untitled CCHHEEMMIICCAALL EENNGGIINNEEEERRIINNGG TTRRAANNSSAACCTTIIOONNSS VOL. 27, 2012 A publication of The Italian Association of Chemical Engineering Online at: www.aidic.it/cet Guest Editors: Enrico Bardone, Alberto Brucato, Tajalli Keshavarz Copyright © 2012, AIDIC Servizi S.r.l., ISBN 978-88-95608-18-1; ISSN 1974-9791 Biological Approaches to the Treatment of Saline Oily Waste(waters) Originated from Marine Transportation Giuseppe Mancinia, Simone Cappello*b, Michail M. Yakimovb, Andrea Polizzia, Michele Torregrossac a Department of Industrial and Mechanical Engineering, University of Catania, Viale Andrea Doria 6, 95125 Catania, Italy b Institute for coastal marine environment (IAMC) – CNR U.O.S. of Messina, Spianata San Raineri 86, 98121 Messina, Italy c Department of Civil, Evironmental and Aerospace Engineering, University of Palermo , V.le delle Scienze, 90128 Palermo, Italy simone.cappello@iamc.cnr.it Oily wastewater generated, in amounts of millions of tons per year, by ships mainly in engine-rooms (bilge waters) and by washing oil tanks (slops) create a major disposal problem throughout the world because of the persistence and accumulation of xenobiotic compounds in the environment. The high salinity levels (up to 25.000 p.p.m.) and the pollutants concentration limit the chances of discharge into the sewer systems and address the disposal of these waste(water)s to the sea. Tightening effluent regulations and consequent high energy and management costs has generated interest in the introduction of biological phases in the treatment of these wastewater. The objectives of this study were to evaluate the feasibility of using biological processes with purposely acclimated microorganism for the treatment of high salinity oily wastewaters (slops). Specifically both the bio-regeneration of the exhaust Granular Activated Carbons (GAC), loaded with a mixture of compounds occurring in slops, and a BioFilm Membrane BioReactor (BF-MBR) application were examined. Results proved the feasibility of using salt-adapted micro-organisms capable of degrading the main pollutants contained in slops. 1. Introduction Analysis of the microbial communities that take part in hydrocarbons biodegradation activities has been a challenge for microbiologists (MacNaughton et al., 1999) and identification and subsequent isolation of these organisms could provide relevant candidate taxa for subsequent bioaugmentation studies as single organism inocula or consortia. Recently many marine hydrocarbonoclastic bacteria have been isolated and their degradation potential has been investigated (Yakimov et al., 2004). Although bioremediation technologies are well established for the clean-up of chemical and/or petrochemical spills in marine environment, the role of these bacteria in high salinity and oily wastewater treatment plants remains unknown and the knowledge of the structure, composition and dynamic, as well as of the metabolic capability of the microbial community are still lacking. The 37 selection of microorganisms able to break down the hydrocarbons in the sludge into harmless by- products can be carried out directly in the biological phase or from “natural” oily polluted environment. Specifically, in MBR secondary treatment, which is generally performed by indigenous, water-borne micro-organisms in a managed habitat, the selection and identification of microbial consortia with high capability to degrade hydrocarbons is a primary step for the optimization of the process. Also bio- regeneration of the exhaust GAC, treating high salinity oily waste(water)s can be performed from marine oil-degrading bacteria. The use of these micro-organisms has to be investigated according to their ability to degrade oil and survive to the extreme salinity conditions. Among these bacteria Alcanivorax borkumensis, showed to play a pivotal role in the oil-spill bioremediation (Schneiker et al., 2006), presumably for its capacity to grow on many saturated petroleum fraction constituents and biogenic hydrocarbons such as straight-chain and branched alkanes, isoprenoids, phytane, pristine and long sidechain alkyl compounds (Schneiker et al., 2006). Significantly, Alcanivorax was found in low number in unpolluted waters, but in high abundances in oil-polluted waters and coastlines, where