Pictures of the Future        Fall 2008

Hope on Tap

Clean drinking water is a scarce resource worldwide. But modern membrane technology of the type Siemens produces in Australia can help ensure supplies for people everywhere—like the victims of the recent earthquake in southern China.

The people of the southern Chinese city of Jiangyou say that a bowl of water can save a life. The saying was coined by their city’s most famous son, Li Bai, a renowned poet 1,300 years ago. Li is said to have been very drunk when the Chinese emperor unexpectedly appointed him a government official. The emperor expected Li to present him with a couple of new verses to show his appreciation for being so honored. Thinking quickly, the poet poured the contents of the nearest bowl over his face, sobered up, and began composing. Today, every child in China knows what he wrote, which translates as follows: "A waterfall rains down from a thousand meters as if the Milky Way were falling from heaven."

Li Wen also learned this verse when she was a schoolgirl—but the life-saving bowl of water has a completely different meaning for her. That’s because, since May 12, when a powerful earthquake measuring eight on the Richter scale destroyed most of Jiangyou, which is 100 km north of Chengdu, the capital of Sichuan province, she and her family have been living in a refugee camp at the city’s Taibai Square. And the square, located in the center of Jiangyou, happens to be named after the poet Li Bai. "We’ve lost everything, and now we must learn to survive on the bare minimum," says Li. She used to run a kiosk in the city, but at the moment she’s squatting down in front of her tent, cooking a meal of rice with cabbage and garlic. It’s not very filling—but at least it’s healthy and safe, because the water Li is using has been completely purified.

Contaminated water, in fact, is one of the few things earthquake victims in Jiangyou don’t have to worry about these days. Just a few days after the earthquake hit, a "water box," as the refugees call it, was placed in the camp. This narrow cabinet about the height of a grown man is where the camp’s residents get their water for drinking, cooking, and washing. The nondescript unit filters water from the local supply network, whose treatment plants were destroyed in the quake. Several thousand people are now using it to obtain water that is free of bacteria and germs.

Clean Water Wherever It’s Needed. The official name of the water box is "Skyhydrant" and it uses state-of-the-art membrane technology from Siemens of the kind used at the world’s most advanced water treatment plants. "Sky­hydrant enables us to use the best purification procedure that we know of for applications in disaster areas and throughout the Third World," says Rhett Butler, who developed the device (see Interview). "When the images of the earthquake in Sichuan began showing up on TV around the world, Siemens' "Caring Hands" immediately sent 15 Skyhydrants to the region to ensure that victims would at least have access to clean drinking water."

Not much expertise is required to use the devices, which feature instructions posted on a small yellow sticker on the box. "It was very easy to assemble—it took us only ten minutes to unpack one Skyhydrant and put it into opera­tion," says Li Zaoyang, an engineer from Jiangyou’s water authority, which operates the Skyhydrant at Taibai Square.

A hose connects the device to a faucet normally used to water the grass at the square, while a second hose runs from the Sky­hydrant to a small water tank that Li set up on a folding table. There hasn’t been much for him to do since then. Once a day, he moves a small lever on the top of the device’s housing up and down for one minute, opening a valve that lets out water. "That’s how we clean the filter," he explains. Li himself is not very familiar with the exact details of this procedure, but he’s happy not to have to worry about it. After all, like everyone else in Jiangyou, Li has a lot of other things on his mind.

Micrometer Virus Traps. Anyone interested in learning exactly how the water box works would be advised to take a trip to Windsor, Australia, 50 km west of Sydney. There you’ll find a company known as Memcor, a subsidiary of Siemens Water Technologies, that employs 250 people and is the world’s leading developer and manufacturer of water treatment membranes. The company’s reception area contains a Sky­hydrant, but it’s only a demonstra­tion model. "That’s our mini-treat­ment plant," says Memcor Managing Director Bruce Biltoft. "Our normal water treatment facilities are generally a little bigger," he jokes. That’s because Memcor focuses primarily on solutions for municipal treatment plants and major industrial wastewater purification systems.

At the heart of Memcor’s technology is a module that looks like a thick bundle of long spaghetti. Closer examination reveals that it is a series of very thin tubes. In fact, it takes an electron microscope to see that there are tiny perforations in the walls of the tubes. "Those are the membranes," Biltoft explains. "Basically, they function like normal filters. The water molecules move through the holes, and all of the suspended materials in the water are left behind."

And he does mean all of them. With a diameter of only 0.1 µm (0.0001 mm), the pores are so narrow that they can capture even the tiniest particles. It also is impossible for bacteria to get through, and even viruses, which are much smaller, are trapped because they are bonded to other organisms. The only things that can make it through are soluble contaminants, which are removed in water treatment plants using additional process steps.

Water flows through Skyhydrant’s filtration process as it would through a straw. The device’s tubes are over one meter long, yet have a diameter of just 1 mm. Unclean water flows across the outside of the tubes, is forced through the membrane walls, and is then siphoned off on the inside. Major treatment plants have hundreds or even thousands of membrane bundles encased in cylinders, with each bundle containing approximately 10,000 tubes. Here, pumps are used to generate powerful suction, and the water flow direction is briefly reversed several times each hour, before air is forced through the membranes to loosen up and clear away the residues on the outer walls. "All this is done by hand with Skyhydrant," says Biltoft. In fact, the natural pressure of water falling two meters is enough to push water through the membrane, while shaking the bundle at the same time causes the tubes to rub against one another and release dirt. This is exactly what happens when Li Zaoyang jiggles his Skyhydrant’s lever.

Over 800 Patents. As simple as the filtration process is, extensive research and development was needed before it to be used in water treatment plants. It all began in 1984, when scientists at the University of New South Wales in Sydney were working on blood filtering systems for dialysis patients. Several scientists realized that the membranes they were using could also be applied to water treatment technology. After setting up their own company, they began developing membranes that could function reliably for up to ten years and could be produced at a reasonable cost.

"We registered over 800 patents," recalls Biltoft, himself an engineer and one of the company’s pioneers. And the effort paid off. The filtration idea is now a well-established process worldwide. But to get to this point the Australians needed the help of international partners who could provide specific components and expertise. One of those partners was Siemens, whose subsidiary Siemens Water Technologies acquired Memcor in 2004.

Things have been moving in a very positive direction ever since. Every day, a machine spits out dozens of kilometers of membrane fibers. These fibers are glued together into bundles using synthetic resin. The resulting modules are used at facilities around the world. "Demand is increasing rapidly," Biltoft reports. "At the moment, our production volume is growing at a rate of 20 % per year." Memcor’s business volume is thus expanding at a rate twice as high as that of the membrane technology industry as a whole.

"That creates perfect conditions for us to further develop our products," says Biltoft. The plan is to make the membranes even finer, more durable, and less expensive to produce in the future. This will benefit not only Siemens’ major customers but also the people whose welfare is a top priority of the employees in Windsor—people like Li Wen in Jiangyou, who knows better than anyone how a simple bowl of clean water can save a life.
                                                                                                        Bernhard Bartsch