ORIGINAL PAPER Aerobic fate and impact of canola oil in aquatic media Pablo Campo • Yuechen Zhao • Makram T. Suidan • Albert D. Venosa Received: 17 January 2011 / Accepted: 28 April 2011 / Published online: 19 May 2011 Ó Springer-Verlag 2011 Abstract The fate of canola oil in water under aerobic conditions was studied in respirometry tests. First-order biodegradation rates were estimated for a refined oil (commercial canola oil, CCO), 0.0037 h -1 , and for two synthetic oils, one prepared with mono-acid triacylglyce- rols (TAO) 0.0048 h -1 , and the other with free fatty acids and glycerol (FAO) 0.0038 h -1 . Two abiotic factors lim- ited substrate bioavailability: the autoxidation of the oleoyl chains and the insolubility of fully saturated triacylglyce- rols. In addition, the ecotoxic impact of the oils was assessed by Microtox Ò toxicity. For the acylglycerol oils, luminescent bacteria inhibition was not detected in the water phase, whereas solid-phase EC 50 values below 1.8% sample volume were measured. Toxicity was observed in the aqueous phase (EC 50 \ 16%) during the biodegrada- tion of FAO. In this case, however, solid-phase toxicity was extremely high at the beginning of the test (0.02%) but the toxicity dissipated 480 h into the experiment. Keywords Autoxidation  BOD  FOG  Microtox  Respirometry Introduction It has generally been claimed by the vegetable oil industry that the release of edible fats, oils, and greases (FOGs) into the environment does not impose an eco- logical or human health hazard. Nevertheless, according to the U.S. Environmental Protection Agency (USEPA), FOGs fall under the general definition of ‘‘oil’’ as specified by 40 CFR 112.2 and Clean Water Act Sec- tion 311(a)(1), and as such, they are required by regula- tion to be treated by the same safety and spill response protocols that are applied to petroleum oils (USEPA 1997). In fact, scientific literature has shown that release of FOGs into open seas, shorelines, or freshwater bodies can be as hazardous as spills of petroleum oil, causing comparable ecological and economic damage (Bucas and Saliot 2002). For instance, in January of 1991, 1500 tons of sunflower oil were spilled on the coast of North Wales, UK, as a consequence of the drifting and eventual wrecking of the merchant vessel (M.V.) Kimya. No response to the spill was initially made since it was assumed that indigenous microorganisms would degrade the vegetable oil without causing any further deleterious effect. The aftermath of the incident resulted in a very different scenario: the spilled oil underwent a polymeri- zation process, forming solid aggregates with sediments, and dramatically limiting the removal of the oil that remained on the impacted shoreline for more than 6 years (Mudge 1997). In 1975, prior to the above-cited incident, another cargo ship, the M.V. Lindenbank, released 10,000 tons of primarily palm oil and copra on Fannin Atoll in the central Pacific Ocean. This spill led to the death of fish, crustaceans, and mollusks and caused an algal bloom of Enteromorpha sp. and Ulva sp. (Russel and Carlson 1978). Moreover, recurring leaks of rapeseed oil located in the Vancouver harbor, BC, Canada ended with signif- icant bird mortality (Smith and Herunter 1989; Oil Spill Intelligence Report 1998, 1999). In fact, Mckelvey et al. (1980) considered the effects of edible oil spills on water P. Campo  Y. Zhao  M. T. Suidan (&) School of Energy, Environmental, Biological and Medical Engineering, University of Cincinnati, Cincinnati, OH 45221, USA e-mail: Makram.Suidan@uc.edu A. D. Venosa NRMRL USEPA, Cincinnati, OH, USA 123 Clean Techn Environ Policy (2012) 14:125–132 DOI 10.1007/s10098-011-0384-y