Kinetics of Microcystin-LR Removal in a Real Lake Water by UV/HO Treatment and Analysis of Specific Energy Consumption.

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. 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/HO was applied to a real lake water to remove MC-LR. The kinetics of the UV/HO were compared with those of UV and HO showing the following result: UV/HO > UV > HO. Within the range of HO tested (0-0.9 mM), the results showed that HO concentration and the removal kinetics followed an increasing quadratic relation. By increasing the initial concentration of HO, the consumption of oxidant also increased but, in terms of MC-LR degraded for HO 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) in which the presence of high amounts of the toxin slowed down the process. Operating with UV fluence lower than 950 mJ cm, UV alone minimized the specific energy consumption required. UV/HO (0.3 mM) and UV/HO (0.9 mM) were the most advantageous combination when operating with UV fluence of 950-1400 mJ cm and higher than 1400 mJ cm, respectively.