Ultrasonic pre-treatment of biological sludge: consequences for disintegration, anaerobic biodegradability, and filterability
2010
Erden, G. | Filibeli, A.
BACKGROUND: Disintegration was developed as a pretreatment process for sludge to accelerate the digestion processes. Ultrasonic treatment may be a good alternative for sludge disintegration. In this study, different specific energy inputs ranged between 0 and 15 880 kJ kg⁻¹ and very low ultrasonic densities ranged between 0.04 and 0.1 W mL⁻¹ were applied to biological sludge for disintegration purposes. The potential for improving anaerobic digestion through ultrasonic pre-treatment and the effect of ultrasonic pre-treatment on the filterability characteristics of sludge were also investigated.RESULTS: 9690 kJ kg⁻¹ TS of supplied energy and very low power density of 0.09 Wm L⁻¹ are efficient for floc disintegration. For 9690 kJ kg⁻¹ TS, 44% higher methane production was achieved than with raw sludge as a result of biochemical methane potential assay. The supernatant characteristics of the sludge were also affected by the ultrasonic pre-treatment. For 9690 kJ kg⁻¹ TS, the soluble chemical oxygen demand (SCOD), dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) in the sludge supernatant increased by 340%, 860%, 716%, and 207.5%, respectively.CONCLUSION: Ultrasonic pre-treatment is an effective method for biological sludge disintegration even at very low ultrasonic density levels. It leads to increased anaerobic biodegradability but deteriorates the filterability characteristics of biological sludge.
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