[Theoretical analysis and experimental research of ozone gas mass transfer efficiency in activated sludge]

Based on theoretical analysis, a mathematic model was primarily set up to describe the relationship between the ozone mass transfer efficiency (U) and the systematic factors, including sludge concentration, input gas concentration, mixed liquor height h, observed gas velocity u(obs) and the bubble diameter d. By different experimental design, furthermore, the contribution of these factors for transfer efficiency was investigated respectively. The results show that the mixed liquor height h and bubble diameter d impacted the mass transfer efficiency of ozone more significantly, as compared to the other factors of sludge concentration, input gas concentration and observed gas velocity u(obs). When mixed liquor height h was 0.2 m, the ozone gas utilization U was only 0.45; when h was 0.8 m, U increased to 0.883; when h was 1.4, U was almost up to 1. The U and h show strong index relationship. For mixed liquor with h 0.8 m, when bubble diameter d decreased from 0.007 5 to 0.005, U increased from 0.89 to 0.96, and, for mixed liquor with h 0.6 m, similar increase from 0.8 to 0.93 was observed. According to the acquired experimental data, a quantitative expression among mass transfer efficiency U, mixed liquor height h and mean bubble diameter d, with R2 equal to 0.861 6, was finally obtained, as a reference tool for project design.