Process water from nuclear fuel recovery unit operations contains a variety of toxic organic compounds. The use of decontamination reagents such as together with phenolic tar results in wastewater with a high content of chlorophenols. In this study, the extent of dehalogenation of toxic aromatic compounds was evaluated using a photolytic advanced oxidation process (AOP) followed by biodegradation in the second stage. A hard-to-degrade toxic pollutant, 4-chlorophenol (4-CP), was used to represent a variety of recalcitrant aromatic pollutants in effluent from the nuclear industry. A UV-assisted AOP/bioreactor system demonstrated a great potential in treatment of nuclear process wastewater and this was indicated by high removal efficiency ( %) under various 4-CP concentrations. Adding hydrogen peroxide ( ) as a liquid catalyst further improved biodegradation rate but the effect was limited by the scavenging of radicals under high concentrations of . 1. Introduction Process water from nuclear fuel recovery unit operations contains a variety of toxic organic compounds. The use of decontamination reagents such as CCl4 together with phenolic tar results in wastewater with a high content of chlorophenols. Chlorophenols are compounds of serious environmental concern due to their toxic impacts and discharge from a wide range of industrial sources. A large number of chlorophenol derivatives are refractory in nature rendering them resistant to biological degradation. The recalcitrance of these compounds results from the carbon-hydrogen bond, which is cleaved with great difficulty [1]. Due to their stability, halogenated phenols tend to accumulate in higher-order organisms. In summary, a large component of nuclear waste contains organic waste consisting of alcohols and phenolics. Current treatment processes for the removal of halogenated organic compounds involve dehalogenation using salts followed by chemical oxidation of the unhalogenated form [2]. The chemical process results in the production of harmful byproducts that require further disposal [3]. Among the alternative methods to the chemical treatment processes are the biological processes using specialized species of chlorophenol degrading organisms, oxidative reaction using AOP and photocatalysis [4]. However, when used alone AOPs still produce harmful byproducts and may be energy intensive. Lately, more interest has been directed towards finding solutions that involve the use of cultures of microorganisms to treat contaminated sediments and water impacted by nuclear waste [5]. The biological technology is
References
[1]
H. Movahedyan, A. Assadi, and M. M. Amin, “Effects of 4-chlorophenol oadings on acclimation of biomass with optimized fixed time sequencing batch reactor,” Iranian Journal of Environmental Health, Science and Engineering, vol. 5, no. 4, pp. 225–234, 2008.
[2]
J. E. T. van Hylckama Vlieg and D. B. Janssen, “Formation and detoxification of reactive intermediates in the metabolism of chlorinated ethenes,” Journal of Biotechnology, vol. 85, no. 2, pp. 81–102, 2001.
[3]
V. Sarria, M. Deront, P. Perinnger, and C. Pulgarin, “Degradation of a biorecalcitrant dye precursor present in industrial wastewaters by a new integrated iron(III) photoassisted-biological treatment,” Applied Catalysis B, vol. 40, no. 3, pp. 231–246, 2003.
[4]
H. Ku？i？, N. Koprivanac, A. L. Bo？i？, and I. Selanec, “Photo-assisted Fenton type processes for the degradation of phenol: a kinetic study,” Journal of Hazardous Materials, vol. 136, no. 3, pp. 632–644, 2006.
[5]
T. Barkay and J. Schaefer, “Metal and radionuclide bioremediation: issues, considerations and potentials,” Current Opinion in Microbiology, vol. 4, no. 3, pp. 318–323, 2001.
[6]
A. Vogelpohl and S.-M. Kim, “Advanced oxidation processes (AOPS) in wastewater treatment,” Journal of Industrial and Engineering Chemistry, vol. 10, no. 1, pp. 33–40, 2004.
[7]
T. Coenye, E. Falsen, M. Vancanneyt, et al., “Classification of Alcaligenes faecalis-like isolates from the environment and human clinical samples as Ralstonia gilardii sp. nov,” International Journal of Systematic Bacteriology, vol. 49, no. 2, pp. 405–413, 1999.
[8]
E. Metcalf, Wastewater Engineering: Treatment and Reuse, McGraw-Hill, Boston, Mass, USA, 4th edition, 2003.
[9]
S. Pallerla and R. P. Chambers, “Reactor development for biodegradation of pentachlorophenol,” Catalysis Today, vol. 40, no. 1, pp. 103–111, 1998.
[10]
G. E. Briggs and J. B. Haldane, “A note on the kinetics of enzyme action,” Biochemical Journal, vol. 19, no. 2, pp. 338–339, 1925.
[11]
J. Wen, H. Li, J. Bai, and Y. Jiang, “Biodegradation of 4-chlorophenol by Candida albicans PDY-07 under anaerobic conditions,” Chinese Journal of Chemical Engineering, vol. 14, no. 6, pp. 790–795, 2006.
[12]
M. Pera-Titus, V. García-Molina, M. A. Ba？os, J. Giménez, and S. Esplugas, “Degradation of chlorophenols by means of advanced oxidation processes: a general review,” Applied Catalysis B, vol. 47, no. 4, pp. 219–256, 2004.
[13]
B. Xu, N.-Y. Gao, X.-F. Sun, et al., “Photochemical degradation of diethyl phthalate with ,” Journal of Hazardous Materials, vol. 139, no. 1, pp. 132–139, 2007.
[14]
D. Suryaman, K. Hasegawa, and S. Kagaya, “Combined biological and photocatalytic treatment for the mineralization of phenol in water,” Chemosphere, vol. 65, no. 11, pp. 2502–2506, 2006.
