Hybrid Advanced Oxidative Pretreatment of Complex Industrial Effluent for Biodegradability Enhancement

The study explores the hybrid combination of Hydrodynamic Cavitation (HC) and Subcritical Wet Air Oxidation-based pretreatment of complex industrial effluent to enhance the biodegradability selectively (without major COD destruction) to facilitate subsequent enhanced downstream processing via anaerobic or aerobic biological treatment. Advanced oxidation based techniques can be less efficient as standalone options and a hybrid approach by combining Hydrodynamic Cavitation (HC), and Wet Air Oxidation (WAO) can lead to a synergistic effect since both the options are based on common free radical mechanism. The HC can be used for initial turbulence and generation of hotspots which can begin the free radical attack and this agitating mixture then can be subjected to less intense WAO since initial heat (to raise the activation energy) can be taken care by HC alone. Lab-scale venturi-based hydrodynamic cavitation and wet air oxidation reactor with biomethanated distillery wastewater (BMDWW) as a model effluent was examined for establishing the proof-of-concept. The results indicated that for a desirable biodegradability index (BOD: COD - BI) enhancement (up to 0.4), the Cavitation (standalone) pretreatment condition was: 5 bar and 88 min reaction time with a COD reduction of 36 % and BI enhancement of up to 0.27 (initial BI - 0.17). The optimum WAO condition (standalone) was: 150oC, 6 bar and 30 minutes with 31% COD reduction and 0.33 BI. The hybrid pretreatment (combined Cavitation + WAO) worked out to be 23.18 min HC (at 5 bar) followed by 30 min WAO at 150oC, 6 bar, at which around 50% COD was retained yielding a BI of 0.55. FTIR & NMR analysis of pretreated effluent indicated dissociation and/or reorientation of complex organic compounds in untreated effluent to simpler organic compounds post-pretreatment.





References:
[1] A. Kumar, Handbook of waste management in sugar mills and distilleries. Somaiya Publication. 2003.
[2] P.C. Sangve, A.B. Pandit, Ultrasound pretreatment for enhanced biodegradability of the distillery wastewater, Ultrason. Sonochem. 11 (2004),pp. 197–203.
[3] D. Pant, A. Adholeya, Biological approaches for treatment of distillery wastewater: a review, Biores. Technol. 98 (2006),pp. 2321-2334.
[4] P.R. Gogate, A.B. Pandit, A review of imperative technologies for wastewater treatment I: Oxidation technologies at ambient conditions. Adv in Envtal Res., 8 (2004), pp.501.
[5] K. V. Padoley, P.D. Tembhekar, T. Sarathchandra, A.B. Pandit, R.A. Pandey, S.N. Mudliar, Wet Air Oxidation as a pretreatment option for selective Biodegradability Enhancement and Biogas generation potential from Complex Wastewater. Bioresource Technol, 120 (2012a), pp. 157-164.
[6] K. V. Padoley, S.N. Mudliar, S.K.Banerjee, S.C.Deshmukh and R.A. Pandey, Fenton oxidation: A pretreatment option for improved biological treatment of pyridine & 3-cyanopyridine-plant wastewater Chem Engg J. 166, 2011.
[7] K. V. Padoley, Virendra Kumar Saharan, S.N.Mudliar, R.A.Pandey, Aniruddha B.Pandit, Cavitationally Induced Biodegradability Enhancement of a Distillery Wastewater, J.Haz. Mat. 219-220, (2012b), pp. 69-74.
[8] H.-L. Wang, W.-Z. Liang, Q. Zhang, W.-F. Jiang, Solar-light-assisted Fenton oxidation of 2,4-dinitrophenol(DNP)using Al 2O3-supported Fe(III)-5- sulfosalicylic acid (ssal) complex as catalyst, Chem. Eng. J. 164 (2010),pp. 115–120.
[9] T.L. Gunale, V.V. Mahajani, Studies in mineralization of aqueous aniline using Fenton and wet oxidaation (FENTWO) as a hybrid process. J Chem Tech Biotechnol. 82, (2007), pp.108-115.
[10] K.-H. Kim, S.-K. Ihm, Heterogeneous catalytic wet air oxidation of refractory organic pollutants in industrial wastewaters: A review, J. Hazard. Mater. 186 (2010),pp. 16-34.
[11] K. Belkacemi, F. Larachi, S. Hamoudi, A. Sayari, Catalytic wet oxidation of high- strength alcohol-distillery liquors, Appl. Catal. A: Gen. 199 (2000),pp. 199–209.
[12] N.S. Daga, C.V.S. Prasad, J.B. Joshi, Kinetics of hydrolysis and wet air oxidation of alcohol distillery waste. Ind Chem Eng. 28, (1986).
[13] H. Debellefontaine, M. Chakchouk, J.N. Foussard, J. N. D. Tissot, P. Striolo, Treatment of organic aqueous wastes: wet air oxidation and wet peroxide oxidation(R). Environ. Pollut. 92, (1996), pp.155–164.
[14] A.G. Chakinala, P.R. Gogate, A.E. Burgess, D.H. Bremner, Treatment of industrial wastewater effluents using hydrodynamic cavitation and the advanced Fenton process, Ultrason. Sonochem. 15 (2008),pp. 49-54.
[15] P.R. Gogate, A.B. Pandit, Hydodynamic cavitation: a state of the art review, Rev. Chem. Engg. 17 (2001) 1-85.
[16] M. Sivakumar, A.B. Pandit, Wastewater treatment: a novel energy efficient hydrodynamic cavitational technique, Ultrason. Sonochem. 9 (2002),pp. 123-131.
[17] APHA, AWWA, WPCF, Standard Methods for the Examination of Water and Wastewater, 20th ed., American Public Health Association, Washington DC, 1998.
[18] Metcalf, I. Eddy, Wastewater Engineering Treatment Disposal Reuse, 2nd ed.,Tata McGraw Hill, New Delhi, 1979
[19] S., Collado, L., Garrido, A., Laca, M., Diaz, Wet oxidation of salicylic acid solutions, Environ. Sci. Technol. 44, (2010), pp.8629-8635.
[20] V.S. Mishra, V.V. Mahajani, J.B. Joshi, Wet air oxidation. Ind. Eng. Chem. Res. 34 (1995), pp.2–48.
[21] S. Mohana, C. Desai, D. Madamwar, Biodegrading and decolorization of anaerobically treated distillery spent wash by a novel bacterial consortium, Biores. Technol. 98 (2007), pp. 333-339.