it may comprise 80-90% of the oil-degrading microbial community (Kasai et al., 2002). It was however observed as the growth of Alcanivorax, on crude oil, was not particularly rapid in comparison with other marine oil-degrading bacteria (e.g. Thalassolituus). Abundance of Alcanivorax was also observed in field and microcosm and mesocosm experiments involving the addition of nitrose and phosphorus fertilizers to stimulate microbial degradation of oil (Cappello et al., 2007). Different hypotheses were proposed to explain the predominance of this strain in polluted environment (Kasai et al., 2002). Genome analysis yield unprecedented insights into the bacterium’s capacity for (i) n-alkane degradation, including metabolism, biosurfactant production and biofim formation, (ii) scaveging of nutrients and cofactors in the oligotrophic marine environment and (iii) coping with various habitat- specific stress factor (Schneiker et al., 2006). In particular, the presence of specifics multiple systems for saturated hydrocarbon catabolism, namely two alkane hydroxylase systems AlkB1 and AlkB2 and three P450 cytochromes (Schneiker et al., 2006) was detected. Focusing on these issues the research work examined the feasibility of different treatments including: � the bio-regeneration of the exhaust carbons (GAC), saturated by high-pre-treated slops, in order to reduce the GAC regeneration costs. � An MBR process as secondary treatment for light-pre-treated slops. Both the two biological phases were operated by specific high salinity acclimated microorganisms. 2. Materials and methods 2.1 Format Grab samples were collected from a floating tank of an oil costal deposit in the Augusta harbour (Sicily). A simple gravity separation (2 h) was carried out on site to separate floating oil. About 1000 litres of the clarified slops were stored in a fridge at 4°C, in order to inhibit any biological activity. Analytical characterization and most of the experiments were carried out in the Environmental Engineering laboratory of the University Kore of Enna (Sicily) according to APHA (2005). Water for GAC saturation were pre-treated by coagulation-precipitation with Ferric Chloride (Mancini et al. 2010). 2.2 GAC saturation and Bioregeneration Saturation of GAC was carried out through continuous flow column filtration. The standard experiment utilized a column filled with GAC (23 cm of length) with an empty bed contact time (EBCT) ranging from 18 to 21.7 minutes in the different experiments. In each saturation run the 3.2-cm diameter column was packed with 20-30 mesh PicaHydro S23 GAC or Picabiol GAC. The flow rate ranged from 50.1 to 62.8 ml min-1. With the respect to TOC values the GAC was considered saturated after about twelve litres. Bach bioregeneration tests were carried out through a combination of slops, buffered nutrient (urea and biphasic ammonium <30% and vegetable substances <65%), activated sludge sampled from the biological section of the oily contaminated groundwater treatment plant of Gela Refinery (Sicily) and the bacterium Alcanivorax borkumensis strain SK2 (DSMZ 11573), which was added to the high salinity sludge (conductivity ≈14 mS cm-1). Loaded GAC was directly subjected to the recirculation of the mixture pre-emptively filtered on sand. Layout of the experimental setup is shown in Figure 1. 38 39 40 BF-MBR effluent showed little variation with an average value of 19.9 ± 2.3 mg L-1 and an average reduction of 72%. 1 10 100 1.000 10.000 19 /0 3 22 /3 23 /0 3 24 /0 3 25 /0 3 26 /0 3 29 /0 3 31 /0 3 01 /0 4 06 /0 4 07 /0 4 08 /0 4 09 /0 4 85% 90% 95% 100% COD permeate COD raw COD removal Washing C O D r em ov al (% ) C O D (m g L -1 ) Figure 3: COD concentrations in the permeate and COD removal efficiency. 