Abstract
Gravitational thickening is the prevailing method to reduce bio-sludge volume though the process is slow and usually requires addition of polyelectrolyte(s). This paper investigated the potential benefits of sonication on enhancing the bio-sludge gravitational thickening with very low energy dose, thereby called “weak ultrasound”. Results showed that weak sonication significantly changed the bio-sludge settleability and the main mechanism was release of the loosely bound extracellular polymeric substances. The changes were strongly influenced by power density and sonication duration. Low frequency was better but the difference was insignificant. Weak sonication (<680 kJ/kg DS) improved the sludge gravitational thickening while high ultrasonic energy deteriorated the process. Considering both the sludge thickening efficiency and energy consumption, the optimum conditions were 0.15 W/ml, 7 s and 25 kHz. Under such conditions, the energy dose was only 155 kJ/kg DS, much lower than literature reports and the sludge settling time shortened from the original 24 to 12 h. Weak sonication could substitute expensive polyelectrolyte coagulant for bio-sludge thickening. Combination of weak sonication and polyelectrolyte could further reduce the settling time to 6 h. The final water content of the thickened bio-sludge was not changed after sonication or polyelectrolyte addition.
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References
Andrew DE, Mary AH (1998) Standards methods for the examination of water and wastewater, 20th edn. American Public Health Association, Washington DC
Bien J, Wolny L (1997) Changes of some sewage sludge parameters prepared with an ultrasonic field. Water Sci. Tech. 36:101–106
Bougrier C, Albasi C, Delgenes JP, Carrere H (2006) Effect of ultrasonic, thermal and ozone pre-treatments on waste activated sludge solubilisation and anaerobic biodegradability. Chem Eng Process 45:711–718
Chen YG, Yang HZ, Gu GW (2001) Effect of acid and surfactant treatment on activated sludge dewatering and settling. Water Res 35:2615–2620
Chu CP, Chang BV, Liao GS, Jean DS, Lee DJ (2001) Observations on changes in ultrasonically treated waste-activated sludge. Water Res 35:1038–1046
de Sarabia E, Gallego-Juarez JA, Rodriguez-Corral G, Elvira-Segura L, Gonzalez-Gomez I (2000) Application of high-power ultrasound to enhance fluid/solid particle separation processes. Ultrasonics 38:642–646
Dewil R, Baeyens J, Goutvrind R (2006) The use of ultrasonics in the treatment of waste activated sludge. Chin J Chem Eng 14:105–113
Emir E, Erdincler A (2006) The role of compatibility in liquid–solid separation of wastewater sludges. Water Sci. Tech. 53:121–126
Feng X, Deng JC, Lei HY, Bai T, Fan QJ, Li ZX (2009) Dewaterability of waste activated sludge with ultrasound conditioning. Bioresour Tech 100:1074–1081
Gonze E, Pillot S, Valette E, Gonthier Y, Bernis A (2003) Ultrasonic treatment of an aerobic activated sludge in a batch reactor. Chem Eng Proc 42:965–975
Hua I, Hoffmann MR (1997) Optimization of ultrasonic irradiation as an advanced oxidation technology. Environ Sci Tech 31:2237–2243
January B, Lidia W (1997) Changes of some sewage sludge parameters prepared with an ultrasonic field. Water Sci Tech 36(11):101–106
Keiding K, Nielsen PH (1997) Desorption of organic macromolecules from activated sludge: effect of ionic composition. Water Res 31:1665–1672
Kim YU, Kim BI (2003) Effect of ultrasound on dewaterability of sewage sludge. Jpn J Appl Phys Part 1 42:5898–5899
Kopp J, Dichtl N (2001) Prediction of full-scale dewatering results by determining the water distribution of sewage sludges. Water Sci Tech 42:141–149
Li H, Jin YY, Mahar RB, Wang ZY, Nie YF (2009) Effects of ultrasonic disintegration on sludge microbial activity and dewaterability. J Hazard Mater 161:1421–1426
Mikkelsen LH (2001) The shear sensitivity of activated sludge: relations to filterability, rheology and surface chemistry. Coll Surface A 182:1–14
Na S, Kim YU, Khim J (2007) Physiochemical properties of digested sewage sludge with ultrasonic treatment. Ultrason Sonochem 14:281–285
Nickel K, Neis U (2007) Ultrasonic disintegration of biosolids for improved biodegradation. Ultrason Sonochem 14:450–455
Schlafer O, Onyeche T, Bormann H, Schroder C, Sievers M (2002) Ultrasound stimulation of micro-organisms for enhanced biodegradation. Ultrasonics 40:25–29
Suslick KS (1990) Sonochemistry. Science 247:1439–1445
Tiehm A, Nickel K, Zellhorn M, Neis U (2001) Ultrasonic waste activated sludge disintegration for improving anaerobic stabilization. Water Res 35:2003–2009
Wang F (2006) Influence of ultrasonic disintegration on sludge characteristics and zero waste activated sludge production process. PhD Dissertation, Tianjin University, China
Wang F, Wang Y, Ji M (2005) Mechanisms and kinetics models for ultrasonic waste activated sludge disintegration. J Hazard Mater 123:145–150
Wang F, Lu S, Ji M (2006) Components of released liquid from ultrasonic waste activated sludge disintegration. Ultrason Sonochem 13:334–338
Yasuhiko W, Kazuhiro T (1999) Innovative sludge handing through pelletization/thickening. Water Res 33(15):3245–3252
Yin X, Han PF, Lu XP, Wang YR (2004) A review on the dewaterability of bio-sludge and ultrasound pretreatment. Ultrason Sonochem 11:337–348
Yin X, Lu XP, Han PF, Wang YR (2006) Ultrasonic treatment on activated sewage sludge from petro-plant for reduction. Ultrasonics 44:E397–E399
Zhang PY, Zhang GM, Wang W (2007) Ultrasonic treatment of biological sludge: floc disintegration, cell lysis and inactivation. Bioresour Tech 98:207–210
Acknowledgments
The authors thank financial supports from Chinese Ministry of Science & Technology (2009ZX07424-005) and the State Key Lab of Urban Water Resource and Environment (QA200903).
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This article has been retracted due to duplicate publication.
The retraction note to this article can be found online at http://dx.doi.org/10.1007/s13762-012-0079-x.
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Zhang, P., Wan, T. & Zhang, G. RETRACTED ARTICLE: Enhancement of bio-sludge gravitational thickening with weak ultrasound. Int. J. Environ. Sci. Technol. 9, 287–296 (2012). https://doi.org/10.1007/s13762-012-0023-0
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DOI: https://doi.org/10.1007/s13762-012-0023-0