Enhancement of Ultraviolet Disinfection of Wastewater by High Pressure Water Jet Pretreatment: Preliminary Results and a New Approach
Publication: Journal of Environmental Engineering
Volume 135, Issue 10
Abstract
The shield or shadow effect of large particles on bacteria undergoing irradiation from ultraviolet light in effluent of treated wastewater would greatly reduce the effectiveness of ultraviolet disinfection. The objective of this work is to evaluate the newly proposed method of applying a high pressure water jet (HPWJ) as a pretreatment step in combination with ultraviolet irradiation to improve the disinfection efficiency of wastewater by breaking up the large particles (reducing the shield or shadow effects). Pretreatment experiments with two HPWJ units having different water pressure output (6.9 and 13.1 MPa) and nozzles were conducted in the study on primary clarifier overflow (PCO). The experiment results revealed that the particle size distributions (PSDs) in the test samples were apparently shifted toward the small size range and the total number of particles has been greatly increased after undergoing treatment with the HPWJ. In general it is assumed that bioparticles larger than a certain size are difficult to disinfect by ultraviolet. After the HPWJ treatment the relevant particle size range in the test samples of the PCO was reduced on average by half for tested HPWJ settings. Also, a primary comparison showed that under a similar amount of energy consumption, the HPWJ performed better than the ultrasonic method did in terms of effectively breaking up large particles. As expected, the changes of PSD notably affect the efficiency of ultraviolet disinfection as tested with the collimated beam. The E. coli and total coliform tests showed that pretreated PCO by the HPWJ enhanced the efficiency of ultraviolet disinfection by more than 1 log unit compared to treatment by ultraviolet alone when the ultraviolet dose was in the range. Multiple pretreatment with the HPWJ was also tested, which showed the advantage of breaking up slightly more particles, but with less enhancement of ultraviolet disinfection compared to a single pretreatment. This could possibly be due to the reduced ultraviolet transmission in the test sample caused by the presence of a larger number of suspended particles. The E. coli test results indicated that the well known “tailing region” of typical patterns of the ultraviolet dose-response curve was eliminated or decreased after the PCO was treated by HPWJ. The application of a HPWJ step might also be beneficial in terms of cost-effectiveness. With HPWJ pretreatment it only takes about one-third of the ultraviolet light exposure time to achieve the same disinfection results as ultraviolet treatment alone in the collimated beam test. The experimental results in this study showed some degree of variation for similar experiments. This is not unusual for this kind of study, due to many uncontrolled factors such as characteristics of tested PCO samples, random error in the microbiology tests and so on. However, these experiments clearly showed that the proposal of using the HPWJ to pre-treat wastewater could be a very attractive alternative to enhance ultraviolet disinfection efficiency.
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Acknowledgments
The support received from Environment Canada and Doug Doede, Jim Wood, John Gibson from National Water Research Institute and from Co-op students Mohammad-Reza Asarizadeh and Simon Morgan is greatly appreciated.
References
Barker, S., Oleszkiewicz, J., Madrid, E., and Gibson, D. (2004). “On-site collimated beam testing of secondary and blended effluent.” Proc., 77th Annual Technical Exhibition and Conf., Water Environment Federation, Alexandria, Va.
Blitz, J. (1967). Fundamentals of ultrasonics, Butterworth’s, London, U.K.
Botha, C. J., and Buckley, C. A. (1995). “Disinfection of potable water: The role of hydrodynamic cavitation.” Water Supply, 13(2), 219–229.
Caron, E., Chevrefils, G., Jr., Barbeau, B., Payment, P., and Prevost, M. (2007). “Impact of microparticles on UV disinfection of indigenous aerobic spores.” Water Res., 41(19), 4546–4556.
Emerick, R. W., Loge, F. J., Ginn, T., and Darby, J. L. (2000). “Modeling the inactivation of coliform bacteria associated with particles.” Water Environ. Res., 72, 432–438.
Emerick, R. W., Loge, F. J., Thompson, D., and Darby, J. L. (1999). “Factors influencing ultraviolet disinfection performance—Part II: Association of coliform bacteria with wastewater particles.” Water Environ. Res., 71, 1178–1187.
Gehr, R. (2005). “Collimated beam tests: Their limitations for assessing wastewater disinfection by UV and a proposal for an additional evaluation parameter.” Proc. 3rd Int. Congress on Ultraviolet Technologies, IUVA, Whistler, British Columbia.
Gogate, P. R. (2002). “Cavitation: An auxiliary technique in wastewater treatment schemes.” Adv. Environ. Res., 6, 335–358.
Gogate, P. R., and Pandit, A. B. (2000). “Engineering design methods for cavitation reactors II: Hydrodynamic cavitation reactors.” AIChE J., 46, 1641.
