By Anne Eisenberg of The New York Times
NO wonder they are called conveniences. Flush toilets swirl human waste down the drain quickly and neatly. But the convenience comes with a rising price for all that follows the flush — a cost that is often paid by municipal water and sewage treatment systems.
Now some groups are rethinking the venerable technology of the flush toilet, particularly for regions that lack such systems or for places where waste water treatment plants, many of them aging, are overburdened by the demands of fast-growing populations.
The Bill and Melinda Gates Foundation has begun a “Reinvent the Toilet” competition and awarded $3 million to researchers at eight universities, challenging them to use recent technology to create models that needn’t be connected to sewers, or to water and electricity lines, and that cost less than pennies per person a day to use. Later prizes will include financing for one or more winning prototypes to be tested and produced commercially.
“The present toilet is a 19th-century device that does not meet the needs of a vast part of the world’s population,” said Frank Rijsberman, an executive at the foundation. Instead, he said, about 2.6 billion people without access to sewer-linked systems must use simple latrines, holes in the ground or just the nearest available spot — a situation that can lead to many health problems, like acute childhood diarrhea.
One of the new toilets being financed by the foundation is a compact chamber that runs on solar power from a roof panel and uses built-in electrochemical technology to process waste.
“We can clean the waste water up to the same level as would come out of a treatment plant,” said Michael R. Hoffmann, a professor of environmental science at the California Institute of Technology in Pasadena, who received $400,000 to develop this solar toilet. It uses the sun’s energy to power an electrode system in the waste water; the electrodes drive a series of cleansing chemical reactions, converting organic waste in the water into carbon dioxide and producing hydrogen that can be stored in a fuel cell for night operation.
The cost of each unit, which can be used up to 500 times a day, may initially be as high as $5,000 for a prototype but would drop with commercial production. Operational costs will be only a few cents a day, Dr. Hoffmann said.
Dr. Rijsberman said chemical engineering might provide the route to inventing many future toilets. Rather than composting waste for six months, as many waterless composting toilets do, the new versions could heat the waste quickly, killing pathogens, he said.
One of the funded projects taking this approach is a design for waste disposal at community bathrooms in South Africa, said Katherine Foxon, a member of the team that is working on the technology. Dr. Foxon is a chemical engineer and senior lecturer at the University of KwaZulu-Natal in Durban. “We’ll process the waste chemically, combusting the feces and using that energy to drive the evaporation of urine,” she said.
Even in countries with extensive sewer systems, researchers are testing toilets that still flush but will divert urine before it gets into the sewer.
“Most nutrients from human metabolism are excreted in urine and must be degraded at treatment plants,” said Tove A. Larsen, a senior scientist at the Swiss Federal Institute of Aquatic Science and Technology, or Eawag, in Dübendorf.
Dealing with urine separately, by siphoning it off to local storage tanks, simplifies waste water management. The urine can then be collected, treated and recycled as fertilizer. Dr. Larsen was a leader of a six-year project at Eawag on urine separation, known as No Mix technology.
The toilets at Eawag’s office buildings are No Mix models. Each has a built-in urinal at the front that drains into storage. The back compartment works like a conventional toilet as waste is flushed into the sewer.
The technology is in its infancy and has drawbacks, Dr. Larsen said. Children have difficulty aiming correctly between the compartments, for instance. And the toilets can cost twice as much as conventional models and require steady maintenance to prevent the build-up of pipe-clogging scale that is deposited by urine.
Dr. Larsen, who is also one of the Gates Foundation winners, will lead an interdisciplinary team in developing a nonflush toilet. It will have separate compartments for urine and feces, she said, along with a third compartment for water that is used to keep the toilet clean. After filtering, this water can be reused in the cleaning process.
Peter P. Rogers, a professor of environmental engineering at Harvard who has long researched water and energy resources, applauded the efforts of the foundation but said the problems that the competition is addressing are monumental.
“You need toilets that are inexpensive and can be used by more than two billion poor people,” he said. There are many potentially good solutions, he said, though, they have not yet been economically feasible.
“But it is worthwhile to pursue solutions,” he said. “Life would be so much better for a lot of people.”
Article originated at The New York Times