[15]
E. Sahinkaya and F. B. Dilek, “Modeling chlorophenols degradations in sequencing batch reactors with instantaneous feed-effect of 2.4 DCP presences on 4-CP degradation kinetics,” Biodegradation, vol. 18, pp. 427–437, 2007.
[16]
S. S. Makgato and E. M. N. Chirwa, “Photoassisted biodegradation of halogenated breakdown products in nuclear fuel recovery process water—hybrid reaction process,” Chemical Engineering Transactions, vol. 17, pp. 1167–1172, 2009.
[17]
E. Brillas, C. Arias, P. L. Cabot, F. Centellas, J. A. Garrido, and M. Dodriguez, “Degradation of organic contaminants by advanced electrochemical oxidation methods,” Portugaliae Electrochimica Acta, vol. 24, pp. 159–189, 2006.
[18]
Y. Cheng, H. Sun, W. Jin, and N. Xu, “Photocatalytic degradation of 4-chlorophenol with combustion synthesized under visible light irradiation,” Chemical Engineering Journal, vol. 128, no. 2-3, pp. 127–133, 2007.
[19]
U. I. Gaya and A. H. Abdullah, “Heterogeneous photocatalytic degradation of organic contaminants over titanium dioxide: a review of fundamentals, progress and problems,” Journal of Photochemistry and Photobiology C, vol. 9, no. 1, pp. 1–12, 2008.
[20]
X. L. Hao, M. H. Zhou, and L. C. Lei, “Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water,” Journal of Hazardous Materials, vol. 141, no. 3, pp. 475–482, 2007.
[21]
R. J. A. L'Amour, E. B. Azevedo, S. G. F. Leite, and M. Dezotti, “Removal of phenol in high salinity media by a hybrid process (activated sludge + photocatalysis),” Separation and Purification Technology, vol. 60, no. 2, pp. 142–146, 2008.
[22]
H. Wang and J. Wang, “Electrochemical degradation of 4-chlorophenol using a novel Pd/C gas-diffusion electrode,” Applied Catalysis B, vol. 77, no. 1-2, pp. 58–65, 2007.
[23]
Y. Zhang, M. Zhou, X. Hao, and L. Lei, “Degradation mechanisms of 4-chlorophenol in a novel gas-liquid hybrid discharge reactor by pulsed high voltage system with oxygen or nitrogen bubbling,” Chemosphere, vol. 67, no. 4, pp. 702–711, 2007.
[24]
X. Li, J. W. Cubbage, and W. S. Jenks, “Photocataytic degradation of 4-chlorophenol,” Journal of Organic Chemistry, vol. 64, no. 23, pp. 8525–8536, 1999.
[25]
Ch. M. Du, J. H. Yan, and B. G. Cheron, “Degradation of 4-chlorophenol using a gas-liquid gliding arc discharge plasma reactor,” Plasma Chemistry and Plasma Processing, vol. 27, no. 5, pp. 635–646, 2007.
[26]
X. Yin, W. Bian, and J. Shi, “4-chlorophenol degradation by pulsed high voltage discharge coupling internal electrolysis,” Journal of Hazardous Materials, vol. 166, no. 2-3, pp. 1474–1479, 2009.
[27]
J. Theurich, M. Lindner, and D. W. Bahnemann, “Photocatalytic degradation of 4-chlorophenol in aerated aqueous titanium dioxide suspensions: a kinetic and mechanistic study,” Langmuir, vol. 12, no. 26, pp. 6368–6376, 1996.
[28]
I. Arslan-Alaton, T. Olmez-Hanci, B. H. Gursoy, and G. Tureli, “ /UV-C treatment of the commercially important aryl sulfonates H-, K-, J-acid and Para base: assessment of photodegradation kinetics and products,” Chemosphere, vol. 76, no. 5, pp. 587–594, 2009.
[29]
E. Lipczynska-Kochany and J. R. Bolton, “Flash photolysis/HPLC method for studying the sequence of photochemical reactions: applications to 4-chlorophenol in aerated aqueous solution,” Journal of Photochemistry and Photobiology A, vol. 58, no. 3, pp. 315–322, 1991.
[30]
W. Gaofeng, X. Hong, and J. Mei, “Biodegradation of chlorophenols: a review,” Chemical Journal on Internet, vol. 6, no. 10, pp. 1–67, 2004.
[31]
J. A. Field and R. Sierra-Alvarez, “Microbial degradation of chlorinated phenols,” Reviews in Environmental Science and Biotechnology, vol. 7, no. 3, pp. 211–241, 2008.
[32]
E. C. Catalkaya, U. Bali, and F. Sengiil, “Photochemical degradation and mineralization of 4-chlorophenol,” Environmental Science and Pollution Research, vol. 10, no. 2, pp. 113–120, 2003.
[33]
M. Y. Ghaly, G. Hartel, R. Mayer, and R. Haseneder, “Photochemical oxidation of p-chlorophenol by and photo-Fenton process. A comparative study,” Waste Management, vol. 21, no. 1, pp. 41–47, 2001.
[34]
I. Konya, S. Eker, and F. Kargi, “Mathematical modelling of 4-chlorophenol inhibition on COD and 4-chlorophenol removals in an activated sludge unit,” Journal of Hazardous Materials, vol. 143, no. 1-2, pp. 233–239, 2007.
[35]
P. Rechert, Computer Program for the Identification and Simulation of Aquatic Systems—AQUASIM 2.0: User Manual, Swiss Federal Institute for Environmental Science and Technology (EAWAG), Dübendorf, Switzerland, 1998.
[36]
Y. Jiang, J. Wen, L. Lan, and Z. Hu, “Biodegradation of phenol and 4-chlorophenol by the yeast Candida tropicalis,” Biodegradation, vol. 18, no. 6, pp. 719–729, 2007.
