Apr 2 2019
Scientists at RMIT University showed how the flow behavior of sludge can be used as a tool to measure how rapidly organic matter is dissolving at high temperatures, making the way for online tracking of process performance.
Traditional approaches to evaluating the performance of thermal treatment necessitate laborious sampling and chemical analysis. But rheology calculations—which compute and detail how liquids flow—can be performed online in real time.
The study discovered a correlation between how sludge dissolves and transforms in its flow behavior, signifying it may be possible to track thermal treatment performance just by monitoring the flow.
Chief investigator Associate Professor Nicky Eshtiaghi, from the School of Engineering, said appropriately estimating the rheological parameters of sludge is crucial to proficient process design.
“Our technique enables engineers and plant operators to conveniently obtain these parameters without having to perform the measurements at high temperatures themselves,” Eshtiaghi said.
The team hopes the research motivates deeper consideration of flow behavior in improving and engineering high temperature and high pressure sludge-handling processes. The equations in the research are founded on direct measurement of sludge at settings that imitate real-world thermal treatment processes. The new method can measure flow behavior without damaging the samples, frequently a huge challenge during data collection of concentrated sludge.
Thicker sludge, more biogas
The research also revealed that changing the thickness of sludge has little influence on the efficacy of thermal treatment. This means plant operators could boost biogas production downstream, by increasing the solid content of sludge during preliminary treatment processes.
Thicker sludge can be beneficial for both optimising efficiency overall and for producing more biogas. With our discovery that the thickness of sludge makes no difference, this research gives plant operators more flexibility in designing processes that can better exploit the renewable energy potential of wastewater sludge treatment.
Nicky Eshtiaghi, Chief investigator Associate Professor, School of Engineering, RMIT University.
Eshtiaghi, a member of the Water: Effective Technologies and Tools (WETT) Research Centre at RMIT said the study could enable more resourceful design and trouble-shooting of mixers, pumps, and heat exchangers in the sludge treatment process.
The research paper, with lead author and PhD researcher Kevin Hii, has been published in Water Research (DOI: 10.1016/j.watres.2019.03.039).