Mattresses floated at local sewage treatment plant

Queensland Urban Utilities has launched a new trial which uses floating wetlands to purify wastewater at the Forest Hill Sewage Treatment Plant, near Laidley. The project involves growing wetlands on specially engineered plastic mattresses, which are then floated on purpose-built lagoons.

Michelle Cull and Mike Oakey from Queensland Urban Utilities.

Queensland Urban Utilities spokesperson Michelle Cull said it was a natural, cost-effective and energy-efficient solution to purifying wastewater.

“The roots of the plants dangle beneath the mattress drawing out nutrients such as carbon, nitrogen and phosphorus,” she said.

“The floating wetland is like nature’s kidney, cleansing the water by trapping sediment and removing toxins.

“It’s a great example of green engineering and also has the potential to reduce operational costs at the plant.”

This is Queensland Urban Utilities’ second trial of the floating wetlands, after a nest of turtles destroyed the pilot program last year.

“Hungry Brisbane short-necked turtles feasted on the roots hanging underwater, killing the plants,” Cull said.

“This time around, we have installed nets and meshing to protect the floating wetland, without removing the turtles from their home.

“So far it seems to be working - the plants are thriving and early water-quality test results are promising.”

The trial will run until the end of the year and, if successful, could be rolled out at similar regional sewage treatment plants.

“Queensland Urban Utilities is committed to finding innovative, natural solutions to wastewater treatment,” Cull said.

“We want to cater for growing populations while not only protecting the environment, but using its natural ability to our advantage.”