Comparative analysis of ozonation (O3) and activated carbon catalyzed ozonation (ACCO) for destroying chlorophyll a and reducing dissolved organic carbon from a eutrophic water reservoir

Abstract

Ozonation (O3) and activated carbon catalyzed ozonation (ACCO) processes were compared in terms of reducing chlorophyll a, turbidity, UV254 absorbance, dissolved organic carbon (DOC) and color from eutrophic water. For ACCO, the average removal efficiency for chlorophyll a of 90.5% was achieved at an ozone dosage of 0.2mgL−1. The percentage removed increased to 95.8% at higher ozone dosages. The average residual chlorophyll a concentration in the outlet of the O3 and ACCO columns was 9.7 and 4.7μgL−1, respectively. O3 exhibited an approximately 36% increase in DOC concentration at an ozone dosage of 0.5mgL−1, while ACCO resulted in 53.5% and 76.0% DOC removal at ozone dosages of 0.5 and 1.0mgL−1, respectively (DOC residual <0.2mgL−1). The average color and turbidity removal for ACCO was about twice as much as achieved with ozonation. Pearson’s correlation showed good correlations between chlorophyll a attenuation and UV254, turbidity and color reduction by both processes. Univariate analysis of the variance revealed that turbidity as the best surrogate to predict chlorophyll a removal in the O3 process and UV254 and turbidity as the best surrogates to predict chlorophyll a removal in the ACCO process. Application of the ACCO process could be regarded as a promising advanced oxidation process for algae lysis and elimination of their metabolites.