The city utilizes manure to provide clean water

By making electricity from stools to operate water supply systems, a city in Denmark has created a rare feat.

Clean water is something that is rarely associated with sewage. But Aarhus - the second largest city in Denmark - is making the connection between them by becoming the first urbanized world to use sewage to provide clean water.

The Aarhus Water Treatment Plant in Aarhus is producing electricity from sewage and they use excess electricity to pump water to every household in the city, New Scientist reported. In addition to pumping water, the plant also sells excess electricity to the local grid.

The electricity production process is as follows: Sewage pumping plants into large tanks with a fixed temperature of 38 degrees Celsius and contain bacteria.

Waste water production system of Aarhus Water Treatment Plant. Photo: New Scientist

Bacteria and heat convert waste water into gas - a mixture of gases produced by the decomposition of organic compounds. The plant burns gas to generate energy in the form of heat and electricity.

" We do not add any organic material to sewage," said Lars Schroder, general manager of the Aarhus Water Works.

The investment for the power generation system from sewage is quite large - with an initial investment of $ 3.2 million.

Aarhus Water expects to recover its capital after five years from saving factory maintenance and selling excess electricity to the network.

Aarhus Water is the first water plant in the world to produce more than 50% of its electricity consumption, according to the Danish Ministry of the Environment and Food. Eva Kjer Hansen, the minister for environment and food, says waste water treatment plants must shake off the image of " excessive consumption of electricity " to become an electricity producer.

" We have a typical example in Aarhus, " she said.

Governments in many other cities around the world - including Chicago, San Francisco - are interested in adopting the Aarhus-like model.