Effects of raw water quality on the adsorptive removal of 2-methylisoborneol by powdered activated carbon under non-equilibrium conditions

Abstract

Natural organic matter contained in natural water inhibits the adsorptive removal of 2-methylisoborneol (2-MIB) by powdered activated carbon (PAC). We investigated the relationship between water-quality indices and the adsorptive removal of 2-MIB by PAC. We collected three different raw water (i.e., two lake water and one river water) samples twice per month for 10 months. We characterized the raw water using total organic carbon concentration, ultraviolet absorption at 254 nm, electrical conductivity, and excitation–emission matrix analysis. The results were compared with 2-MIB removal rates evaluated from PAC adsorption experiments and revealed that there was no universal indicator that could explain the trends of the 2-MIB removal rate during the overall experimental period. The correlation trends between 2-MIB removal rates and water-quality indices differed significantly between the high and low water-temperature periods. Several water-quality indices related to the organic matter associated with biological processes, especially algal activities (i.e., soluble microbial products, chlorophylls, and phycocyanin), exhibited strong correlations with the 2-MIB removal rates (|R| > 0.7) under certain conditions (e.g., high lake-water temperature). Both the parallel factor (PARAFAC) analysis and fluorescence regional integration (FRI) method could evaluate such behaviors after including the regions associated with algal organic matter in the calculation.