Removal of Microcystin-LR from Drinking Water Using a System Involving Oxidation and Adsorption

• Published in: Water, air, and soil pollution Vol. 228; no. 9; p. 1
• Main Authors: Lopes, Wilton S., Buriti, Josué S., Cebalos, Beatriz S. O., Sousa, José T., Leite, Valderi D., Vieira, Fernando F.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.09.2017; Springer; Springer Nature B.V
• Subjects: Activated carbon; Adsorption; Amino acids; Atmospheric Protection/Air Quality Control/Air Pollution; By-products; Capacity; Climate Change/Climate Change Impacts; Coagulation; Color; Colour; Drinking water; Earth and Environmental Science; Environment; Environmental monitoring; Eutrophic environments; Eutrophic waters; Eutrophication; Flocculation; Flow rates; Flow velocity; Hydrogen peroxide; Hydrogeology; Legislation; Mass spectrometry; Mass spectroscopy; Microcystin-LR; Microcystins; Oxidation; Oxidation-reduction reactions; pH effects; Pollutant removal; Removal; Scale (corrosion); Sedimentation; Sedimentation & deposition; Soil Science & Conservation; Turbidity; Water purification; Water Quality/Water Pollution; Water treatment; Bloom-forming cyanobacteria; Granular activated carbon from palm (dendê) coconut shells; Microcystin-LR; Fenton oxidation; Coagulation
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-017-3504-4

The aim of the present study was to evaluate the efficiency of removal of microcystin-LR from drinking water using a three-stage bench-scale treatment comprising Fenton oxidation/coagulation/flocculation/sedimentation, filtration through a sand column (15 cm bed), and adsorption onto a granular activated carbon (GAC) column with 15-cm (GAC1) or 20-cm bed (GAC2). Optimal first-stage conditions were determined to be FeSO 4 ∙7H 2 O 0.054 mM, H 2 O 2 0.162 mM, coagulation pH 8.4, sedimentation time 15 min, and flow rate 2 L h −1 . Under these conditions, water turbidity was reduced from 5.8 to 3.0 uT, apparent color from 115 to 81 uH, and the concentration of microcystin-LR from 18.52 to 9.59 μg L −1 . Column GAC2 was more efficient than GAC1, as shown by the higher adsorption capacity (4.15 μg g −1 ) and lower carbon usage rate (1.70 g L −1 ). Microcystin breakthrough occurred after 2 h of operation with GAC1 column and after 6 h with GAC2 column, and the greater efficiency of the latter column was confirmed by the high qe (4.15 μg g −1 ) and low CUR (1.70 g L −1 ) values attained. The results demonstrate that adsorption on a GAC column plays an essential role in reducing the concentration of microcystin-LR to levels compatible with current legislation. By-products of the Fenton oxidation of microcystin-LR were analyzed by mass spectrometry, and the ADDA amino acid present in the analyte was identified from its characteristic fragment at m / z 135. It is concluded that the combination of Fenton oxidation and adsorption on a GAC column represents a viable option for purifying eutrophic water containing high concentrations of microcystin-LR.