Recycling wastewater for drinking
Currently one billion people around the world do not have access to clean water for drinking. The amount of freshwater that is available is also declining due to climate change. The Columbia University’s Earth Institute blog noted this and suggested ways of replenishing freshwater sources by treating wastewater to potable standards, and highlighted a few cities and countries around the world and the methods they use.
The City of San Diego ran a Indirect Potable Reuse (IPR) project from 2009 to 2013 which demonstrated that advanced water purification technology could provide safe drinking water. The advanced water purification technology included microfiltration, reverse osmosis and disinfection by ultra violet light (UV) or ozone and hydrogen peroxide. The water recycled by this method is piped to groundwater or surface water reservoirs to replenish the freshwater sources.
The Orange County Water District in California is world-renowned for its Groundwater Replenishment System (GWRS), which is the world’s largest water purification system for indirect potable reuse. Using advanced treatment processes (microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide), it treats the water to a quality that meets or exceeds state and federal drinking water standard. The water is then pumped into injection wells to act as a seawater intrusion barrier and into recharge basins which empty into the deep freshwater aquifers.
Using the same advanced treatment processes as the City of San Diego and the Orange County Water District, Singapore produces recycled water purified which it branded NEWater. NEWater is piped to various industries that require ultra-pure water, and some of it is added to local reservoirs and bottled as drinking water.
Although many people have reservations about drinking recycled water, scientists did not find any adverse health effects in populations that use recycled water. An example of a country that has been recycling wastewater for drinking purposes is Namibia, which started its recycling program since 1969. Recycled wastewater can be a sustainable source of clean drinking water. As the population in cities grow, it will become necessary for more cities to replenish their freshwater sources, and to inform and educate the public about the safety of drinking recycled water.