Imagine wearing gold and other precious metals from raw sewage? That is what scientists are looking into saying they can harvest amounts of metals such as gold, silver and platinum.
If they can succeed in doing so, then it could reduce the need for mining and decrease the amount of metals polluting the environment while also turning sewage into a source of revenue.
You may ask the question, how possible is it to get metals in waster mater in the first place and what are those metals in the waste?
According to lead scientist Kathleen Smith of the US Geological Survey, metal from sources such as detergents, hair care products and antimicrobial clothing enter the waste stream in wash water, and end up getting combined with fecal matter at waste water treatment plants.
After the treatment process is complete, approximately 50 percent of the resulting bio-solids are used as fertilizer, while the other half are put in landfills or incinerated (in the US, at least). The presence of metals in the bio-solids is one of the reasons that a greater amount of them can’t become fertilizer.
To retrieve those metals, Smith and her team are considering utilizing chemicals that would cause the metals to leach out of the bio-solids.
The same type of chemicals are currently used in the mining industry for extracting metals from rock, and their use in that application is controversial – despite the presence of safeguards such as liners and drainage systems, they can make their way into the groundwater and pollute it. In the case of bio-solids treatment, however, Smith believes that the chemicals could easily be contained.
In order to evaluate the economic feasibility of the system, the researchers have used a scanning electron microscope to analyze bio-solid samples from small towns, rural communities and big cities. According to Smith, they found gold “at the level of a minimal mineral deposit” – in mining terms, this means that it might be financially worthwhile to extract.