Basic Study on Sludge Concentration and Dehydration with Ultrasonic Exposure

Abstract

We study the condensation of sludge and the improvement of the dehydration efficiency of sludge by acoustic cavitation for efficiency improvement and cost reduction in water treatment. An ultrasound wave was irradiated into activated sludge in the water tank of our ultrasound exposure system and a standing wave acoustic field was formed using a vibrating disk driven by a Langevin-type transducer. The vibrating disk was mounted on the bottom of the water tank. Acoustic cavitation was generated in the activated sludge suspension and the sludge was floated to the water surface by ultrasound exposure with this system. We observed B-mode ultrasound images of the activated sludge suspension before ultrasound exposure and that of the floated sludge and treated water after ultrasound exposure. The ultrasound diagnostic equipment was used for the observation of the B-mode ultrasound images of the sludge. It was found that the sludge floated to the water surface because of adhesion of microbubbles generated by acoustic cavitation to the sludge particles, which decreased the sludge density. It can be expected that the drifting sludge in water can be recovered by the flotation thickening method of sludge as an application of the results of this study. It is difficult to recover the drifting sludge in water by the conventional gravity thickening method.

Activated Sludge Growth under LED Illumination

“…It is a great problem in both economical and environmental aspects. Several processes are carried out in several countries to reduce excess sludge in water treatment [1][2][3][4][5][6]. The sludge growth is also a focus of interest among the scientists and several reports are available to observe the activated sludge growth [7,8].…”

Development of Rotary Magnetoferrite Treatment with Stirrers for Waste Water Treatment Plants to Reduce Excess Sludge

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