Explain how wastewater can be turned into drinking water.

Wastewater can be turned into drinking water by proper treatment depending on the levels of the biochemical oxygen demand, chemical oxygen demand, metals content, alkalinity and etc. There are different levels of treatement as well, the primary, secondary and tertiary. One of the methods nowadays which gains attention because of its efficiency is the biological treatment method. This method includes the aerobic and anaerobic digestion which significantly removes BOD and COD. However, if the final purpose of the treatment is for drinking, the last step should be a membrane separation process or a sorption based process. This purifies the water to a maximum extent is designed properly.