Skip to main content

Mining for Metals in the Waste We Create

John has recycled metals most of his life and is fascinated by waste that has value. Recycling made him aware of its necessity—and worth.

Treasure in the Sidewalks

Nothing could be more blasé than walking, head bent down, and passing concrete sidewalk sections and expansion joint dividers, one after another. But in bustling urban jewelry quarters, a new kind of gold prospecting is taking place. Gemstones, silver, platinum, and especially gold are being mined from sidewalk cracks full of years' worth of traffic dirt from customers walking in and out.

Shoe Soles May Be a Cornucopia

You see, minuscule pieces of precious metal can be retrieved from this dusty accumulation of what seems nothing. Just like the gold prospectors of bygone days, these folks scrape the dusty cracks and concrete joints seeking their hidden bounty. Flakes of gold foil, tiny pieces of gold from repairs, and gold powder from cuttings, along with the occasional diamond, ruby, or emerald chip is their holy grail. Gold is soft and easily sticks to the soles of shoes. Chips can get lodged a bit in those soles and then deposited outside a doorway. The same goes for other precious metals.

Because workers in the jewelry business know how valuable their materials are, you can see jewelers brushing and vacuuming their work benches, clothes and shoes. Sinks are often equipped to save wash water lest fragments of gold be washed down the drain. The water can be panned later. Some small pieces accumulate in drains inside and out of jewelry stores. Even nearby streets, roads, and dumpsters can harbor the remnants of a jewelry shop's work.

Valuables in Front of You

Given that there have been several studies regarding thrown away money, the U.S. Mint roughly calculates between 66 and 77 percent of pennies each year are discarded one way or another. The Transportation Security Administration found $617,000 in spare change at airports in 2014.

One man started collecting change at a carwash, and finding it lucrative, he kept track. After one year—from that carwash alone—the New York man found over $1000.

Is it any wonder why precious metal can be found in sludge? Millions of pedestrians walk billions of times over pathways, sidewalks, and streets. How many have unknown holes in their pockets? How many necklaces accidentally break and fall due to fiddling fingers? What about bracelets or necklaces that are ripped off with a gold link or chain falling to the ground? Broken earrings are another commonly lost jewelry item. And with all of the manufacturing going on, we know there is a lot of silver, platinum, and gold to be stumbled upon.

Waste Not Want Not

When biosolids are separated from effluent and dried, it becomes sludge. In some countries, the sewer sludge is gathered and sifted to extract precious metals. This can be especially profitable in third world nations.

In Japan, the sludge, or what remains after the sewage is treated, is collected. In Suwa in Nagano Prefecture, a treatment plant near a large number of precision equipment manufacturers reportedly collected nearly 2 kilograms of gold in every metric ton of ash left from burning sludge, making it more gold-rich than the ore in many mines. The Japanese prefecture (similar to a U.S. county) has been mining its sewage treatment plant for the last 10 years. In 2008, it recovered $168,000 worth of gold. The recovery value is based on fluctuating gold prices.

Pumpkin seedlings planted out on windrows of composted biosolids at community compost education garden - gold and silver can be found in sludge from biosolids. 60% of sludge is recovered and used for fertilizers.

Pumpkin seedlings planted out on windrows of composted biosolids at community compost education garden - gold and silver can be found in sludge from biosolids. 60% of sludge is recovered and used for fertilizers.

Pig in a Poke

One's perception of what is hideously disgusting can change.

Street gutters can be extremely odious with their gummy black coats. Yet, in the very same gutters, there is a good chance of finding valuable metal. Vanadium and platinum can be found in these street-side troughs. These metals are discharged in small amounts by automobiles all day long.

Vanadium, a steel hardener, is being discharged by machines used for crushing, grinding, and cutting. Folks working in the industry use vanadium tools, and those tools are being sanded, chipped, and dropped daily. At shift's end, the bits left behind are washed down the drain by clean up crews.

Platinum and lead are also found in the street. Lead is found in pipes, storage batteries, weights, fishing sinkers, shot, and cable covers. Platinum is used in the lining of converters, and when worn over time, small particles are released in exhaust, only to fall to the ground. Larger pieces can flake off with time.

If this material could be collected and separated economically for recycle, it might make a difference to the environment and reduce public expenditures to remediate pollution. Researchers in India have separated vanadium oxide from sludge. English researchers have separated vanadium from industry sludge.

Extracting Gold From Poop

As environmental engineering becomes a topic of increased interest, gold and silver mining at water treatment plants is at the forefront. In 2009, Kathleen Smith, a U.S. Geological Survey researcher, claims that in her study of sewer plants producing more than one million gallons of sludge, an average of 30 mg of silver per kilogram (2.2 pounds), 563 mg of copper per kg, and 36 mg of vanadium per kg were found.

In another study at Arizona State University in 2015, Paul Westerhoff estimates that there could be as much as $2,600,000 worth of gold and silver produced from poop in cities of just one million inhabitants. When the sludge is incinerated, the ash that is left behind is even richer in precious metal.

It's hardly a pile of crap if you know what I mean.


Eaton, Kit (2009, December 2). Mining Poop for Gold, Retrieved November 3, 2019 from

Doyle, John (2011 June 20). Man digs for treasure on streets of NYC, Retrieved November 3, 2019 from

Cornwall, Warren (2015 January 16). Retrieved November 4, 2019 from

Panko, Ben (2017 October 12). Retrieved November 4 from

Von Radowitz, John (2015 March 24). Retrieved November 4, 2019 from

Gannon, Megan (2015 March 24). Retrieved November 4, 2019 from

T.K.MukherjeeS.P.ChakrabortyA.C.BidayeC.K.Gupta (2016, October 10). Retrieved November 5,2019 from

Kulmann, Joe (No Date). Retrieved November 5, 2019 from
Bartiromo, Michael (2019 October 23). Retrieved November 6, 2019 from

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2019 John R Wilsdon