Simultaneous abatement of organics (2,4-dichlorophenoxyacetic acid) and inactivation of resistant wild and laboratory bacteria strains by photo-induced processes in natural groundwater samples

• Published in: Solar energy Vol. 171; pp. 761 - 768
• Main Authors: Alvear-Daza, John J., Sanabria, Janeth, Rengifo Herrera, Julián A., Gutierrez-Zapata, Hector M.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.09.2018; Pergamon Press Inc
• Subjects: 2,4-D; Abatement; Acid resistance; Bacteria; Combined treatment; Deactivation; Dichlorophenoxyacetic acid; Dissolved organic matter; Drinking water; E coli; Groundwater; Groundwater pollution; Hydrogen peroxide; Inactivation; Iron; Irradiation; Klebsiella; Microorganisms; Organic chemicals; Oxides; Photo-fenton; Photochemicals; Photolysis; Photovoltaics; Solar energy; Solar water detoxification; Solar water disinfection; Strains (organisms); Sunlight; Ultraviolet radiation; Viability; Well waters; Drinking water; Solar water disinfection; Well waters; Solar water detoxification; Photo-fenton
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2018.07.026

[Display omitted] •UV lamp and natural sunlight in presence of H2O2 led to the bacteria inactivation.•Coupled system was efficient removing 2,4-D and wild bacteria in natural well water.•Low sunlight irradiation caused a detrimental effect on bacteria inactivation.•Photo-Fenton and other photo-induced reactions led to the 2,4-D and bacteria removal. Simultaneous abatement of 2,4-dichlorophenoxyacetic acid (2,4-D at 70 µg L−1), Escherichia coli and Klebsiella pneumoniae (laboratory and wild strains) cells from real groundwater samples containing natural iron concentrations (∼0.3 mg L−1) was studied by addition of H2O2 (10 mg L−1) using a 18-L compound parabolic collector-CPC solar reactor (under natural sunlight irradiation 150,000 J m−2) equipped with a UV-(A + B + Visible) lamp (15 W: UV-B and UV-A intensities were 0.74 and 6.47 W m−2 respectively) powered by a photovoltaic panel. Viability of E. coli K12 and K. pneumoniae laboratory strains at high initial concentrations of 106–107 cells mL−1 (followed by DVC-FISH) dropped 4.69 and 2.18 Logs, respectively after 30 min t30W of combined UV-A + B-Visible lamps and sunlight irradiation (SL + UV + H2O2). Moreover, the initial 2,4-D concentration underwent a strong reduction reaching concentrations below the detection limit after 5 min t30W of SL + UV + H2O2 treatment. Regarding real wild bacteria strains often present in natural well waters, which were at low initial concentrations, total culturability (initial concentration 101 CFU mL−1) and viability (initial concentration 102–103 cells mL−1) reductions were reached after 30 min (t30W) of combined treatment. Participation of several photochemical and dark events such as photocatalysis (by iron hydro-oxides and other metal oxides naturally present), Fenton and photo-Fenton (by natural dissolved iron), UV-A + B/NO3−, Dissolved organic matter (DOM)/UV + Vis and UV-B photolysis of H2O2 are suggested as responsible of simultaneous 2,4-D abatement and microbial inactivation in natural groundwater samples.