Henglein, A. (1995). “Chemical effects of continuous and pulsed ultrasound in aqueous solutions.” Ultrason. Sonochem., 2, S115.
Kalumuck, K. M. and Chahine, G. L., (2000). “The use of cavitating jets to oxidize organic compounds in water.” J. Fluids Eng., 122, 465–470.
Keill, F. J., and Swamy, K. M. (1999). “Reactors for sonochemical engineering present status.” Rev. Chem. Eng., 15, 85.
Lindley, J., and Mason, T. J. (1987). “Use of ultrasound in chemical synthesis.” Chem. Soc. Rev., 16, 275.
Liu, G. (2005). “An investigation of UV disinfection performance under the influence of turbidity and particulates for drinking water applications.” MA thesis, Dept. of Civil Engineering, University of Waterloo, Waterloo, Ont.
Loge, F. J., Emerick, R. W., Health, M., Jacangelo, J., Tchobanoglous, G., and Darby, J. L. (1996). “Ultraviolet disinfection of secondary effluents: Prediction of performance and design.” Water Environ. Res., 68, 900–916.
Loge, F. J., Emerick, R. W., Thompson, D. E., and Darby, J. L. (1999). “Factors influencing UV disinfection performance—Part I: Light penetration into wastewater particles.” Water Environ. Res., 71, 377–381.
Mamane, H., and Linden, K. G. (2006). “Impact of particle aggregated microbes on UV disinfection. I: Evaluation of spore-clay aggregates and suspended spores.” J. Environ. Eng., 132(6), 596–606.
Mason, T. J. (1986). “Use of ultrasound in chemical synthesis.” Ultrasonics, 24, 245.
Mason, T. J. (1999). “Sonochemistry: Current uses and future prospects in the chemical and processing industries.” Philos. Trans. R. Soc. London, 357, 355.
Moholkar, V. S., and Pandit, A. B. (1996). “Harness cavitation to improve processing.” Chem. Eng. Prog., 92, 57–68.
Moholkar, V. S., Senthilkumar, P., and Pandit, A. B. (1999). “Hydrodynamic cavitation for sonochemical effects.” Ultrason. Sonochem., 6, 53.
Parker, J. A., and Darby, J. L. (1995). “Particle-associated coliform in secondary effluents: Shielding from ultraviolet light disinfection.” Water Environ. Res., 67, 1065–1075.
Qualls, R. G., Ossoff, S. F., Chang, J. C. M., Dorfman, M. H., Dumais, C. M., Lobe, D. C., and Johnson, J. D., (1985). “Factors controlling sensitivity in ultraviolet disinfection of secondary effluents.” J. Water Pollut. Control Fed., 57, 1006–1011.
Scheible, O. K., and Bassell, C. D. (1981). “Ultraviolet disinfection in a secondary wastewater treatment plant effluent.” Rep. No. EPA-600/S2-81-152, U.S. Environmental Protection Agency, Cincinati.
Senthilkumar, P. (1997). “Studies in cavitation: Modelling and scaleup of cavitational reactors.” Master’s thesis, University of Mumbai, Mumbai, India.
Shah, Y. T., Pandit, A. B., and Moholkar, V. S. (1999). Cavitation reaction engineering, Plenum, New York.
Suslick, K. S., Didenko, Y., Fang, M. M., Hyeon, T., Kolbeck, K. J., McNamara, W. B., III, Mdleleni, M. M., and Wong, M. (1999). “Acoustic cavitation and its chemical consequences.” Philos. Trans. R. Soc. London, 357, 335.
Thompson, L. H., and Doraiswamy, L. K. (1999). “Sonochemistry: Science and engineering.” Ind. Eng. Chem. Res., 38, 1215.
Von Sonntag, C., Mark, G., Tauber, A., and Schuchmann, H. P. (1999). “OH radicle formation and dosimetry in the sonolysis of aqueous solutions.” Adv. in Sonochem., T. J. Mason, ed., 5, 109.
Ward, R. W., and DeGrave, G. M. (1978). “Residual toxicity of several disinfectants in domestic wastewater.” J. Water Pollut. Control Fed., 50, 46–60.
Whitby, G. E., and Scheible, O. K. (2004). “The history of UV and wastewater.” IUVA News, 6(3), 15–26.
Winward, G. P., Avery, L. M., Stephenson, T., and Jefferson, B. (2008). “Ultraviolet (UV) disinfection of grey water: Particle size effects.” Environ. Technol., 29(2), 235–244.
Information & Authors
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Published In
Journal of Environmental Engineering
Volume 135 • Issue 10 • October 2009
Pages: 936 - 943
Copyright
© 2009 ASCE.
History
Received: Jul 25, 2008
Accepted: Feb 25, 2009
Published online: Sep 15, 2009
Published in print: Oct 2009
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