Chemical engineers are working to keep groundwater treatment aerator operators safe by pinpointing factors that could increase the risk of Legionnaires’ disease.
Legionnaires’ disease is a respiratory illness spread by inhaling water droplets containing bacteria that flourish in warm, moist conditions, such as those found in air conditioner cooling towers.
While people who inhale the bacteria don’t always get sick, some will develop pneumonia-like symptoms. Smokers, older people, and those with weakened immune systems or existing respiratory conditions are at greater risk.
Aeration systems in groundwater treatment plants used in regional Australia can also provide ideal conditions for the bacteria to grow. Because operators are exposed to airborne mists from water being sprayed onto plates, this puts them at risk of contracting the disease.
Associate Professor Pierre Le Clech is leading a team of chemical engineering researchers at the University of New South Wales (UNSW) who are working on a system to keep these workers safe.
Le Clech is working to improve the design of aeration units as well as developing a risk management tool that “connects the dots” between factors that could increase the risk to operators.
“The way the current design and configuration of those devices has been done hasn’t taken into account that risk,” he told create.
Le Clech added that the risk of bacteria being transferred from aerator systems to drinking water is “almost nil”, as they would be killed by the chlorination process that follows.
The researchers are collaborating with Water Corporation in Western Australia to make tools and guidelines available to the national and international water treatment industry.
Prevention is better than cure
While outbreaks of Legionnaires disease caused by water cooling towers are reported on a regular basis, Le Clech explained there have not yet been any instances of groundwater aerator operators contracting the illness.
“It’s a proactive action from Water Corp to address that risk before it becomes a real problem,” Le Clech added.
One of the main pathogens responsible for Legionnaires’ disease is Legionella pneumophila. While Legionella cannot be directly detected through sensors, Le Clech’s goal is to monitor and record parameters that could indicate any risk of the pathogen being present.
These parameters include the mode of operation and material used to construct the aerator, groundwater quality and environmental conditions such as weather. Temperature is also an important consideration – Legionella thrives in temperatures between 37ºC and 43ºC.
“There are some very advanced tools being studied, and hopefully it will result in a very practical and useful outcome for the industry,” he said.
Le Clech’s team is also investigating substances that could point to the presence of Legionella.
“It could be certain proteins [or] certain organic material that could be more easily detected online. And if we see their concentration increasing significantly, it is one potential indication that Legionella is growing and could be an issue,” he said, adding that maintaining, cleaning or changing the operating mode of equipment could reduce the risk in those instances.
If a reliable indicator is identified, the researchers hope to develop an economically viable online sensor that can be installed in small groundwater treatment plants. The sensors could also be modified for other applications, including detecting indicators of blue-green algal blooms.
Practical outcomes
Over the next two years, the researchers will provide Water Corp with a set of guidelines that will help them design, clean and maintain a new generation of aerators to reduce the risk of Legionella.
Le Clech explained that the Australian and New Zealand guidelines for water and air handling systems currently used for aerators and public air conditioning systems do not provide enough guidance on what needs to be done.
“We are reviewing and trying to assess the gaps in those existing guidelines,” Le Clech said, adding that his team would develop a set of complementary guidelines to fill those gaps.
As well as being used in Western Australia, Le Clech hopes the guidelines will be shared by other water utilities, particularly in the Northern Territory.
There is also potential to boost the level of understanding of how best to reduce the risk of Legionella in countries including Indonesia, where similar groundwater aerators are widely used.
Le Clech emphasised the study was not about “breathtaking findings”, but connecting the dots to reduce the risk of Legionnaires’ disease.
“It’s not blue sky research, where we hope that if we have the right mix something great will happen. We’re just trying to improve what is done,” he said, adding that it was exciting to be working with industry to address this important problem.