How Wastewater Could Help Solve the World's Water Crisis

Life on Earth is dependent on water, and yet human practices are a growing threat to this fragile resource. In its latest report, the United Nations warns about the need to recycle wastewater to curb the water crisis and also protect the environment.

Every year on March 22nd the World Water Day is celebrated. It’s an occasion for the United Nations to issue its traditional annual World Water Development Report, usually devoted to the accessibility of water. But this year, the main theme of the WWDR 2017 is wastewater management, which remains an underutilized resource. Today, 80% of the world’s wastewater is discharged without treatment. That’s just, well, a waste.

Going Beyond Clean Water Supply

While water can be reused over and over again, the focus has been on supplying clean water.

“Up to now, decision makers have mainly focused on supplying clean water rather than managing it after it has been used.” Said Richard Connor, lead author of the report.

As an example, astronauts in the ISS have been using the same water for years. In the United States, the water of some rivers is recycled up to 20 times before getting to the ocean.

The situation is particularly alarming in low-income countries where on average 8% of wastewater is treated, compared with 70% in high-income countries. WWDR points out that 1.8 billion people in the world drink polluted water. Contaminated water, coupled with the lack of hygienic value, costs the lives of more than 800,000 people per year worldwide. Water diseases are one of the leading causes of mortality in the world (3.5 million fatalities), claiming more lives annually than AIDS and car crashes combined.

Wastewater Treatment Generates new Resources

Beyond health and environmental issues, the report calls for broadening wastewater treatment by organizing the reuse of wastewater through decentralized systems to reduce volumes discharged into the environment.

The most feasible prospect is, of course, the use of treated water in agriculture, which accounts for about 70% of the world’s demand for this resource. This is the case for Jordan and Israel, which recover 90% and 50% respectively of agricultural water for reuse (that same number is only 10% worldwide).

Reclaimed water can be reused in irrigation, wetlands and aquifers restoration, and even drinking (San Diego and Singapore are examples of where this takes place), but not only. Wastewater contains raw materials minerals (phosphorus, nitrogen, and biogas) and energy that can be effectively harvested. The city of Osaka, Canada produces 6500 tons of solid fuel per year from 43,000 tons of sewage sludge. In 2015, Japan issued a law requiring sewage operators to use biosolids as a form of energy.

It is also possible to treat gray water (from sinks, baths and washing machines) for domestic use that doesn’t require potable water. For example, gray water can be used to flush the toilet or water houseplants.

Check out this cool TreeHugger guide to reusing gray water in your home.