![](https://cos-cdn.shuashuati.com/pipixue-web/2020-1231-2005-12/ti_inject-812ce.png)
One system using solar energy to clean up pollution in water has banks of moving mirrors that focus sunlight onto a waterfall of waste water. The other method reflects light from a mirrored trough onto waste water flowing through glass tubes. The solar purifiers will reduce concentration of organic pollutants to a few parts per billion. Two methods for water t______ with solar energy.