title: Comparison of experimental methods for determination of toxicity and biodegradability of xenobiotic compounds.
abstract: Different methods for determining the toxicity and biodegradability of hazardous compounds evaluating their susceptibility to biological treatment were studied. Several compounds including chlorophenols and herbicides have been evaluated. Toxicity was analyzed in terms of EC50 and by a simple respirometric procedure based on the OECD Method 209 and by the Microtox® bioassay. The values of EC50 obtained from respirometry were in all the cases higher than those from the Microtox® test. The respirometric inhibition values of chlorophenols were related well with the number of chlorine atoms and their position in the aromatic ring. In general, herbicides showed lower inhibition, being alachlor the less toxic from this criterion. For determination of biodegradability an easier and faster alternative to the OECD Method 301, with a higher biomass to substrate ratio is proposed. When this test was negative, the Zahn-Wellens one was performed in order to evaluate the inherent biodegradability. In the fast test of biodegradability, 4-chlorocatechol and 4-chlorophenol showed a complete biodegradation by an unacclimated sludge upon 48 h. These results together with their low respirometric inhibition, allow concluding that these compounds could be conveniently removed in a WWTP. Alachlor, 2,4-dichlorophenol, 2,4,6-trichlorophenol and MCPA showed a partial biodegradation upon 28 days by the Zahn-Wellens inherent biodegradability test.
authors.affiliation: Sección de Ingeniería Química, Facultad de Ciencias, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, 28049, Madrid, Spain. alicia.polo@uam.es
authors.forename: A M
authors.initials: AM
authors.lastname: Polo
authors.forename: M
authors.initials: M
authors.lastname: Tobajas
authors.forename: S
authors.initials: S
authors.lastname: Sanchis
authors.forename: A F
authors.initials: AF
authors.lastname: Mohedano
authors.forename: J J
authors.initials: JJ
authors.lastname: Rodríguez
mesh_terms: D048908:Aliivibrio fischeri / Q000187:drug effects / Q000502:physiology; D001673:Biodegradation, Environmental; D001681:Biological Assay / Q000379:methods; D057919:Biological Oxygen Demand Analysis / Q000379:methods*; D019149:Bioreactors; D002733:Chlorophenols / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D002851:Chromatography, High Pressure Liquid; D004787:Environmental Pollution / Q000517:prevention & control; D006540:Herbicides / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D020128:Inhibitory Concentration 50; D010100:Oxygen / Q000378:metabolism; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D018675:Toxicity Tests / Q000379:methods*; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity; D015262:Xenobiotics / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity
chemical_list: D002733:Chlorophenols; D006540:Herbicides; D012722:Sewage; D014874:Water Pollutants, Chemical; D015262:Xenobiotics; D010100:Oxygen