This Device by Filipino Electronics Engineering Students Generates Electricity Out of Wastewater. GineersNow, March 13, 2017.
When John Paul Santos noticed the wastewater in the Pasig River which is near to his school the Polytechnic University of the Philippines, he had a thought of using such water to generate electricity. It was a wild idea then. 
But being in his second year as an electronics engineering student, he knew he had to do something about it. Eventually he did.
Together with fellow electronics engineering student Christian Sta. Romana, he developed a device called Electrifilter, or electricity generation from filthy water, which does exactly what is called. It can produce electricity from filthy water which first samples were from the Pasig River.
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