A recent study reveals that waste from 1 million Americans may contain metals such as gold, silver, lead, titanium and zinc which could be worth up to $13 million. With a population of more than 320 million, the U.S. could be a gold mine as long as scientists discover how to extract metals from waste material.
The presence of gold nuggets and other metals was discovered after researchers examined human feces through the use of an electron scanner at American sewage plants. Apart from gold, they also found traces of rare earth metals such as vanadium and palladium which are normally used in laptop and mobile phone technology.
"The gold we found was at the level of a minimal mineral deposit," said lead scientist Dr. Kathleen Smith from the U.S. Geological Survey (USGS). "We're interested in collecting valuable metals that could be sold, including some of the more technologically important metals, such as vanadium and copper, that are in cell phones, computers and alloys."
At treatment plants, wastewater undergoes a series of physical, biological and chemical processes after which end products such as biosolids and treated water are achieved. Every year, around 7 million tons of biosolids or treated waste are produced in U.S. wastewater facilities. Half of that amount is used as fertilizer in fields and forests while the remainder is incinerated or sent to landfills.
Smith and her team of researchers argue that extracting metals from waste is also an essential way of limiting the release of harmful elements into the environment and reducing the amount of toxic sewage which has to be either burnt or buried.
"If you can get rid of some of the nuisance metals that currently limit how much of these biosolids we can use on fields and forests, and at the same time recover valuable metals and other elements, that's a win-win," said Smith.
Researchers have been taking samples from various wastewater treatment plants across the U.S. every month for a period of eight years. They learned that silver is more commonly found and appears at an average of 28 parts for every million. Other metals such as vanadium, lead and copper are also found to have high concentrations. Though the findings may not represent the nation as a whole, they show that there's a lot of wealth that can be extracted from human waste every day.
Recently, a number of technological breakthroughs had been achieved in terms of waste treatment. This is more apparent among nonprofits that constantly look for technologies that could be essential in developing economies. One example is the Janicki Omniprocessor, a waste-treatment system owned by the Gates Foundation. The system converts sewage into electricity, fertilizer ash and drinkable water.
The findings were presented at the 249th meeting of the American Chemical Society taking place this week in Denver, and published in the journal Environmental Science and Technology.
Photo: eutrophication&hypoxia, Chesapeake Bay Program I Flickr
