Degradation of Microcystin - LR in the treatment of supply water in conventional system followed homogeneous photocatalysis (UV/H2O2)
DOI:
https://doi.org/10.6008/CBPC2179-6858.2021.008.0025Keywords:
Treatment, Cyanotoxin, Advanced Oxidative Process, Photolysis (UV/H2O2)Abstract
The objective of the present study was to evaluate the degradation of microcystin-LR in the treatment of water supply in conventional system followed by homogeneous photocatalysis (UV /H2O2). The optimal conditions for the conventional treatment were determined in jar test with the dosage (50 mg.L-1) of Aluminum Sulphate, initial pH (6.8) of coagulation and sedimentation time of 15 min. In these conditions, the coagulation, flocculation, sedimentation and filtration stages of the conventional water method were efficient in the removal of true color (80%) and turbidity (97%), not satisfactory to the removal of microcystin-LR. However, there was significant removal of this micropollutant by the advanced oxidative process. Of the six treatments performed in the photocatalytic reactor, only the one of 1000 mM concentration (UV / H2O2) reached the maximum value allowed No. 005/2017 Annex XX for potability standards after 15 minutes of oxidation. At 60 minutes of the process there was an 83.3% removal of the microcystin-LR for this same dosage of H2O2 that reached the approximate final value of 0.5 μg.L-1 of microcytin-LR. The method used to analyze the oxidation of microcystin-LR by HPLC-MS was highly sensitive and rapid in detecting fragments resulting from the oxidation of (UV / H2O2) by identifying the ADDA amino acid present in the analyte from the m / z 135 fragment and thus proving the effectiveness of the treatment. It is concluded that the combination of a conventional treatment followed by advanced oxidative process (AOP) applied to the treatment of water of a eutrophic reservoir is an effective and safe solution for obtaining potable water.
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