Degradation of alachlor and pyrimethanil by combined photo-Fenton and biological oxidation

• Published in: Journal of hazardous materials 2008-06, Vol.155 (1), p.342-349
• Main Authors: Ballesteros Martín, M.M., Sánchez Pérez, J.A., García Sánchez, J.L., Montes de Oca, L., Casas López, J.L., Oller, I., Malato Rodríguez, S.
• Format: Article
• Language: English
• Subjects: Acetamides - chemistry; Acetamides - metabolism; Acetamides - radiation effects; Acetamides - toxicity; Alachlor; Applied sciences; Biodegradability; Biodegradation, Environmental; Biological and medical sciences; Biotechnology; Catalysis; Catalytic reactions; Chemical engineering; Chemistry; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Fungicides, Industrial - chemistry; Fungicides, Industrial - metabolism; Fungicides, Industrial - radiation effects; Fungicides, Industrial - toxicity; General and physical chemistry; Herbicides - chemistry; Herbicides - metabolism; Herbicides - radiation effects; Herbicides - toxicity; Iron - chemistry; Methods. Procedures. Technologies; Others; Oxidation-Reduction; Photo-Fenton; Pollution; Pseudomonas putida; Pseudomonas putida - drug effects; Pseudomonas putida - growth & development; Pseudomonas putida - metabolism; Pyrimethanil; Pyrimidines - chemistry; Pyrimidines - metabolism; Pyrimidines - radiation effects; Pyrimidines - toxicity; Reactors; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Ultraviolet Rays; Various methods and equipments; Waste Disposal, Fluid - methods; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism; Water Pollutants, Chemical - radiation effects; Water Pollutants, Chemical - toxicity; Water Purification - methods
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2007.11.069

Biodegradability of aqueous solutions of the herbicide alachlor and the fungicide pyrimethanil, partly treated by photo-Fenton, and the effect of photoreaction intermediates on growth and DOC removal kinetics of the bacteria Pseudomonas putida CECT 324 are demonstrated. Toxicity of 30–120 mg L −1 alachlor and pyrimethanil has been assayed in P. putida. The biodegradability of photocatalytic intermediates found at different photo-treatment times was evaluated for each pesticide. At a selected time during batch-mode phototreatment, larger-scale biodegradation kinetics were analysed in a 12 L bubble column bioreactor. Both alachlor and pyrimethanil are non-toxic for P. putida CECT 324 at the test concentrations, but they are not biodegradable. A ∼100 min photo-Fenton pre-treatment was enough to enhance biodegradability, the biological oxidation response being dependent on the pesticide tested. The different alachlor and pyrimethanil respiration and carbon uptake rates in pre-treated solutions are related to change in the growth kinetics of P. putida. Reproducible results have shown that P. putida could be a suitable microorganism for determining photo-Fenton pre-treatment time.