Abstract
The hepatotoxin microcystin-LR (MC-LR) represents one of the most toxic cyanotoxins for human health. Considering its harmful effect, the World Health Organization recommended a limit in drinking water (DW) of 1 µg L−1. Due to the ineffectiveness of conventional treatments present in DW treatment plants against MC-LR, advanced oxidation processes (AOPs) are gaining interest due to the high redox potential of the OH• radicals. In this work UV/H2O2 was applied to a real lake water to remove MC-LR. The kinetics of the UV/H2O2 were compared with those of UV and H2O2 showing the following result: UV/H2O2 > UV > H2O2. Within the range of H2O2 tested (0–0.9 mM), the results showed that H2O2 concentration and the removal kinetics followed an increasing quadratic relation. By increasing the initial concentration of H2O2, the consumption of oxidant also increased but, in terms of MC-LR degraded for H2O2 dosed, the removal efficiency decreased. As the initial MC-LR initial concentration increased, the removal kinetics increased up to a limit concentration (80 µg L−1) in which the presence of high amounts of the toxin slowed down the process. Operating with UV fluence lower than 950 mJ cm−2, UV alone minimized the specific energy consumption required. UV/H2O2 (0.3 mM) and UV/H2O2 (0.9 mM) were the most advantageous combination when operating with UV fluence of 950–1400 mJ cm−2 and higher than 1400 mJ cm−2, respectively.
Highlights
Microcystin-LR (MC-LR) is a hepatotoxin produced by cyanobacteria such as Microcystis aeruginosa, Planktothrix, Nostoc and Anabaea and represents one of the most common and most toxic cyanotoxins for human health [1,2,3]
Conditions: MC-LR0 = 50 μg L−1 ; pH =−1 7.5 interval corresponding to the same UV fluence of the other tests
The results show that the total specific energy consumption (EEO, total ) followed two different behaviors depending on the UV fluence considered and the H2 O2 dosed (Figure A4 in the Appendix A)
Summary
Microcystin-LR (MC-LR) is a hepatotoxin produced by cyanobacteria such as Microcystis aeruginosa, Planktothrix, Nostoc and Anabaea and represents one of the most common and most toxic cyanotoxins for human health [1,2,3]. Cyanotoxins can interact and alter different parts of human metabolism with consequent effects on health of varying severity. All cyanobacteria genera can produced cyanotoxins belonging to the group of Lipopolysaccharides, which have only a potential irritating effect on the tissues they have come into contact with [6]. Several studies highlighted the effects on liver tissue in humans exposed chronically to MC-LR [7,8,9]
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