Waste Water Re-Use!

Many gallons of water are saved each day by reusing wastewater. The problem with this is the treatment process causes emissions of nitrous oxide (N₂O), a greenhouse gas, to be realeased into the atmosphere.
Waste water is the water that consumers literally flush down the drain. It is also the water that has been used for cleaning and for other industrial purposes. Wastewater must be sterilized before it can be sent back to the consumer for reuse, to remove any health threats.

"Nitrogen removal process and nitrous oxide formation

The removal of nitrogen from waste waters is a two-stage process. In the first stage, the ammonium ion (NH₄⁺) is converted to the nitrate ion (NO₃^-); this part is called nitrification. In the second stage, the nitrate ion is converted into molecular nitrogen (N₂); this is named denitrification.
During both these processes, there can be a release of nitrous oxide (N₂O). N₂O is a gas with very high greenhouse gas properties; its Global Warming Potential (GWP) is 298 times higher than that of carbon dioxide.
If the nitrogen removal process is applied at industrial scale for waste waters treatment, relatively high quantities of N₂O could be formed and, consequently, released into the atmosphere."


Read more at:
http://www.decodedscience.com/greenhouse-gas-emissions-from-water-treatment-plants/3218
 - - David Honey