How to turn waste water into clean water

Typically, the waste water originates from domestic, municipal or industrial use as well as from rainfall. It contains dissolved and undissolved substances, which can be of organic or inorganic origin. In some cases, waste water also contains heavy metals and salts, which are dissolved in the water. In today´s state of the art waste water treatment plants, the waste water has to pass through many different stages like mechanical, biological and sludge treatment.