Biodegradability enhancement of a pesticide-containing bio-treated wastewater using a solar photo-Fenton treatment step followed by a biological oxidation process

This work proposes an efficient combined treatment for the decontamination of a pesticide-containing wastewater resulting from phytopharmaceutical plastic containers washing, presenting a moderate organic load (COD=1662–1960mgO2L−1; DOC=513–696mgCL−1), with a high biodegradable organic carbon fracti...

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Bibliographic Details
Published in:Water research (Oxford) 2012-10, Vol.46 (15), p.4599-4613
Main Authors: Vilar, Vítor J.P., Moreira, Francisca C., Ferreira, Ana C.C., Sousa, M.A., Gonçalves, C., Alpendurada, M.F., Boaventura, Rui A.R.
Format: Article
Language:English
Subjects:
anions
Applied sciences
Biodegradability
Biodegradation, Environmental
Biological oxidation
carbon
chemical oxygen demand
Chromatography, Liquid
containers
decontamination
detection limit
energy
Exact sciences and technology
hydrogen peroxide
inorganic ions
mineralization
oxidation
Oxidation-Reduction
Pesticide-containing wastewater
pesticides
Pesticides - metabolism
phytochemicals
plastics
Pollution
Solar photo-Fenton
Sunlight
surface water
Tandem Mass Spectrometry
washing
wastewater
Water Pollutants, Chemical - metabolism
Water treatment and pollution
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Summary:This work proposes an efficient combined treatment for the decontamination of a pesticide-containing wastewater resulting from phytopharmaceutical plastic containers washing, presenting a moderate organic load (COD=1662–1960mgO2L−1; DOC=513–696mgCL−1), with a high biodegradable organic carbon fraction (81%; BOD5=1350–1600mgO2L−1) and a remaining recalcitrant organic carbon mainly due to pesticides. Nineteen pesticides were quantified by LC–MS/MS at concentrations between 0.02 and 45mgL−1 (14–19% of DOC). The decontamination strategy involved a sequential three-step treatment: (a) biological oxidation process, leading to almost complete removal of the biodegradable organic carbon fraction; (b) solar photo-Fenton process using CPCs, enhancing the bio-treated wastewater biodegradability, mainly due to pesticides degradation into low-molecular-weight carboxylate anions; (c) and a final polishing step to remove the residual biodegradable organic carbon, using a biological oxidation process. Treatment performance was evaluated in terms of mineralization degree (DOC), pesticides content (LC–MS/MS), inorganic ions and low-molecular-weight carboxylate anions (IC) concentrations. The estimated phototreatment energy necessary to reach a biodegradable wastewater, considering pesticides and low-molecular-weight carboxylate anions concentrations, Zahn-Wellens test and BOD5/COD ratio, was only 2.3kJUVL−1 (45min of photo-Fenton at a constant solar UV power of 30Wm−2), consuming 16mM of H2O2, which pointed to 52% mineralization and an abatement higher than 86% for 18 pesticides. The biological oxidation/solar photo-Fenton/biological oxidation treatment system achieved pesticide removals below the respective detection limits and 79% mineralization, leading to a COD value lower than 150mgO2L−1, which is in agreement with Portuguese discharge limits regarding water bodies. [Display omitted] ► Phytopharmaceutical containers washing wastewater presents a mixture of pesticides. ► Photo-Fenton reaction enhances the pesticide-containing wastewater biodegradability. ► Pesticides degradation into low-molecular-weight carboxylate anions was very fast
ISSN:0043-1354
1879-2448
DOI:10.1016/j.watres.2012.06.038