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Cells grow on one side of the membrane in direct contact with air, and are fed through the extremely porous membrane

Bits & pieces

Most new antibiotics can't be made efficiently in liquid culture because the cells need to grow at the interface between the air and a solid. The NMB provides the cells with a solid support (membrane) in direct contact with the air, but it also has a liquid stream on the other side of the membrane, so the antibiotic produced can be easily separated, and the culture conditions easily controlled

The system is so simple it can also be used in homes to recycle grey water from hand basins and showers for use in washing machines, toilets and the garden. This could reduce household water consumption by 60 per cent

At low temperatures Tony's system smells like a pond or stream and at high temperatures smells like vanilla.

Poo! Clean enough to drink

Imagine a technology that can cheaply make sewage and waste water clean enough to drink, as well as efficiently produce the next generation of super-bug busting antibiotics and food for aquaculture farms all at the same time.

Well, look no further. A scientist from the Australian Nuclear Science and Technology Organisation (ANSTO) has invented a membrane bioreactor technology that can do all this, and more.

Dr Tony Taylor described his revolutionary membrane as a simple arrangement of gills that uses bacteria to operate as a lung and stomach. "It literally eats poo and breathes air," he said.

"This invention is called a nano-particulate membrane bioreactor (NMB) which is ideal and cost effective for recycling sewage and grey (washing machine) water. The system is so versatile it can be built in a variety of sizes for use in individual houses, unit complexes or municipal sewage treatment plants.

"ANSTO is currently seeking business partners to help develop and manufacture these systems," he said.

The invention contains a biomass, which is essentially a bunch of cells made up of fungi and bacteria, which eat solid material. But to get busy breaking down the bad stuff in waste water, getting oxygen is a big deal. In most current systems cells are grown in liquid, which means oxygen levels are low and aeration is expensive.


	Tony in the lab. His technology has applications for water treatment, aquaculture and antibiotic production

Tony's invention is different because it involves a simple cheap porous membrane, which is being patented by ANSTO.

"Cells are grown on one side of the membrane in direct contact with air, enabling 50 times as much biomass (cells) to grow on the membranes, compared to other such membrane-surface culture technologies," he said. On the other side, a liquid nutrient stream (sewage and waste water) feeds the cells through the extremely porous membrane.

"At about $1 per square metre, our technology is cheaper than current membranes which can cost up to $500 per square metre," Tony explained.

The bioreactor also has cheaper running costs. Many sewage plants spend around $250 000 a year on electricity to provide aeration to their systems. The NMB should cost only 20% of this. Because aeration is passive, the air simply passes between the gills.

To give you an idea of the compact size of this invention, imagine a fridge with a freezer section at the bottom. In Tony's system, the waste water flows vertically over the membranes in the top tank where ammonia oxidation occurs. Suspended solids and cells are also trapped in a biofilm (slime layer) on the membranes, which later falls off and is trapped under plates in the bottom tank, where anaerobic respiration occurs to produce nitrogen gas.

The captured sludge can either go back into the sewage system or be used for other purposes like aquaculture.

"The best feature of this system is that aeration is passive and free, reducing the cost of secondary and some of tertiary treatment for a kilolitre of water from $1.00 to 20c, which has resulted in strong industry support."

So how does Tony feel about his discovery?

"Well, some people choose to work with sewage, others have sewage thrust upon them," he quipped. "No seriously, I am very excited about the project because it has so much potential."

One potential area is aquaculture. This is the art of farming aquatic animals for food. "The sludge can be used to feed prawns and yabbies. The NMB system delivers so much oxygen to the water that higher organisms (worms and insects) appear in the sludge in 24 hours. These make ideal fish food!

"I believe sewage treatment plants with aquaculture farms downstream could be transformed from costing $5 million a year run, to making $40 million," Tony stated.

Before you start getting worried about seafood fed with poo, be aware that two-thirds of the prawns we eat grew plump eating the stuff. These 'cockroaches of the sea' are detritovores, so poo and rotting things are staples in their diet!

Tony's invention is a true platform technology, having applications across many industries. For example, membrane has potential life saving applications for developing new antibiotics.

The development of the bioreactor has gone through four stages and continues to be refined. Tony, who has literally been 'up to his neck in it', has worked with a number of sewage sources, one being ANSTO's waste.

Being quite a character, Tony concluded by saying, "I would lastly like to thank all ANSTO staff for their contributions."