title: Efficient removal of microcystin-LR by UV-C/H₂O₂ in synthetic and natural water samples.
abstract: The destruction of the commonly found cyanobacterial toxin, microcystin-LR (MC-LR), in surface waters by UV-C/H(2)O(2) advanced oxidation process (AOP) was studied. Experiments were carried out in a bench scale photochemical apparatus with low pressure mercury vapor germicidal lamps emitting at 253.7 nm. The degradation of MC-LR was a function of UV fluence. A 93.9% removal with an initial MC-LR concentration of 1 μM was achieved with a UV fluence of 80 mJ/cm(2) and an initial H(2)O(2) concentration of 882 μM. When increasing the concentration of MC-LR only, the UV fluence-based pseudo-first order reaction rate constant generally decreased, which was probably due to the competition between by-products and MC-LR for hydroxyl radicals. An increase in H(2)O(2) concentration led to higher removal efficiency; however, the effect of HO scavenging by H(2)O(2) became significant for high H(2)O(2) concentrations. The impact of water quality parameters, such as pH, alkalinity and the presence of natural organic matter (NOM), was also studied. Field water samples from Lake Erie, Michigan and St. Johns River, Florida were employed to evaluate the potential application of this process for the degradation of MC-LR. Results showed that the presence of both alkalinity (as 89.6-117.8 mg CaCO(3)/L) and NOM (as ∼2 to ∼9.5 mg/L TOC) contributed to a significant decrease in the destruction rate of MC-LR. However, a final concentration of MC-LR bellow the guideline value of 1 μg/L was still achievable under current experimental conditions when an initial MC-LR concentration of 2.5 μg/L was spiked into those real water samples.
authors.affiliation: Environmental Engineering and Science Program, University of Cincinnati, 705 Engineering Research Center, Cincinnati, OH 45221-0012, USA.
authors.forename: Xuexiang
authors.initials: X
authors.lastname: He
authors.forename: Miguel
authors.initials: M
authors.lastname: Pelaez
authors.forename: Judy A
authors.initials: JA
authors.lastname: Westrick
authors.forename: Kevin E
authors.initials: KE
authors.lastname: O'Shea
authors.forename: Anastasia
authors.initials: A
authors.lastname: Hiskia
authors.forename: Theodoros
authors.initials: T
authors.lastname: Triantis
authors.forename: Triantafyllos
authors.initials: T
authors.lastname: Kaloudis
authors.forename: Mihaela I
authors.initials: MI
authors.lastname: Stefan
authors.forename: Armah A
authors.initials: AA
authors.lastname: de la Cruz
authors.forename: Dionysios D
authors.initials: DD
authors.lastname: Dionysiou
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry* / Q000528:radiation effects; D000087522:Cyanobacteria Toxins; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008387:Marine Toxins / Q000737:chemistry* / Q000528:radiation effects; D052998:Microcystins / Q000737:chemistry* / Q000528:radiation effects; D010084:Oxidation-Reduction; D010782:Photolysis; D014466:Ultraviolet Rays; D018508:Water Purification / Q000379:methods*; D060753:Water Quality
chemical_list: D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D008387:Marine Toxins; D052998:Microcystins; D006861:Hydrogen Peroxide; C057862:cyanoginosin LR