Environment

Wastewater that cleans itself results in more water, less sludge

The treatment process in progress, using chemicals naturally abundant in wastewater to clean itself
The treatment process in progress, using chemicals naturally abundant in wastewater to clean itself
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The treatment process in progress, using chemicals naturally abundant in wastewater to clean itself
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The treatment process in progress, using chemicals naturally abundant in wastewater to clean itself
The wastewater sludge that remains after treated water is removed from a hydrotalcite treatment
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The wastewater sludge that remains after treated water is removed from a hydrotalcite treatment

Using wastewater to clean itself is the premise of new Australian technology that relies on the formation of compounds called hydrotalicites, and which results in less sludge than traditional water treatment with lime. In one test, the equivalent of 20 Olympic-sized swimming pools of wastewater were treated, with final sludge reductions of up to 90 percent.

Hydrotalicites are layered crystal structures of carbonates, magnesium, and aluminum, and importantly, they can trap impurities within themselves.

By chemically manipulating these elements “naturally” present in wastewater in high concentrations, researchers at CSIRO, Australia’s science agency, caused the formation of these hydrotalicites. This process occurs as the concentration of magnesium and aluminum is altered and the pH of the water raised. As the crystals form, trapped within them are numerous other waste substances – in the test case, those included radium, rare earth elements, anions and transition metals.

The resulting mixture can be easily centrifuged to separate out the sludge, which there is less of due to its higher concentration and smaller volume of water mixed in. The now-concentrated sludge can be theoretically "mined" again to recover some of the metals and minerals from the mixture. The water can be more efficiently purified further, if needed, and reused by the facility.

The wastewater sludge that remains after treated water is removed from a hydrotalcite treatment
The wastewater sludge that remains after treated water is removed from a hydrotalcite treatment

With the reduction in volume of sludge comes greater ease and lower costs in transporting and disposing of it.

The process is being developed for licensing by Virtual Curtain Limited.

In the video below, Dr. Grant Douglas, a senior researcher at CSIRO, presents the process and benefits of using wastewater as a template to clean itself.

Source: CSIRO

Turning wastewater into rainwater

4 comments
byrneheart
Another example of the fantastic work that the CSIRO do here in Australia. Unfortunately our prime minister, Tony Abbott wants to to tear the guts out of that fine institution. Science seems to be his enemy.
zekegri
These are great by products and if made into a geo-polymer they could bind the toxic waste into say non-leaching roof shingles.
Ryan Saunders
Now they need to try this out at the Berkeley Pit in Butte Montana.
cmed
Interesting approach. It would be interesting to know how much time is consumed and how many pollutants are removed. The sentence " The water can be more efficiently purified further, if needed, and reused by the facility." gives a hint that the resulting water is of low quality.