Active Research P/L identified a promising combination of ultrasound and fixed film anaerobic digestion technology that would significantly reduce the footprint required to treat sewage and industrial waste streams. Additionally, energy recovered from the waste stream may be sufficient to power the process itself. This project took this technology combination from lab bench to pilot plant scale allowing more accurate assessment of the potential risks and the future viability of this technology in large scale treatment applications.
A mobile pilot plant was constructed and mounted on a semi trailer. This plant included a commercially available sonicator to deliver ultrasound processing and a 3000 litre bioreactor equipped with a fix film anaerobic digester assembly to provide heating and stirring functions. The reactor vessel included ports for sludge sampling and biogas collection.
This mobile pilot plant was easily transportable to various treatment facilities around the Melbourne metropolitan area to collect performance data and experience with a variety of real world effluent streams.
The work at Lilydale Secondary Treatment Plant showed a significant reduction in sludge generation could be achieved, leading to the possibility of size reduction in facilities.
Fixed film technology, as a complimentary component of the digestion process, is viable in the locations trialled.
Ultrasound was found to be a cost effective waste preparation tool which leads to reduced hydraulic retention time and the possibility of smaller footprint processing plants.
Biogas with greater than 70 per cent methane was generated, indicating that self sufficiency in energy requirements can be achieved with careful reactor design.
Additionally, if the value of Renewable Energy Certificates, at the current estimate of $50.00 per MWh, is added to the value of the energy generated, the process would generate a net operating profit.
These results provide a basis for the further development of this viable cost effective technology.