title: Degradation of alachlor and pyrimethanil by combined photo-Fenton and biological oxidation.
abstract: 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 approximately 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.
authors.affiliation: Departamento de Ingeniería Química, Universidad de Almería, 04120 Almería, Spain.
authors.forename: M M
authors.initials: MM
authors.lastname: Ballesteros Martín
authors.forename: J A
authors.initials: JA
authors.lastname: Sánchez Pérez
authors.forename: J L
authors.initials: JL
authors.lastname: García Sánchez
authors.forename: L
authors.initials: L
authors.lastname: Montes de Oca
authors.forename: J L
authors.initials: JL
authors.lastname: Casas López
authors.forename: I
authors.initials: I
authors.lastname: Oller
authors.forename: S
authors.initials: S
authors.lastname: Malato Rodríguez
mesh_terms: D000081:Acetamides / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects / Q000633:toxicity; D001673:Biodegradation, Environmental; D005659:Fungicides, Industrial / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects / Q000633:toxicity; D006540:Herbicides / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects / Q000633:toxicity; D007501:Iron / Q000737:chemistry*; D010084:Oxidation-Reduction; D016958:Pseudomonas putida / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D011743:Pyrimidines / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects / Q000633:toxicity; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects / Q000633:toxicity; D018508:Water Purification / Q000379:methods
chemical_list: D000081:Acetamides; D005659:Fungicides, Industrial; D006540:Herbicides; D011743:Pyrimidines; D014874:Water Pollutants, Chemical; C000188:alachlor; C108337:pyrimethanil; D007501:Iron