Effects of Ultrasonic Treatment on the Waste Activated Sludge

Abstract

Many of the organic compounds make up much of the sludge mass in particulate form and thus require hydrolysis, which is a rather slow process. In order to improve the hydrolysis, some other physical and chemical pretechniques such as thermal hydrolysis, mechanical disintegration, ultrasonic irradiation (ultrasonication), ozone treatment, acidification, and alkaline supplement are applied. Two of these techniques, those are ozone treatment and ultrasonication are generally regarded as environmentally non-hazardous. This preference of ultrasonication is based on the view that this method, as a speed fixing instrument, reduces the time limit of hydrolysis from 20 to 8 days; improves the quality and quantity of the biogas as an end-product; helps microbiological cells break into intracellular entities. The current studies have proved a lengthy ultrasonication period, a low-frequency ultrasonic wave and a high ultrasonic intensity are highly effective for the sludge disintegration. The aim of this work was to review the current studies on the issue mentioned above and presented a brief summary of the results. 

Keywords

• Cavitation
• disintegration
• sludge treatment
• ultrasound
• wastewater treatment

Ultrasonik Arıtmanın Atık Aktif Çamur Üzerine Etkileri

Abstract

Aktif çamur içerisindeki birçok organik bileşik partiküler formda bulunmakta olup, yavaş bir süreç olan hidroliz işlemiyle ayrışmaktadır. Bu süreci hızlandırmak için ısıl hidroliz, mekanik bozunma, ultrasonik radyasyon (ultrasonikasyon), ozonla arıtımı ile ortama ilave asit ve alkali kimyasalların eklenmesi gibi fiziksel ve kimyasal ön işlemler uygulanabilmektedir. Bahsedilen yöntemler içerisinden ozonla arıtım ve ultrasonikasyon işlemleri çevresel açıdan zararsız olmaları dolayısıyla tercih edilmektedir. Bu bakımdan ultrasonikasyon işlemi, gerekli ekipmanın hızlı kurulumu ile hidroliz süresini 20 günden 8 güne kadar indirebilmesi, biyogaz kalite ve miktarını artırıcı etki göstermesi ve mikrobiyal bozunmadaki etkinliği gibi nedenlerden ötürü dikkat çekici bulunmuştur. Günümüzdeki çalışmalar uzun süreli ve düşük frekanslı ultrasonik uygulamaların çamur bozundurmasında oldukça etkili olduğunu göstermektedir. Bu çalışmanın amacı, yukarıda belirtilen konulara ait yapılmış çalışmaları inceleyerek, sonuçlarını özet olarak sunmaktır.  

Keywords

• −Kavitasyon
• bozunma
• çamur arıtımı
• ultrason
• atıksu arıtımı

References

1. Y. Wei, R. Houten, A. Borger, D. Eikelboom, Y. Fan, “Minimization of excess sludge production for biological wastewater treatment”, Water Res., 37, 4453-4467, 2003.
2. A. Tiehm, K. Nickel, M. Zellhorn, U. Neis, “Ultrasonic waste activated
3. stabilization”, Water Res., 35(8), 2003-2009, 2001. for improving
4. anaerobic [3] T. Shimizu, K. Kudo, Y. Nasu, “Anaerobic waste activated sludge digestion-a bioconversion and kinetic model”, Biotechnology and Bioengineering, 41, 1082-1091, 1993.
5. C. Bougrier, C. Albasi, J.P. Delgenes, H. Carrere, “Effect of ultrasonic, thermal and ozone pre-treatments on waste activated sludge solubilisation and anaerobic biodegradability”, Chem. Eng. Process., 45(8), 711-718, 2006.
6. U. Baier, P. Schmidheiny, “Enhanced anaerobic degradation of mechanically disintegrated sludge”, Water Sci. Technol., 36(11), 137-143, 1997.
7. A. Tiehm, K. Nickel, U. Neis, “The use of ultrasound to accelerate the anaerobic digestion of sewage sludge”, Water Sci. Technol., 36(11), 21-128, 1997.
8. M.A. Dytczak, K.L. Londry, H. Siegrist, J.A. Oleszkiewicz, “Ozonation

9. denitrification”, Water Res., 41(3), 543-550, 2007. production and
10. improves [8] S.E. Woodard, R.F. Wukash, “A hydrolysis/thickening/filtration process for the treatment of waste activated sludge”, Water Sci. Technol., 30(3), 29-38, 1994.
11. E. Neyens, J. Baeyens, C. Creemers, “Alkaline thermal sludge hydrolysis”, J. Hazard. Mater., 97(1-3), 295-314, 2003.
12. P. Chu, B. Chang, G. Liao, D. Jean, D. Lee, “Observations on changes in ultrasonically treated waste-activated sludge”, Water Res., 35(4), 1038-1046, 2001.
13. H. Kuttruff, Ultrasonic Fundamentals and Applications, Elsevier Science, Oxford, UK, 1991.
14. A. Tiehm, and U. Neis, Mechanical and radical effects of ultrasound, Environmental Engineering, TU Hamburg-Harburg Reports on Sanitary Engineering, Germany, 1999.
15. E.B. Flint, K.S. Suslick, “The temperature of cavitation” Science, 253(5026), 1397-1399, 1991.
16. P. Riesz, D. Berdahl, L. Christman, “Free radical generation by ultrasound in aqueous and nonaqueous solutions”, Environ. Health Perspect., 64, 233-252, 1985.
17. G. Zhang, I. Hua, “Cavitation chemistry of polychlorinated biphenyls: decomposition mechanisms and rates”, Environ. Sci. Technol., 34, 1529-1534, 2000.
18. F.R. Young, Cavitation, McGraw-Hill Book Company, Maidenhead, UK, 1989.
19. I. Hua, M.R. Hoffmann, “Optimization of ultrasonic irradiation as an advanced oxidation technology”, Environ. Sci. Technol., 31, 2237-2243, 1997.
20. X. Feng, H. Lei, J. Deng, Q. Yu, H. Li, “Physical and chemical characteristics of waste activated sludge treated ultrasonically”, Chem. Eng. Process., 48(4), 187-194, 2009.
21. E. Gonze, S. Pillot, E. Valette, Y. Gonthier, A. Bernis, “Ultrasonic treatment of an aerobic activated sludge in a batch reactor”, Chem. Eng. Process., 42(12), 965-975, 2003.
22. C. Bougrier, H. Carrere, J.P. Delgenes, “Solubilisation of waste-activated sludge by ultrasonic treatment”, Chem. Eng. J., 106(2), 163-169, 2005.
23. P.Y. Zhang, G.M. Zhang, W. Wang, “Ultrasonic treatment of biological sludge: floc disintegration, cell lysis and inactivation”, Bioresource Technol., 98(1), 207-210, 2007.
24. F. Wang, S. Lu, M. Ji, “Components of released liquid from ultrasonic waste activated sludge disintegration”, Ultrason. Sonochem., 13(4), 334-338, 2006.
25. B. Akin, “Waste activated sludge disintegration in an ultrasonic batch reactor”, CLEAN, 36(4), 360-365, 2008.