On the Use, and Reuse, of Polymers for the Treatment of Hydrocarbon Contaminated Water Via a Solid–liquid Partitioning Bioreactor George P. Prpich, Lars Rehmann, and Andrew J. Daugulis Dept. of Chemical Engineering, Queen’s University, Kingston, ON Canada K7L 3N6 DOI 10.1021/bp.14 Published online in Wiley InterScience (www.interscience.wiley.com). Aqueous environments contaminated with diesel components pose a threat to the native biota due to the intrinsically toxic nature of the many hydrocarbon compounds present. In the event of diesel being released into an aqueous environment it is imperative that the con- taminant is recovered in a rapid manner to ensure the safety of aquatic organisms as well as to maintain desired water quality. The research presented in this study investigates the potential of polymeric sorbents to recover diesel from a contaminated aqueous source. Ther- moplastic materials, such as styrene butadiene derived polymers, were shown to substan- tially reduce diesel levels in excess of 98% with 90% of this recoverable fraction being removed in less than 30 min. Recyclable materials, such as used automobile tires, were shown to obtain similar results with added potential benefit including lower cost and reuse of a waste material. The polymeric sorbents were also biologically regenerated and this was accomplished in a solid–liquid two-phase partitioning bioreactor, in which 65% of the initial diesel contamination was degraded within a 9 day period. The result of this work was the demonstration of a low cost, reusable remediation technology for the recovery, and destruc- tion of diesel from aqueous environments. Introduction Diesel fuel represents a significant environmental contami- nant originating from such sources as leaking underground storage tanks and transfer pipes as well as accidents at filling stations or during transportation. Diesel released into the environment is susceptible to migration, often resulting in the contamination of underground aquifers and receiving waters, such as lakes and rivers. 1 The presence of diesel in these aquatic environments has been shown to be detrimental to the natural biota 2–4 and therefore rapid recovery of diesel contaminant is imperative to ensure safety and survival of aquatic life. The application of sorbent materials represents a popular method for recovery of diesel from water. A general over- view by Adebajo et al. 5 outlined three main classes of sorb- ents that included inorganic materials, 6,7 natural organic materials, 8,9 and synthetic organic materials. 10 Desirable per- formance characteristics of these materials include high sorp- tive capacity, high rate of uptake, oil recovery from sorbent, and reusability of sorbent 5 however, in many instances these materials are limited in their ability to be regenerated. On the other hand, engineered thermoplastics represent a class of materials that satisfy the above criteria and may be rou- tinely and successfully regenerated via biological means. 9 Compared with traditional sorbent materials, engineered ther- moplastics are beneficial as they are capable of releasing sorbed contaminants under ambient conditions, are reusable and are non-biodegradable. Bioremediation offers a low cost, environmentally benign solution for treatment of diesel contaminated water. The lit- erature contains numerous reports describing the capacity of microbes to degrade hydrocarbons. 11–14 Although bioreme- diation may occur naturally in the environment, if feasible, accelerated biodegradation may occur in a bioreactor where growth conditions such as temperature, pH, and nutrient lev- els may be conveniently controlled. Studies have shown that under controlled conditions, mixed microbial populations are capable of degrading dilute concentration of diesels by up to 90%. 14,15 The motivation of this study was to demonstrate a low cost, reusable, remediation strategy for the treatment of die- sel contaminated water by combining the advantages of ther- moplastic sorbent materials, and accelerated bioremediation. Thermoplastic polymers were investigated as potential sorb- ents as these materials have been shown to effectively absorb organic molecules from water and soil. 16,17 The use of recy- clable thermoplastics, in particular used automobile tires, was studied to demonstrate the potential of a waste material to remediate a waste contaminant. Regeneration of the sor- bent material occurred in a solid–liquid two phase partition- ing bioreactor (TPPB) that contained a mixed microbial population of diesel degrading bacteria. The release of diesel from the sorbent material followed by its subsequent Correspondence concerning this article should be addressed to A. J. Daugulis at andrew.daugulis@chee.queensu.ca. Biotechnol. Prog. 2008, 24, 839844 839 V V C 2008 American Institute of Chemical Engineers