4. Conclusions In this paper the feasibility of treating an emulsified oily wastewater (slop) of high salinity, TPH and COD values was verified through GAC and BF-MBR systems. The selection of salt-tolerant micro- organisms involved an adaptation of a specifically selected sludge joined to Alcanivorax borkumensis SK2 to high salt concentrations. Tests on bioregeneration of exhaust GAC, carried out in batch units gave encouraging results in terms of TPH and COD removal from saturated GAC. Results proved the biological mixture capability of removing efficiently the organic matter adsorbed on the GAC thus increasing the service-life of the GAC without removing GAC from the filter (with consequently reduced management costs). The results of the reported short experimental campaign during which the BF-MBR pilot plant was directly fed with almost raw wastewater (without chemical-physical pre-treatment), showed that this technology represents a reliable process for slop treatment. The high sludge retention time and high filtration efficiency in the system enabled a large part of TOC to be removed, allowing the limits imposed for discharge into the sea to be met. Some key issues however remain and need to be addressed in the application of GAC bioregeneration and BF-MBR processes to the treatment of slops including the reduction of membrane fouling by proper pre-treatment and the identification of the role of the specifically added Alcanivorax borkumensis. Although biological treatment is usually inhibited by high salt concentrations, results from the present research proved the feasibility of using salt-adapted micro-organisms consortia capable of degrading the main pollutants contained in these oily and salty contaminated waters. Acknowledgments This project was partially funded by the Italian Ministry of Education, University and Research (MIUR), through the program “Research Program of Relevant National Interest”, PRIN 2007PM3TJM_002 (Project title: Water bodies protection from xenobiotic compounds: new methods for the analysis, the control and the treatment in civil and industrial wastewaters). 41 The authors sincerely wish to thanks the Pontoni S.r.l. service staff, operating in the Augusta Harbor (Sicily), for their kind and essential cooperation. The authors especially want to honour “The Chief”, Domenico Settipani who died in an unexpected accident on work on Monday, 23rd May 2011. The authors also wish to thanks Dr. Alessandro Monti and General Electric (Power & Water) for kindly providing the membrane for the MBR experiments. References Aktas O., Cecen F., 2007, Bioregeneration of activated carbon: a review, International Biodeterioration & Biodegradation 59, 257-272 APHA, AWWA, WEF, XXI Eds., 2005, Standard Methods for the Examination of Water and Wastewater. APHA, Washington, USA Cappello S., Caruso G., Zampino D., Monticelli L.S., Maimone G., Denaro R., Tripodo B., Troussellier M., Yakimov M.M., Giuliano L., 2007, Microbial community dynamics during assays of harbour oil spill bioremediation: a microscale simulation study, Journal Applied Microbiology, 102(1), 184-194 Goeddertz J.G., Matsumoto M.R., Weber A.S., 1988, Offline bioregeneration of granular activated carbon, Journal of Environmental Engineering 114, 1063–1076 Kasai Y., Kishira H., Sasaki T. , Syutsubo K., Watanabe K., Harayama S., 2002, Predominant growth of Alcanivorax strains in oil-contaminated and nutrient-supplemented seawater, Environ Microbiol 4, 141-147 MacNaughton S.J., Stephen J. R., Venosa A. D., Davis G. A., Chang Y. J., White D. C., 1999, Microbial population changes during bioremediation of an experimental oil spill, Appl Environ Microbiol 65, 3566-3574. Mancini G., Lanciotti E., Bruno M., 2010, Chemical-physical and biological treatment of high salinity wastewaters contaminated by oily xenobiotic compounds, Chemical Engineering Transactions vol.20, Eds Enrico Bardone Aurelio Viglia AIDIC Servizi S.r.L. Schneiker S., Martins dos Santos V.A., Bartels D., Bekel T., Brecht M., Buhrmester J., Chernikova T.N., Denaro R., Ferrer M., Gertler C. et al., 2006, Genome sequence of the ubiquitous hydrocarbondegrading marine bacterium Alcanivorax borkumensis, Nat Biotechnol 24, 997-1004 Torregrossa M., Viviani G., Mancini G., Di Trapani D., Di Bella G., Capodici M., 2010, High salinity slops treatment through a biofilm-MBR inoculated with halophilic bacteria, In: IWA Regional Conference and Exhibition on Membrane Technology and Water Reuse (IWA-MTWR-2010). Istanbul, 18,22-10-2010 Yakimov M.M., Gentile G., Bruni V., Cappello S. , D’Auria G., Golyshin P.N., Giuliano L., 2004, Crude oil-induced structural shift of coastal bacterial communities of Rod Bay (Terra Nova Bay, Ross Sea, Antarctica) and characterization of cultured cold-adapted hydrocarbonoclastic bacteria, FEMS Microbiology Ecology 49(3), 419-432. 42