Integrated Principal Component Analysis of Microcystis aeruginosa Dissolved Organic Matter and Assessment of UV-C Pre-Treatment on Cyanobacteria-Containing Water

The intrinsic characteristic of chromophoric dissolved organic matter (CDOM) and bioactivity materials derived from toxic Microcystis aeruginosa was investigated. Fluorescence excitation emission matrix combined with parallel factor analysis (EEM-PARAFAC) determined six CDOM components, and principal component analysis (PCA) identified two integrated principle factors. PCA factor 1 mainly represented the intracellular and extracellular microbial active components, and factor 2 represented the extracellular residuals and degraded products. These two PCA factors accounted for 53 and 31% of the variance in nine parameters distributions, and were used to assess the variation pattern of DOM. The variation tendencies of PCA factors in experiments using single UV-C (254nm), UV-C/H₂O₂, UV-C/HCO3-, UV-C/NO3-, and UV-C/humic acid were estimated. Photolysis and photo-oxidation were dominating processes in single UV-C irradiation, and H₂O₂ improved photo-oxidation, resulting in high efficient removal of intracellular DOM and extracellular DOM. The presences of HCO3-, NO3- and humic acid had negative effects on the degradation of extracellular DOM, but little influence on intracellular DOM. Results revealed that UV-C/H₂O₂ can be considered as an option for the pretreatment of cyanobacteria-contained water, and EEM-PARAFAC-PCA can be applied to simplify multiple parameters in water treatment process, which would be benefit to water quality monitoring and management.