Researchers Look to New Uses for Wastewater

Americans use – and waste – a lot of water. With an eye to sustainability and conservation, scientists are now exploring new ways to make wastewater an asset.

What is Wastewater?
According to the Water Research Foundation, Americans typically use about 60 gallons of water indoors daily. While that is a 22 per cent drop in usage from 1999 levels, toilet use, showers, and over-irrigation continue to undermine efficiency goals.

Most of this water becomes wastewater, which needs to be treated before being released back into the environment. Keeping the water clean is critical for fisheries, wildlife habitats, public health, and quality of life. Yet, powering the wastewater treatment centres is a big drain on municipal budgets and energy.

Some progress, though, is being made in terms of recycling water, which is chemically treated to be used for something other than drinking water. For example, recycled water might irrigate a golf course, cool a power plant, fill an artificial lake, or be used in industrial processes at paper mills or carpet dyers. Still, researchers are finding ways to do even more.

Making the Most of Wastewater
Researchers are working to turn “used water” into an asset. One established approach generates biogas through anaerobic digestion, in which microorganisms break down the organic waste to produce a methane and carbon dioxide mixture from which the methane is reclaimed to:

  • Power alternative-fuel vehicles
  • Produce mechanical power
  • Fuel boilers and furnaces
  • Supply homes and businesses with fuel

Hydrothermal processing is a newer approach. In this technique, sewage sludge (made of wastewater solids) is converted into biocrude oil and natural gas; this new bio-based fuel can replace gasoline and diesel fuels.

The use of microalgae, which is in the testing phase, involves scientists trying to develop and manage the variety of algal cultures that can be grown in water then extracted and converted to biofuels.

Other researchers are working to mine essential nutrients from wastewater for use in fertilizers. For instance, the Rich Earth Institute in Vermont has successfully converted ammonia from urines in the wastewater into fertiliser.

Similarly, additional researchers are working on mining minerals from society’s waste. An Arizona State University research study found 13 lucrative elements (including gold, silver, platinum, copper, and zinc) in sewage sludge; the value of recovering these 13 from the biosolids was estimated at $280/ton.