Low Frequencies Ultrasonic Treatment of Sludge
In the present investigation, ultrasonic (US) irradiation treatment technology has been adopted. The mechanism of action (cavitation and sonochemical reaction) of ultrasonic radiation is such that it acts as a potential tool for enhanced biodegradation and sonodegradation of waste and also recovery of resources from treated waste. In ultrasonic waste treatment technology the frequency of US and treatment time is a significant factor in determining optimal reaction conditions. The optimum frequency is substrate specific and low frequency is suitable for sewage sludge treatment. So we opted low frequency (35 kHz and 130 kHz) ultrasonic treatment over varying intervals of time to find out the possibilities to change the quality of sludge by ultrasonic irradiation. Primary sludge characterization parameters i.e. pH, conductivity, chemical oxygen demand (COD), total solid content, total nitrogen and total phosphorus were measured. Ultrasonic pre-treatment was carried out for 5, 10, 20 and 30 min. each (t1-t4). Under following treatment, temperature rise, increase in the amount of soluble chemical oxygen demand (SCOD), total nitrogen and phosphorus were analyzed. Both control and treated samples (t1-t4) were analysed side by side. Very little change in total nitrogen was observed but significant decline level of phosphorus in samples were seen with increase of time of treatment. These data may provide useful information in the way to solve water and soil pollution by ultrasonic treatment.
Donnelly, K.C. (1989). Mutagenic potential of municipal sewage sludge amended soil. J. Water and Soil Pollution,48: 435-449.
Gronroos, A., Kyllonen, H., Korpijarvi, K., Pirkonen, P., Paavola, T., Jokela, J. and J. Rintala (2005). Ultrasound assisted method to increase soluble chemical oxygen demand (SCOD) of sewage sludge for digestion. Ultrason. Sonochem., 12: 15-20.
Harrison, S.T.L. (1991). Bacterial cell disruption: A key unit operation in the recovery of intracellular products. Biotechnol. Adv., 9: 217-240.
Hua Inez and Michal R. Hoffmann (1997). Optimization of ultrasonic radiation as an advance oxidation process. Environmental Scien. Tech., 31: 2237-2243.
Inca, N.H., Tezcanli, G., Belen, R.K. and I.G. Apikyan (2001). Ultrasound as a catalyser of aqueous reaction system: The state-of-the-art and environmental applications. Applied Catalysis B: Environmental Scien., 29: 167-176.
Jorgensen, P.E., Knudsen, L. and S.E. Jepsen (1999). Sludge Handling-Solution for agricultural use with composting, Conference Material DAKOFA Conference May 1999.
Kjeldahl, J. (1883). A new method for the determination of nitrogen in organic matter. Z. Anal. Chem., 22: 366.
Mason, T. (1991). Practical Sonochemistry: User’s Guide to Applications in Chemistry and Chemical Engineering. Ellis Horword Ltd., Chichester, UK.
Mokrini, A. and S. Esplugas (1997). Oxidation aromatic compounds with UV radiation/Ozone/hydrogen peroxide. Water Sc. Tech., 35(4): 95-102.
Peteier and Francony (1997). Incidence of wave frequency on the reaction rates during ultrasonic wastewater treatment. Water Sc. Tech., 35(4): 175-180.
Tiehm, A., Nickel, K. and U. Neis (2001). Ultrasonic waste activated sludge disintegration for improving anaerobic stabilization. Water Res., 35(8): 2003-2009.
Tiehm, A., Nickel, K. and U. Neis (1997). The use of ultrasound to accelerate the anaerobic digestion of sewage sludge. Water Science Technology, 36(11): 121-128.
Tiehm, A. (1999). Combination of ultrasound and biodegradation: Enhanced bioavailability of polycyclic aromatic hydrocarbons. In: Ultrasound in environmental engineering, TU Hamburg-Harburg Reports on Sanitary Engineering (eds. A. Tiehm and U. Neis), 25: 167-180. GFEU-Verlag (ISBN 3-930400-23-5).
Trivedy, R.K. and P.K. Goel (1984). Chemical and biological methods for water pollution studies. Environmental Publishers, Karad, (ed.) pp. 62-63.
Van Niel, E.W.J., Appeldoorn, K.J., Zehnder, A.J.B. and G.J.J. Kortstee (1998). Inhibition of Anaerobic Phosphate Release by Nitric Oxide in Activated Sludge. Applied and Environmental Microbiology, 64(8): 2925-2930.
Young, F.R. (1989). Cavitation. McGraw-Hill Book Company, Maidenhead, UK, pp. 40-76.