Effect of Oxidant Addition on Water Quality and Microfiltration Performance during Water Reclamation

Abstract

Objective:This study investigated the effects of ozone, chlorine dioxide, and chlorine pretreatment on water quality and microfiltration characteristics in the water reclamation facility.Methods:Ozone (0.5-2.5 mg/L), chlorine dioxide (1-5 mg/L) and chlorine (1-5 mg/L) were injected as an pre-oxidizing agent, and membrane fouling and surface damage during microfiltration (PVDF) were assessed. Results and Discussion:The hydrophobic substances were decomposed as the dosages of ozone and chlorine injected increased. However, chlorine dioxide could not effectively decompose hydrophobic organic matters in the range of 1-5 mg/L. In the case of pretreatment with chlorine, the microfiltration operation time was longer than in the case of pretreatment with ozone and chlorine dioxide. As the concentration of chlorine injection increased, the membrane filtration time before backwash gradually increased. Regardless of the type and concentration of the oxidizing agent, the membrane damage rate by the oxidizing agent was less than 1% within 28 days, and no surface damage was observed. Conclusions:Chlorine was considered to be the most efficient pre-oxidizer for microfiltration process with a PVDF membrane to reuse biologically treated wastewater in the wastewater treatment plant.