That’s what people in Japan are doing, extracting gold from sewer drains that can rival the productivity of most gold mines out there. It used to be despised but the Japanese have again turned smelly gunk into gold of all materials. One of the most expensive commodities on the market, it is mined using million dollar machines in concentrations that gets you something like a few grams per ton of rock. Some of the biggest industrial mines obtain it chemically due to microscopic proportions making it quite a huge endeavor indeed. Location is the key and they have isolated areas that are near metal processing facilities that manufacture electronics and do plating jobs.
If I remember it right, they also extracted precious metals from muffler recycling plants where they dismantle old car mufflers extracting gold, silver, platinum and several other metals. Gold being a very expensive metal is priced at $900+ per ounce and since most major gold mines have exhausted resources, prices are going up and down at an hourly rate. Imagine having gold in your drains and old mufflers, now that’s an idea these people are good at. The Japanese have been known for their technology and unending need for innovation. From chopstick mounted fans to cool your noodles, to automated toilets that wash and heat your behind, they make them all.
Just wondering, if they happen to recover gold from sewers near industrial facilities, aren’t these plants dumping waste water into the drains? Naaah, they are known for their strict obedience to laws and knowing their pride in honor lessens my fears. Just what will they think of next, only they can answer that(hopefully it can extract the carbon dioxide in the atmosphere to heal the planet).