New bioreactors for Tully and Johnstone farms

August 2, 2019

With the help of local landholders, six new denitrification bioreactors will be installed on Wet Tropics farms, in an effort to improve water quality.

Cane and banana farmers are continuing a trend in innovation when it comes to reducing the amount of nitrogen, sediment and pesticides flowing to the Great Barrier Reef, as part of the Wet Tropics Major Integrated Project (MIP), funded through the Queensland Government Reef Water Quality Program.

Farmers involved in the community designed project are trialling the effectiveness of different water quality solutions, most of which are proof-of-concept in the region.

Tully and Johnstone landholders came together to finalise bioreactor designs and construction logistics prior to installation in August.

Bioreactors are woodchip-filled trenches used to remove nitrogen from groundwater before it enters local waterways. To minimise land being taken out of production they can be installed in the bottom of a current drain, or by attaching to ag-pipes, where they intercept water in a paddock before it enters a drain.

Suzette Argent from the MIP said landholders have been integral to the design process.

“We’re lucky to be working with bioreactor experts, but local knowledge is just as critical as technical expertise. You can’t beat the specialist knowledge that farmers have about the landscape, which informs the design process.”

“Ongoing landholder involvement deserves recognition, and we owe last year’s successful installation of a bioreactor, a high efficiency sediment basin and an in-drain wetland to this.”

Suzette Argent placing geotextile over woodchips during a bioreactor installation

“It’s an exciting time because everything we learn here can inform future projects, and potentially be applied in other reef catchments.”

Project staff and landholders monitored treated water from previously installed treatment systems throughout the 2018-19 wet season. It is now being analysed for baseline data as dry season sampling continues. 

As well as the six bioreactors, a second high efficiency sediment basin will be installed. Two wetlands will also be ‘embellished’, which involves enlarging the treatment area of existing sites or improving their hydrology, so that the wetland can process more water.

Professor Steve Turton acknowledged the MIP’s achievements at last week’s Wet Tropics Report Card launch. The Report Card assesses the health of nine river basins from Daintree to the Herbert.

Professor Turton highlighted the collaborative efforts in the MIP. “Genuine partnerships are strengthening the links between science and on-ground practice.”