RESUMO
The impacts of suspended solids in secondary effluent on "tailing" phenomenon in disinfection of E. coli with chlorine were investigated using kinetic disinfection curves. Higher SS concentration led to earlier beginning of "tailing" region with lower inactivation level. Comparison between lg-lg regression analyses of disinfection curves demonstrated that the SS concentration correlated with overall inactivation rate, which decreased by 10 times while SS concentration increased from 6 to 85 mg/L. The results of segmental modeling of disinfection curves showed that the SS concentration (at a range of 10-55 mg/L) correlated with the starting time of "tailing" region as well as the log-kill at the starting point of tailing region (R2 > 0.99). The starting time was shortened from 330 min to 55 min, and the log-kill dropped from 5.8 down to 0.8 with SS concentration increasing. Better removal of SS will improve the lg-kill of E. coli at tailing region and the inactivation rate, resulting in lower cost of construction and running. In addition, higher chlorine dosage and lower pH value could slightly enhance the log-kill in the "tailing" region.
