Can be useful to developing country: Waste water can generate electricity

American scientists have built a device that can generate electricity from waste water.

BBC said the team from Pennsylvania State Universitysaid the technology would simultaneously also treat the water. The scientists suggested the process could be adopted in developing countries to provide clean water as well as power for homes.

The study has been published in the journal Science.

Device that can generate electricity from waste water

Researchers in the Netherlandshave for some years been exploring the idea of generating power along the country's coastline, where fresh water from rivers meets the salt water of the sea.

Using a process called "reverse electrodialysis", fresh water and seawater are placed in intermittent chambers separated by membranes, and an electrochemical charge is created.

The Pennsylvania team, however, said the reverse electrodialysis technology was problematic because of the large number of membranes required, and because power plants have to be located near the sea.

The number of membranes can be reduced and the power output boosted by combining the technology with what are called "microbial fuel cells". These use organic matter in solution -- in this case waste water -- to create electric current.

Lead researcher Bruce Logan told BBC: "In our process, we have the microbial fuel cell part which is treating waste water and creating energy, and we have the reverse electrodialysis stack which is just boosting that process, it's making it happen more efficiently."