Kinetic modeling and experimental verification of a swirl flocculation-enhanced reactor: A case study of coal chemical wastewater pretreatment

In this study, a swirl flocculation-enhanced reactor (SFR) was designed to address the problems of high dosage and poor pollutant removal in the pretreatment process of coal chemical wastewater (CCW). The effects of different height-to-diameter (H/D) ratios, stirring speed, and impeller length on SFR flow field were analyzed by computational fluid dynamics (CFD) simulation. The optimal H/D and operating condition of SFR were determined by comparing and analyzing fluid velocity, eddy viscosity, and turbulent kinetic energy. Then the lab-scale SFR was manufactured to conduct agglomeration tests. The results showed that the flocculation effect was the best when the H/D ratio of SFR is 8:5 and the mixing blade length was at 3/10 of the reactor as well as 180 r/min of agitating rate. The removal rates of oil, suspended solids (SS), chemical oxygen demand (COD) and phenol in CCW could reach 73.43%, 87.88%, 78.63% and 65.20%, respectively. In addition, the plausibility of SFR design was further validated by the fact that the reagent dose was reduced by 50-60% and the removal rate was increased by 20-30% in comparison with the beaker flocculation experiment. The SFR flow field flocculation enhancement mechanism was analyzed. It is expected that the reactor designed in this work, has a wide range of industrial applications in the CCW treatment.

Automated summary

This study designed a swirl flocculation-enhanced reactor (SFR) to address the issues of high dosage and poor pollutant removal in the pretreatment process of coal chemical wastewater (CCW). Through experimentation and computational fluid dynamics (CFD) simulation, the optimal parameters and operating conditions of the SFR were determined, and its feasibility and effectiveness in CCW treatment were validated.