The blue-green algae alert at Bray Park Weir has been upgraded to amber.
The blue-green algae alert at Bray Park Weir has been upgraded to amber.

How scientists are filtering out toxic algae in water source

BRAY Park Weir’s blue green algae alert has been upgraded to amber once again with the council adamant Tweed’s treated water is still safe to drink.

Alerts have fluctuated between green and amber at the weir pool since early September when light rain in mid-October partially flushed the weir pool and downgraded the alert.

However the lack of rain since then coupled with hot temperatures algae growth has again been stimulated in the weir pool.

The bulk of Tweed’s water is drawn for treatment from the weir and the Tweed Shire Council has adjusted its water treatment processes at Bray Park Water Treatment Plant to deal with the alert upgrade.

The water is dosed with powder activated carbon and the algae and any potential toxin, together with any taste and odour compounds, binds to the carbon’s surface and is filtered out using membrane ultrafiltration technology.

The blue-green algae alert at Bray Park Weir has been upgraded to amber.
The blue-green algae alert at Bray Park Weir has been upgraded to amber.

Water and wastewater operations manager Brie Jowett said the membrane barrier consists of hollow plastic fibres with billions of microscopic pores thousands of times smaller than a human hair.

“It removes suspended solids, bacteria, particle-bonded viruses and parasites,” she said.

“Our use of PAC also has removed the earthy taste and odour compounds we experienced last week and the Tweed’s drinking water is again tasting and smelling pleasant.”

Two of the council’s three treatment plants at Bray Park and Tyalgum use membrane ultrafiltration technology.

The Uki plant also is capable of removing taste and odour compounds.

The council is routinely monitoring the algae levels in all raw water sources and adjusting its water treatment processes as required.

“While this hot, dry weather continues we can expect to be in this ongoing monitoring and treatment adjustment phase,” she said.

Blue-green algae occur naturally and can reproduce quickly in favourable environmental conditions, such as where there is still or slow-flowing water, abundant sunlight and warm weather as well as sufficient levels of nutrients.

Affected water appears to have a green paint-like scum on the water, near the edges, or greenish clumps throughout the water.



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