The effect of high powered ultrasonic treatment on an Australian anaerobic digester

Wellings, Mansell (2017) The effect of high powered ultrasonic treatment on an Australian anaerobic digester. [USQ Project]


Anaerobic digesters are used to treat sludge which is the natural forming by-product of waste water treatment. The sludge needs to be stabilised due to health and cost reasons before it can be disposed of. While anaerobic digesters are designed to have working lives of 25 years or more, they are often found working outside of their original design parameters. This is usually due to an increase in hydraulic loading brought on by unforeseen surges in population growth.

As a result, engineers constrained by capital spending budgets, must find innovative ways to increase the capacity of the digesters without going to the expense of building another anaerobic digestion tank.

Pre-treatment of the sludge has shown to be effective in increasing volatile solids destruction (VSD). This means the process can be sped up without a decrease in digester performance. The Ultrawaves® technology is a pre-treatment that uses high powered ultrasound (HPUS) to break apart sludge flock and generate cell lysis, the combination of which has been shown to improve anaerobic digestion of the sludge.

While there is adequate data to support the validity of the technology in overseas reference plants, it has not yet been proven viable under Australian conditions. This research aims to examine the effect of ultrasonic treatment running in a side stream configuration on a full-scale anaerobic digester situated in Maroochydore Waste Water Treatment Plant on the Sunshine Coast.

Unfortunately, there was no discernible increase in performance to the anaerobic digester. This was due to instabilities in other parts of the sludge handling process which were not related to the operation of the ultrasonic reactor. Time limitations also meant that even if the problems were rectified, there was not enough data to provide a definitive result. Also limitations in measurement equipment and laboratory testing made assessing the performance of the anaerobic digester more difficult than normal. As a result, assumptions about the process had to be made, which may have decreased the accuracy of the results.

To achieve a better outcome in the future, process stability needs be increased, measurements made in the sludge handling process need to be simplified, and the frequency in laboratory testing should also be increased.

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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Engineering (Honours) (Instrumentation and Control)
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: McCabe, Bernadette
Date Deposited: 06 Sep 2022 23:13
Last Modified: 06 Sep 2022 23:13
Uncontrolled Keywords: Anaerobic digesters; sludge; waste water treatment; ultrasonic treatment

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