Wastewater testing for coronavirus fragments in NSW is becoming more effective, raising hopes the virus can be contained while the state waits for the rollout of a vaccine.
Sydney Water’s lab team have been able to significantly ramp up the rate of wastewater COVID-19 testing by automating part of the process.
The team that analyses sewage run-off to detect coronavirus fragments on behalf of NSW Health has installed new equipment, allowing them to nearly double the rate of testing from 80 samples a week to almost 150.
“We needed to be able to increase the efficacy of the process,” Sydney Water executive Maryanne Graham said in an interview at the utility’s laboratory in the Sydney suburb of West Ryde.
“Because while we may not have a high level of positive cases in the community (at the moment), we need to continue testing and stay on top of it.”
Testing wastewater for coronavirus fragments has become an essential part of the NSW government’s strategy to fight the community spread of COVID-19.
The idea is that a person who has been infected will shed virus fragments that are going to travel with the flush of a toilet to eventually end up in sewage treatment plants.
By analysing water samples from those plants authorities can detect whether the virus is spreading in a specific area.
On Tuesday, NSW Health announced samples from a waste treatment plant in the Sydney suburb of Liverpool contained virus fragments.
That plant treats wastewater from some 40 suburbs with a population of close to 180,000.
Such information is crucial to encourage targeted virus testing of residents, and with the increased rate of wastewater analysis the hope is the fragments can be detected quicker.
Most days of the week, wastewater samples, chilled on ice and transported in eskis by courier services, arrive at the lab in West Ryde.
There, the murky water goes through a three-step process. The first step is to filter the wastewater, putting it through a membrane that essentially works as a coffee filter. If COVID-19 is present in the wastewater, it will stick to the membrane.
That filter is then put in a vial and sent to a different part of the lab for step two – extracting a molecule called ribonucleic acid (RNA), which the virus uses to encode its genetic information.
That’s done by shredding the filter, adding some chemicals, and grinding it into a smoothie. After separating the liquid from the debris, virus RNA is purified.
Then, finally, the experts analyse that sample to see whether molecular markers of COVID-19 are present.
It’s the second step that’s been automated, leading to a big leap in efficiency.
The virus lab team, around 20 staffers led by technical specialist Sudhi Payyappat, purchased a $50,000 apparatus called a QIAcube that will extract the ribonucleic acid automatically, a process that would previously take hours to do by hand.
“The robotics have been a big step forwards,” said Ms Graham, who is general manager for customer strategy and engagement at Sydney Water.
Another recent development is the ability to test sewage pumping stations, which contain waste from smaller amounts of people. That process will allow Sydney Water’s lab experts to narrow down the results down to specific suburbs.
“Our COVID team is always looking at how they can innovate to improve the process,” Ms Graham said.