Getting the measure of biosolids stockpile emissions

Posted 4 December 2017

Emissions
Lowering emissions in the water industry will require a much better understanding of greenhouse gas production during biosolids treatment processes, according to a PhD candidate, whose world-leading research quantifies greenhouse gases from stockpiling.  

University of South Australia PhD candidate Norman Goh said quantifying emissions from biosolids stockpiles has long been mismeasured. 

“Before you can reduce your greenhouse gas emissions, you need to know what your emissions are,” Goh said. 

“And there has been a clear gap in our understanding of biosolids stockpile emissions – we don't have a good grasp of stockpile emissions and have been sort of guessing about the measurements.

“Historically, we have adapted a section in the guidelines that applies to landfill to try to quantify these greenhouse gas emissions. However, stockpiles are quite distinct to landfills, and recent research has revealed that applying adapted landfill models is not the best approach because you are not quantifying the right gases.”

While drafting his PhD research on biosolids and soil carbon sequestration, Goh decided to do further research into biosolids stockpile emissions to see if he could find a better way of quantifying emissions from wastewater treatment processes. 

“I wanted to look at how we measured the emissions coming off biosolids stockpiles and compare it to current methods and see if we can do better,” he said.

“Similar work has been done in Victoria, but that is the only instance worldwide of such a study. I wanted to have a look at what we are doing here in South Australia and see if it compares.”

Goh said the results from his study show that we currently overestimate methane emissions by at least five times the measured amount. 

Additionally, nitrous oxide is not being accounted for but comprises at least 92 per cent of all methane and nitrous oxide emissions.

Goh’s work is part of a more concerted effort industry-wide to better understand treatment process emissions, which he said will be much needed as laws evolve and change to better manage greenhouse gas emissions in the future. 

“The overarching goal of research like this is about being proactive and looking at understanding our processes in order to better quantify them,” he said. 

“If we understand our processes properly, we will be in a better position to mitigate and reduce the associated emissions. 

“We want to be on the front foot, as a nation-wide water industry, and be able to produce effective strategies to reduce our carbon footprint.”

This research was supported by the CRC for Low Carbon Living Ltd. (project RP2008) whose activities are supported by the Cooperative Research Centres program, an Australian Government initiative. 

For further information on this research, please contact Dr Michael Short, Michael.Short@unisa.edu.au or Professor Chris Saint at Christopher.Saint@unisa.edu.au.


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