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Bugs and slime to clean poisoned water

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CRC for Contamination Assessment and Remediation of the Environment

M e d i a R e l e a s e

Bugs and slime to clean poisoned water

September 16, 2013 - for immediate release

Australian scientists have developed a way to clean up the potentially deadly

arsenic that pollutes the drinking water of tens of millions of people around the


A new type of water filter that combines microalgae with bacteria taken from soil

contaminated with heavy metals could prove an effective, cheap and safe way to

rid drinking water of arsenic.

A poster on the technology is being presented by Mr Mezbaul Bahar of the CRC

for Contamination Assessment and Remediation of the Environment (CRC CARE)

at the CleanUp 2013 conference.

“Known as the ‘king of poisons’, arsenic has harmed humans more than any other

toxic chemical in history,” says Mr Bahar, of CRC CARE and the University of

South Australia.

“It contaminates groundwater in more than 70 countries, including Bangladesh,

India, the USA, South America, China, Thailand and Taiwan. Around 137 million

people are poisoned daily by arsenic in their drinking water and food.”

Arsenic poisoning causes vomiting, diarrhoea, and long-term exposure can lead

to cancer, diabetes, heart disease and death. Also, once polluted, the

groundwater is difficult and expensive to clean up.

To help save lives and improve global water security, Mr Bahar and his CRC

CARE research team have developed a technology that uses different types of

tenacious bacteria and microalgae to filter the water.

“Two forms of arsenic are commonly found in the environment: arsenic (III) and

arsenic (V). Arsenic III is 60 times more toxic than the other form and is highly

soluble, which makes it more difficult to remove, as it travels everywhere,” says

Professor Megh Mallavarapu of CRC CARE and UniSA, the principal supervisor

of the research.

“The solution then is to convert arsenic (III) into the less toxic and less soluble

form, making it easier to extract from the water,” Prof. Mallavarapu explains.

“Conventional technologies use chemicals to convert the arsenic, but this is

expensive and often brings unwanted side effects. Scientists have also used

bacteria for this task, but these bacteria require carbon to grow, so it’s

unsustainable unless we keep feeding the bacteria.”

Now, CRC CARE researchers have found kinds of bacteria and microalgae that

can sustain each other. “We found these bacteria in soil that has been

contaminated with heavy metals,” Mr Bahar says. “To survive, the bacteria have

developed special abilities to defeat the toxicity, including converting arsenic into

its less harmful form.”

The next step was to find a way to feed the bacteria continuously - and the

scientists have found certain microalgae that were ideal.

“Microalgae only need sunlight to sustain themselves,” Prof. Mallavarapu says.

“They can generate energy using sunlight, and together with water, they’ll grow

and produce carbon and oxygen to support the bacteria.

“However, when the bacteria break down the organic matter produced by the

microalgae as well as from contaminated water, they produce carbon dioxide,

which in turn can be used to feed the microalgae. So it’s a wonderful partnership.

“Once arsenic (III) is converted to arsenic (V), we can remove it by absorbing it

with a cheap and easily accessible material, such as coir pith made from coconut


Mr Bahar says the bacteria and microalgae can be placed in a bioreactor - a

container that allows them to grow. “We plan to test the technology in the

laboratory and will find out if it can be used in individual households or villages.”

“Arsenic poisoning from natural groundwater is one of the most common and

horrific forms of contamination in the modern world, and the successful

development of a technology with scope to overcome it could well be counted

among Australia’s major humanitarian contributions,” says CRC CARE Managing

Director Professor Ravi Naidu.

“This is a brilliant achievement by Mezbaul and his colleagues - a solution to a

major problem that is simple, elegant, cheap and effective. They are to be

commended for it.”

CleanUp 2013 is hosted by the CRC for Contamination Assessment and

Remediation of the Environment (CRC CARE). It is taking place at the Crown

Conference Centre, Melbourne, Victoria, from 15 to 18 September 2013 and

incorporates the 5th International Contaminated Site Remediation Conference.

Program and details:

Media wishing to attend the conference and interview participants may contact

Adam Barclay on +61 (0)429 779 228 for access to the CleanUp venue.

More information:

Mr Mezbaul Bahar, CRCCARE and UniSA, +61 (0)422 379 429

Prof. Megh Mallavarapu, CRC CARE and UniSA, +61 (0)411 035 757

Prof. Ravi Naidu, Managing Director, CRC CARE, +61(0)407 720 257

Adam Barclay, Communication Manager, CRC CARE, +61 (0)429 779 228