UV/H2O2/O3 removal efficiency and characterization of algae-derived organic matter and odorous substances

Abstract

Algal organic matter (AOM) released from the metabolic processes of alga is an important source/precursor for toxic substances, thus it has aroused major environmental concerns due to its threat to safe water supplies. In this study, the algae Anabaena was selected as the target species, and a UV/H2O2/O3 advanced oxidation process (AOP) was used for AOM degradation. Overall, the intracellular organic matter (IOM) of Anabaena was mainly composed of soluble microbial metabolites, tyrosin and tryptophan, while the extracellular organic matter (EOM) mainly contained fulvic-acid and humic-acid substances, soluble microbial metabolites. The AOM mainly contained odorous substances such as cyclocitral, ionone, isophorone and a small amount of geosmin (GSM). Low molecular weight and hydrophobic components produced the highest formation potential of trihalomethane (THMFP) and dichloroacetonitrile (DCANFP). The Trichloromethane formation potential (TCMFP) of the different molecular weight (MW) components was higher than the standard for drinking water (> 60 μg/L), while the cytotoxicity of DCANFP was much higher than that of THMFP. The degradation efficiency of the UV/H2O2/O3 technology for cyclocitral was significant, but it could not effectively reduce the TCMFP and DCANFP. After treatment with UV/H2O2/O3, the EEM intensity of organic matter in each area decreased, and the biodegradability of AOM improved.