VOA标准英语2013--Students Invent Water Purification Disc（在线收听）

Students Invent Water Purification Disc

The lab operates like a kitchen. They add several ingredients. Then they mix, weigh, press and bake them.

What's created is called a MadiDrop - a ceramic disc infused with silver.

When dropped in water, silver ions, which are atoms that have an electrical charge,, are released to purify the water.  And, testing here at the University of Virginia shows clean, safe water.

“It's not just about making a really great technology that effectively removes or kills bacteria and pathogens.  It's about making a low cost, simple to use one, tailored to people in developing countries who don't have many resources,” said Beeta Ehdaie, a doctoral candidate at UVA.

The students are experimenting with different sizes of MadiDrops to correspond with different sized water containers.  Why the name “MadiDrop”?  

The word “madi” means water in Tshivenda, a language of Limpopo Province in South Africa. Fifty women run a water filter factory, set up by the university in the province last summer.  

The women mix sawdust and clay and make flower pot shaped filters that they use to purify drinking water.

The water flows through the filters to trap bacteria and solid particles. The factory sells the filters to local families. Manager Certinah Khashane says the work has changed the women's lives.

“When they get money for those pots, they buy school uniforms for their children,” Khashane said.

But the MadiDrop is smaller and less expensive than the filters.  So, over the next few months, students will conduct field trials of the MadiDrop here in South Africa.

Water experts say further testing will determine if the MadiDrop is indeed a breakthrough. Maggie Montgomery, who is with the World Health Organization, explained what field testing should reveal.

“Do they find it convenient, does it have a certain taste they don't like to the water, what happens once it becomes exhausted?,” she said.

If successful, the South African women will produce and sell MadiDrops. The goal is to expand the existing factories to other developing countries and impact millions of lives per year.

“Imagine a magic stone and you take this magic stone and you drop it in your water container.  It purifies the water and makes it safe to drink.  And then imagine that this magic stone only costs a few dollars. That's what a MadiDrop is,"  said Jim Smith, the engineering professor leading the project.

The project has been presented to the American Chemical Society and the American Society of Civil Engineers.  Smith says he's received calls from corporations interested in producing the MadiDrop....which might mean Smith and his students have truly invented a magic stone.