Kinetics of Microcystin-LR Removal in a Real Lake Water by UV/H2O2 Treatment and Analysis of Specific Energy Consumption

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.

A Summer of Cyanobacterial Blooms in Belgian Waterbodies: Microcystin Quantification and Molecular Characterizations

“…This treatment can eliminate the bloom and MCs but needs to be optimized based on bloom density and the quantity of toxins. For toxin quantification and assistance to prevention, analytical methods, such as the one presented in this paper, would be suitable [97][98][99][100][101][102][103][104][105]. Approaches such as flock lock or flock sink techniques could be a viable solution to prevent bloom incidence by capturing phosphorous on the bottom of larger waterbodies with a greater depth.…”

Photoelectrocatalysis on TiO2 meshes: different applications in the integrated urban water management

“…In recent years, the application of advanced oxidation processes (AOPs) on waters is gaining interest (Vilar et al 2017 ). In fact, the production of highly reactive OH• proved to effectively remove persistent organic pollutants and recalcitrant substances (Sorlini et al 2020 ). Among the AOPs, the application of photoelectrocatalysis (PEC) on waters is still at an early stage of study, but there are several examples of laboratory-scale applications (Wei et al 2017 ; Garcia-Segura and Brillas 2017 ; Fernández-Domene et al 2018 ; Brugnera et al 2019 ).…”

Removal of Cyanobacteria and Cyanotoxins in Waters

“…Three other papers address different advanced oxidation processes used to remove cyanotoxins [7][8][9]. Advanced oxidation processes involve a set of oxidative water treatments, including treatment with UV-O 3 , UV-H 2 O 2 , the Fenton process, the photo-Fenton process, and nonthermal plasmas as well as sonolysis, photocatalysis, and radiolysis, all based on the production of powerful, highly reactive oxidants.…”

“…The authors also found that the system's outstanding performance derives from the excellent photocatalytic performance and the high chemical and photochemical stability of Al-doped ZnO nanoparticles under visible-light irradiation with LEDs [8]. In another study, Sorlini et al [9] investigated the viability of using UV-H 2 O 2 to treat microcystin-LR, particularly by analyzing specific energy consumption in the waters of Lake Iseo in the Province of Brescia, Lombardy, Italy. Those authors aimed to preliminarily study the effectiveness of UV-H 2 O 2 on real water with respect to water matrix effects in order to clarify how the type of oxidant influences kinetics by analyzing the effects of the initial microcystin-LR concentration and the H 2 O 2 dosage.…”

“…Those authors aimed to preliminarily study the effectiveness of UV-H 2 O 2 on real water with respect to water matrix effects in order to clarify how the type of oxidant influences kinetics by analyzing the effects of the initial microcystin-LR concentration and the H 2 O 2 dosage. The authors also examined the total specific energy consumption of UV-H 2 O 2 compared to UV treatment to determine the optimal operational conditions [9]. Although the authors suggest the potential of using those three advanced oxidation processes to remove various cyanotoxins, unrealistic laboratory settings and conditions that allow the treatment of small volumes of water with highly energy-intensive lamps underscore some of the challenges of applying those technologies in the near future.…”