Some academics and start-up businesses believe that
wastewater is a veritable treasure trove of select raw materials, as one publication discovered.
Greentech Media has compiled a list of companies that are looking close to home for uncharted deposits of natural resources.
One example is Agroplast, a small firm located in Ishoj, Denmark, which has created a design for a feedlot which automatically collects the urine and separates out the urea from pigs' waste.
The urea can then be used in plastics and in engines to reduce emissions.
Meanwhile, New Zealand's Carbonscape makes eco-coal by compressing organic matter, including sewage.
The substance burns like its standard counterpart but the carbon does not come from deep in the ground.
Another unconventional use for
wastewater is water bottles, which Greentech describes as "microbial sewage".
Ireland's Bioplastech recycles old plastic containers with microorganisms, which eat a cooked-down version of the bottles and metabolise them into new plastic.
Written by Lauren Steadman