A reliable monitoring of the biocompatibility of an effluent along an oxidative pre-treatment by sequential bioassays and chemical analyses

• Published in: Water research (Oxford) Vol. 43; no. 3; pp. 784 - 792
• Main Authors: Amat, A.M., Arques, A., García-Ripoll, A., Santos-Juanes, L., Vicente, R., Oller, I., Maldonado, M.I., Malato, S.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-02-2009; Elsevier
• Subjects: activated sludge; Applied sciences; bioassays; Biodegradability; Biodegradation, Environmental - radiation effects; Biological Assay - methods; chemical analysis; chemical oxygen demand; effluents; Exact sciences and technology; gas chromatography; Hydrogen Peroxide - chemistry; Iron - chemistry; mass spectrometry; Other industrial wastes. Sewage sludge; Oxidation-Reduction - radiation effects; pesticide mixtures; Pesticides; Pesticides - chemistry; Photo-Fenton; Photochemical Processes - radiation effects; photochemistry; Pollution; pretreatment; Reproducibility of Results; solar radiation; Sunlight; Toxicity; Toxicity Tests; Vibrio fischeri; Waste Disposal, Fluid - methods; Wastes; wastewater treatment; Water treatment and pollution; Sunlight; Photo-Fenton; Biodegradability; Toxicity; Pesticides; Activated sludge; Chemical analysis; Bioassay; Pollutant behavior; Detoxification; Biological purification; Surveillance; Detection limit; Fenton reaction; Oxidation; Waste water purification; Solar radiation; Photooxidation; Organic compounds; Photochemical degradation
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2008.11.017

A new approach to assess biocompatibility of an effluent, based on combination of different bioassays and chemical analyses, has been tested using a mixture of four commercial pesticides treated by a solar photo-Fenton as target effluent. A very fast elimination of the pesticides occurred (all of them were below detection limit at
t
30W
=
36
min), but mineralisation was a more time-consuming process, due to the formation of organic intermediates and to the presence of solvents, as shown by GC–MS analysis. Measurements based on activated sludge indicated that detoxification was coincident with the removal of the active ingredients, while more sensitive
Vibrio fischeri bacterium showed significant toxicity until the end of the experiment, although the effluent might be compatible with biological processes. Biodegradability of the solutions was enhanced by the photochemical process, to reach BOD
5/COD ratios above 0.8. Longer time bioassays, such as the Zahn–Wellens' test, support the applicability of coupling photochemical with activated sludge-based biological processes to deal with these effluents.