Effect of inorganic salts on inactivation of Escherichia coli and removal of fulvic acid by ozone in a rotating packed bed

Abstract

This study investigated the effect of different inorganic salts on the treatment of simulated secondary effluent (SE) by ozone (O3) in a rotating packed bed (RPB) – (O3-RPB process), with Escherichia coli (E. coli) and UV254 of fulvic acid as the indicators. The inactivation efficiency of E. coli and removal percentage of UV254 were studied under different rotation speeds of the RPB and varying concentrations of inorganic salts such as NaHCO3, Na2SO4 and CaCl2. Results indicate that both the inactivation efficiency of E. coli and removal percentage of UV254 increased with an increasing rotation speed of the RPB but decreased with an increase in concentrations of the inorganic salts. Analyses on the mechanism of the treatment process reveal that the inorganic salts consume O3 and ·OH to generate products with lower oxidation ability, and thus result in a poor treatment effect on the effluent. This work provides fundamentals for the O3-RPB process in the treatment of SE from urban wastewater treatment plants.