October 18, 2010
The Wall Street Journal
High-Tech Cures for Water Shortages
Software that can spot leaks, improved recycling—and other innovations to keep things flowing
Can technology solve the worlds' water woes?
Growing populations are straining supplies in parched areas of the U.S. Southwest, the Middle East and Australia, forcing governments to come up with costly solutions or face the risk of shortages. Other regions have plenty of water but lose billions of gallons a day because of an aging infrastructure prone to leaks and catastrophic failure.
While there's no single miracle cure for water shortages, a host of innovative technologies already are making headway, or promise to do so in the near future. Sophisticated software can quickly spot leaky pipes, for instance, while new filters can more efficiently draw fresh water from the sea or clean wastewater, using everything from microscopic tubes to proteins found in living cells.
Here's a look at some of the ideas that are being adopted or are on the horizon.
Cities in the developed world have been delivering clean, safe water for more than a century. And that's the problem: The infrastructure is old—in many cases, past the end of its useful life. A 2009 report found that U.S. water systems lose seven billion gallons of treated drinking water every day, enough to meet the average daily needs of 20 million households.
Stopping these leaks first means finding them. Utilities have monitoring systems, but the data must be downloaded from sensors that listen for leaks in the field and then analyzed. One way to simplify the job: sensors and software that analyze acoustic signals to more accurately locate leaks. These sensors don't monitor the pipes constantly, but they let utilities conduct regular surveys to look for problems.
One company, Echologics Engineering Inc., based in Toronto, uses sensors that are placed on water hydrants or other above-ground fixtures and can determine within a few inches the location of a leak between the sensors; they can also recognize leaks that occur outside the length of pipe being tested.
Another solution, software from Israel-based TaKaDu, analyzes data from a utility's existing industrial-control systems, using sophisticated algorithms and statistical models to spot anomalies. Although the software can't pinpoint the location of a leak, it can narrow it down to a few blocks.
To reduce time-consuming and disruptive repairs, new technologies make it possible to fix pipes with a minimum of digging. One uses a flexible liner to fill a section of pipe; steam or hot water is then pumped into the liner, causing it to harden and seal any leaks. Insituform Technologies Inc. of St. Louis has a felt-and-fiberglass liner that can withstand the high pressures inside water pipes.
For most people in the developed world, there's one grade of water that's good for drinking, cooking, watering the lawn and flushing the toilet. That's expensive, wasteful—and unnecessary.
One answer: Use recycling to expand the supply of water. Rather than dumping treated wastewater into rivers or the ocean, it can be cleaned further for irrigation, industrial or other nonpotable uses, or to be returned to aquifers.
A 250-unit apartment building in New York uses a technology known as a membrane bioreactor, or MBR, from General Electric Co. to process and recycle its wastewater. An MBR combines an ultrafiltration membrane with a system where micro-organisms break down waste. The building recycles the treated wastewater (which is further disinfected with ultraviolet light) to flush toilets, irrigate landscaping and fill the cooling towers for its air-conditioning system. This reduces the building's freshwater draw from the city by more than 75%.
Most of these methods rely on established treatment techniques. But a growing concern over a host of other trace chemicals in wastewater has spurred interest in new technologies. Advanced oxidation, a technique used in industrial water recycling that breaks down trace chemicals using a compound of hydrogen and oxygen, is getting increased attention for municipal reuse. APTwater Inc., a start-up in Pleasant Hill, Calif., is bidding to provide the technology to the city of Anaheim for a demonstration project that would use recycled water for toilet flushing and landscape irrigation in the City Hall complex.
In many places, getting more use out of existing supplies isn't enough—more water is needed to meet the needs of a growing population. In those cases, desalination looks attractive.
After all, 97% of the world's water is found in oceans but is undrinkable because of its high salt content. Increasingly, communities are turning to desalination to tap that resource.
Most older plants use distillation to separate salt from water. But the process—which basically requires boiling huge volumes of water—carries a high price tag and uses lots of energy. The most common alternative, reverse osmosis, is cheaper, but it's still pricey and energy-intensive. So, researchers are looking to improve the process.
Reverse osmosis uses extremely high pressure to force water through a semipermeable membrane and separate out salts. One technique, developed by NanoH2O Inc., of El Segundo, Calif., adds a thin layer of nanoparticles to a polymer-based membrane. The nanomaterials attract water and reject salts and other particles that can clog other membranes, reducing the energy needed to push water through the membrane.
Another nanotechnology, carbon nanotubes, can be used to make membranes that separate salt and other contaminants. Though the membranes are still in a very early stage of development, developers say they could cut the cost of reverse-osmosis desalination by 25%. Meanwhile, a pair of Danish companies, Aquaporin A/S and AquaZ A/S, are working to develop commercial membranes using aquaporins—proteins that move water in living cells and along the way efficiently separate H2O from other molecules.
Finally, there's an option that turns reverse osmosis on its head: It uses natural "forward," or direct, osmosis to draw fresh water from seawater. Using a membrane, seawater is separated from a liquid with even higher saline concentrations; natural osmotic pressure pulls H2O from the seawater into a solution of ammonia salts, which can be evaporated at a relatively low temperature. Oasys Water Inc. in Cambridge, Mass., expects to have a pilot-scale plant to test the technology by early 2011.