro-nano bubbles (MNBs+FT) was used for the degradation of Congo red (CR), aiming at simplifying the organic pollutants degradation process and reducing the cost of the process. The optimum condition of Fenton alone, the outlet pressure of the cavitation process and different combinations on the degradation of CR dye wastewater were discussed in this study. The results showed that the degradation of CR (100 mg/L) could reach 94.4% by using the MNBs+FT at the pH of 7, which was 72% higher than that using Fenton oxidation alone and 79% higher than that using MNBs alone. Based on the same degradation efficiency, the traditional Fenton process alone required 8 times the dose of oxidants of these combination systems, and the synergy coefficient of MNBs+FT was up to 2.44. ESR analysis indicated that ·OH was the predominant active species during the degradation of CR and MNBs+FT improved the utilization efficiency of H2O2 and produced more ·OH. Besides, the MNBs+FT could extend the pH range of the high-efficiency oxidation reaction, and it could also keep a high degradation rate under neutral conditions, which eliminated the process of adjusting the pH and reduced the anti-corrosion requirements of the equipment. According to the economic analysis results, the total cost of treatment for the MNBs/FT was about 13% of the cost of only the Fenton process. This study provides a reference for the application of MNBs+FT systems in full-scale dye wastewater treatment.