Fresh science

Cling wrap that captures CO₂ and a recycling technique for pig waste are two of the research discoveries in this year’s Fresh Science competition. The national competition identifies new and interesting research being done by early-career scientists from around the country and then helps them present their research to the public.

Colin Scholes is one of 16 early-career scientists releasing their research to the public for the first time, thanks to the Fresh Science national program which is sponsored by the federal government. Colin, who is a Melbourne University chemical engineer, has developed a high-tech cling wrap that can ‘sieve out’ carbon dioxide from waste gases.

The plastic membrane filters out carbon dioxide. Photo: CO2 CRC.

The membranes can be fitted to existing chimneys where they capture CO₂ or removal and storage. They are already being tested on brown coal power stations in Victoria’s La Trobe Valley, Colin says.

“The membrane material is specifically designed to separate CO₂ from other molecules,” he says. “It acts like a filter and is much more efficient than existing technology. We are hoping these membranes will become an important part of a carbon capture and storage strategy which will cut emissions from power stations by up to 90%.”

Not only are the new membranes efficient, they are also relatively cheap to produce. “Carbon capture and storage is currently very expensive. Reducing the cost of trapping the CO₂ will make it much more affordable. And cheaper systems mean power generators can put them in place much sooner.”

Another crucial aspect of the membrane has been its toughness - a power station chimney is not a friendly environment. “Trials with real flue gas have been essential for the development of material robust enough to handle industrial conditions,” Colin says.

Colin’s work is supported by the Cooperative Research Centre for Greenhouse Gas Technologies (CO₂ CRC) where he is a research fellow.

Another winner in the program was Andrew Ward, biotechnologist from the South Australian Research and Development Institute (SARDI). Through his clever recycling of pig waste, he has been able to produce feed for aquaculture, water for irrigation, and methane for energy. His ‘waste food chain’ can be applied to breweries, wineries and any system producing organic waste.

He’s done it by taking traditional approaches from China, India and Vietnam, some new ideas and a lot of streamlining and integration to make a system that will meet Australian needs and standards.

His work has been underwritten by the Environmental Biotechnology Cooperative Research Centre (CRC) and pulls together ideas from Murdoch University, SARDI, The University of Adelaide and the CRC.

“We can turn waste into food, save money, save water and improve the environment just by being a bit smarter,” Ward says.

The pig effluent is initially fed into an airtight, two-stage digester. This breaks down the chemical compounds that smell and kills potentially dangerous bacteria, while at the same time producing methane biogas as well as nutrients which can be used to stimulate the growth of tiny seaweeds or microalgae. 

Algae bags (Photo: Andrew Ward).

Ward’s studies showed that the digested piggery effluent is a safe nutrient source for the commercial-scale production of algae which can then be used for aquaculture.

“Once we had the algae growing, we knew we could recreate the ocean food chain from algae to zooplankton to fish,” he says.

Zooplankton bags (Photo: Andrew Ward).

“We use two small native South Australian water fleas, Moina australiensis and Daphnia carinata, which can form the basis of commercial fish meal. By carefully establishing the best conditions for growth and reproduction, the water fleas can be produced more quickly than with existing methods. This makes the system more efficient and the technology financially viable.

What’s more, the zooplankton help to clean up the water in which they grow, by reducing the levels of nutrients and bacteria. They do such a good job that the water can subsequently be used for irrigation.

Ward thinks similar bio-treatment systems can be established to handle the liquid and solid waste from other livestock industries. “This integrated production technique is pioneering work in Australia,” he said. “We hope it will present a shift in thinking for business, where they begin to regard waste no longer as a cost but as an income stream.”

Ultrasound puts the squeeze on mining waste

You may not be able to squeeze blood out of a stone but, by applying the right amount of ultrasound during processing, Jianhua (Jason) Du and colleagues from the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) have been able to squeeze a considerable amount of fresh water from mining waste.

Jason demonstrates the technique at CRC CARE CleanUp 09 conference. (Photo: Meredith Loxton, CRC CARE).

As well as conserving water the technique reduces the waste bulk, which could also save mining companies millions of dollars in operational costs and help postpone significant capital expenditure, Jason says. Jason is another one of 16 winners of the national 2010 Fresh Science program.

“When we looked at one of Rio Tinto's mines in the Murray Darling Basin, we found our method could potentially save 436 megalitres of water a year. That's more than 170 Olympic swimming pools back into the Basin's water reserves - so that's a win for the environment as well as lower costs for the company.”

Between 400 and 600 litres of water are needed to process each tonne of ore. As a result, water makes up between 60 and 95% of the more than 10 billion tonnes of tailings that mineral processing produces each year worldwide.

Some of this liquid is recovered by letting the solids settle in tailings ponds, a process that is aided by the addition of thickeners. But these are low in efficiency. What Jason and his colleagues found is that efficiency can be increased by pumping in the right amount of ultrasonic energy at the right time.

Although in their laboratory-scale trial the technique successfully increased the output of solids only by about 4% by weight, on the scale of a large mine this represents a huge amount of water.

“At one of Rio Tinto's mines outside Australia, we calculated the saving to be about 3.5 gigalitres (or 3500 megalitres) a year, worth more than AU$5.5 million to the company.”

Jason and his colleagues, based at the University of South Australia, used an electron microscope to examine the structure of the solids which formed after flocculants were introduced in the thickener. They found a network similar to honeycomb in which the water was trapped. The ultrasonic energy disrupts this network and leads to a denser aggregation. "It's like shaking up a jar full of flour in a way which causes the flour to compact down," Jason says.

The less water incorporated during processing also means the smaller the landfill site needed for containment. Together with lesser amounts of time and equipment needed to manage the disposal process, this lowers costs even further.

Honeycomb-like structure which retains significant amount of water in tailings before ultrasonic treatment. (Photo: Jason Du)

Ultrasonic vibration collapses the honeycomb structure and releases the trapped water. (Photo: Jason Du)

Jason's work is supported by the Australian Research Council, CRC CARE and Rio Tinto.