Session3: Environmental Hydraulics
Title: UNSTEADY SETTLEMENT TEST AND NUMERICAL CALCULATION OF ACTIVATED CARBON PARTICLES IN STATIC WATER
Lv Tianshu, Huang Shehua
Powdered activated carbon (PAC) has strong adsorption capacity because of its large specific surface area and developed pore structure. It is currently used in advanced treatment of industrial sewage. In the sewage treatment technology using activated carbon, the settling velocity of activated carbon in static water is an important parameter. Based on the process and results of the static water settlement test of powdered activated carbon and combining the physical properties of powdered activated carbon, it was found that the powdered activated carbon does not settle in the static water simply as a single particle, but settles in the form of flocs due to effect of flocculation. Activated carbon flocs are accompanied with flocculation and diffusion when settling, and the change of the intensity of flocculation and diffusion results in the change of the equivalent size of flocs with time, thus affecting the settling characteristics of flocs. Therefore, the hypothesis of "flocculation-diffusion" is put forward when activated carbon particles settle, and the fitting formulas of activated carbon flocs equivalent particle size changed with time are given according to experimental data. Based on BBO equation of unsteady particle movement, the settling process of activated carbon particles in static water is numerically simulated. The calculated results are in good agreement with the experimental values.