活性污泥中臭氧传质效率的理论分析与实验研究

Theoretical Analysis and Experimental Research of Ozone Gas Mass Transfer Efficiency in Activated Sludge

在理论分析的基础上,首先建立了臭氧传质效率与系统参数间的数学模型,给出了臭氧传质效率U的影响因素,即污泥浓度、进气浓度、混合液的高度h、表观气速uobs和气泡直径d.通过试验设计,进而考察了这些影响因素对臭氧传质效率的贡献.结果表明,混合液的高度h和气泡直径d对臭氧传质效率的影响最为显著,而污泥浓度和进气浓度、表观气速uobs的影响很小.当混合液高度h为0.2 m时,臭氧的利用率仅为0.45;h为0.8 m时臭氧的利用率为0.883;h为1.4 m时臭氧的利用率几乎为1,臭氧的利用率和高度呈现较好的指数关系.在h为0.8 m的混合液中,d由0.007 5 m减小到0.005 m时,U值从0.89增大到0.96;h为0.6 m的混合液中也出现类似情况,d由0.007 5 m减小到0.005 m时,U值从0.80增大到0.93.最后得到臭氧传质效率U、混合液高度h和平均气泡直径d间的定量关系表达式,其相关系数R2为0.861 6,可为工程设计提供一定的参考依据.

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 uobs 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 uobs 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 R^2 equal to 0.861 6, was finally obtained, as a reference tool for project design.