Ultrasonically assisted dewatering of waste activated sludge

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The disposal of waste activated sludge (WAS) is difficult for many wastewater treatment plants. It contains large quantities of water which is difficult to be removed. In this study ultrasonically assisted dewatering of WAS from pulp and paper mill has been studied. Ultrasound could improve the laboratory scale dewatering of WAS. Wet mass of fresh sludge could be decreased tens of percentages and dry solids content (DS) increased 2 %-units when using a short ultrasonic pre-treatment. Ultrasound seemed to disintegrate especially large and fragile protozoa cells, which contained a lot of bound water. Released water could be removed and DS increased both at batch centrifugation and at continuous belt filter pressing. The benefit from released water for dewatering was lost with too violent ultrasonic treatment because some of the dewatering properties of sludge worsened during ultrasonic treatment. There is a good potential to improve dewatering of WAS with ultrasound but both technically and economically it is better to fractionate the part of the sludge for ultrasonic treatment which will easily be disintegrated and has positive effect on dewatering.
Original languageEnglish
Title of host publicationProceedings
Subtitle of host publication19th International Congress on Acoustics, ICA 2007
Publication statusPublished - 2007
MoE publication typeA4 Article in a conference publication
Event19th International Congress on Acoustics, ICA 2007 - Madrid, Spain
Duration: 2 Sep 20077 Sep 2007


Conference19th International Congress on Acoustics, ICA 2007
Abbreviated titleICA 2007

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    Kyllönen, H., Pirkonen, P., & Grönroos, A. (2007). Ultrasonically assisted dewatering of waste activated sludge. In Proceedings: 19th International Congress on Acoustics, ICA 2007 (Vol. 10, pp. 6410-6414) http://www.sea-acustica.es/WEB_ICA_07/fchrs/papers/ult-11-006.pdf