Pilot study on advanced treatment of geosmin and 2-MIB with O3/GAC

Abstract

Abstract The removal efficiencies of geosmin/2-MIB by conventional treatment (flocculation, sedimentation and sand filtration) combined with advanced treatment (ozonation and granular activated carbon (GAC) filtration) in a pilot-scale experiment were investigated in a comprehensive manner. The objective of this study is to provide useful information for practical applications to solve the taste and odor problem during algal blooms in Lake Taihu. Results showed that the conventional treatment removed 38–59% and 36–64% of 2-MIB and geosmin, respectively, with ozone dosage from 0 to 1.0 mg/L. In particular, the increase in ozone concentration promoted the removal of 2-MIB/geosmin by sand filtration, meanwhile lowering the odorant removal efficiency by GAC filtration, with the key reason being the higher biomass produced in the sand filter through the strengthening effect of the ozonation. The organics with higher molecular weight (MW) showed the most significant decline in the pre-ozonation process with 1.0 mg/L ozone dosage, resulting in an enhanced removal efficiency of 2-MIB/geosmin by pre-ozonation. With ozone dosage of 1.0 mg/L, geosmin and 2-MIB in the treated water were 0.1 and 3.85 ng/L, respectively, which were below their odor threshold concentrations (OTCs) with the preliminary concentration of ∼200 ng/L of 2-MIB/geosmin.