Julho 24, 20190

A southern Tasmanian waste site will soon be turned into wetlands where hazardous leachate will be funnelled into ponds and turned into clean water through a natural process.

Key points:

  • Leachate is like the liquid that runs out of the bottom of garbage bags, but on a bigger scale
  • Some of the waste used in the wetlands project includes disused meth labs, dead animals, diseased oysters, and car bodies
  • Run-off from the waste will be filtered into ponds for treatment where nature turns it into clean water for irrigation

Leachate is best described as the liquid that runs out of the bottom of your garbage bag, but in this case it is on a large scale and not your average household waste.

While the B-Cell at Copping contains household and commercial waste, it has also received disposed meth labs, dead seals and toads, diseased oysters, and waste from planes and ships.

The project follows the success of a wetlands at the Burnie Waste Management Centre, which takes 500 kilolitres of waste water out of the sewerage system every day.


From heavy metals, good things grow

Southern Waste Solutions chief executive Christine Bell said the run-off from the waste cell will be filtered into ponds for treatment.

Ms Bell said the ponds will be lined with gravel and sand and contain native reeds and water plants.

“Nature turns it into clean water, suitable for irrigation,” she said.

“It takes all the heavy metals and salts out of the leachate and uses those things to grow, so it’s beneficial to the plants.”

Ms Bell said once the water was treated it would go back into the leachate system, but could be released into a natural wetlands on site if it meets water quality tests after a trial.


Retro waste goes clean

In what is believed to be an Australian first, the Burnie wetlands has completely eliminated any leachate flow into the sewerage system since the end of 2017.

Burnie City Council engineering services manager Rowan Sharman said the leachate was run-off from capped landfill, made up mostly of household rubbish from the 1980s and 1990s, plus car bodies, steel and concrete.

Until the wetlands, the leachate was going into the sewer network.

“We were looking for opportunities to free up capacity in the town’s waste water treatment plant and manage the discharge in a more environmentally sustainably manner,” he said.

“It’s been a successful treatment process, we haven’t drunk the water but it looks and smells as if it could be consumed.”

The water is further filtered through a ‘wet forest’, which is a swamp made of stringy bark and eucalypts.

More than 70 endemic species are now calling the wetlands home.

Mr Sharman said the water was easily meeting quality measurements set by the Environment Protection Authority.

“It’s been a tremendous success,” he said.

“It takes very, very contaminated water and cleans it up and discharges it into an urban waterway.”

The centre is now exploring ways to discharge leachate from a different landfill site into wetlands.

The site contains waste from 2004 onwards.


Energy from rubbish

Southern Waste Solutions has also trialled renewable energy generation from the waste at its site, which goes back into the TasNetworks power grid.

“Gas contractors LMS periodically come and drill wells into the landfill, like drilling oil wells, and they are all connected up together,” Ms Bell said.

“The gas is used to turn turbines that generate the power.”

Landfill gas is made up of 50 per cent methane, which is a more potent greenhouse gas than carbon dioxide.

The project stops emissions from the decomposing waste being released into the atmosphere.

So far it has been enough to power 1,500 houses a year.

“The amount of gas we’re getting at the moment is a lot better than LMS expected, so they are potentially going to put in another generator within the next year,” Ms Bell said.


[Source: ABC Radio Hobart by Georgie Burgess:]

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