For decades, sewage has been treated and used for irrigating crops, parks, and golf courses, but making it fit for human consumption requires a much more rigorous filtration technology using polymer membranes. No thicker than a human hair, the membranes are at once delicate and durable. Using pores smaller than one-millionth of a millimeter, they’re capable of wiping out microscopic contaminants. ... the water division at Dow Chemical, he pulls in more than $1 billion in sales annually. The membrane market is growing more than 10 percent a year in part because of increasing water scarcity worldwide and ever more pressure to develop drought-proof water supplies from new sources. ... The whole concept of recycled sewage might be harder to swallow if there weren’t already so much sewage in the water sources we routinely draw from. ... the very reason chemists created these synthetic membranes decades ago is that, increasingly, humans have been contaminating the water supply. Industries have emerged, meanwhile, that need purer water for manufacturing. Most major players in the automotive, beer and wine, food processing, petrochemical, pharmaceutical, and semiconductor industries, for example, rely on water purified by membranes. ... recycling wastewater is about half the cost of desalinating ocean water: Both use RO membranes, but the salinity of ocean water is much higher, so it’s harder and much more energy-intensive to pump it through the tiny holes.
If water is not managed better, today’s crisis will become a catastrophe. By the middle of the century more than half of the planet will live in areas of “water stress”, where supplies cannot sustainably meet demand. ... Where water is available, when and in what condition matters hugely. About 97% of the water on earth is salty; the rest is replenished through seasonal rainfall or is stored in underground wells known as aquifers. Humans, who once settled where water was plentiful, are now inclined to shift around to places that are less well endowed, pulled by other economic forces. ... As people get richer, they use more water. They also “consume” more of it, which means using it in such a way that it is not quickly returned to the source from which it was extracted. ... To make matters worse, few places price water properly. Usually, it is artificially cheap, because politicians are scared to charge much for something essential that falls from the sky. This means that consumers have little incentive to conserve it and investors have little incentive to build pipes and other infrastructure to bring it to where it is needed most. ... around a fifth of the world’s aquifers are over-exploited. This jeopardises future use by causing contamination. It also damages the layers of sand and clay that make up aquifers, thereby reducing their capacity to be replenished. ... People do not drink much water—only a few litres a day. But putting food on their tables requires floods of the stuff. Growing 1kg of wheat takes 1,250 litres of water; fattening a cow to produce the same weight of beef involves 12 times more. Overall, agriculture accounts for more than 70% of global freshwater withdrawals. ... estimated that agricultural production will have to rise by 60% to fill the world’s bellies. This will put water supplies under huge strain. ... Hydrologists expect that a warming climate will see the cycle of evaporation, condensation and precipitation speed up. ... There is no single solution for the world’s water crisis. But cutting back on use, improving the efficiency of that use and sharing out water more effectively would all help.
Smash an old TV, and you risk spewing lead into the air. Crack open an LCD flatscreen, and you can release mercury vapor. Mobile phones and computers can contain dangerous heavy metals such as cadmium and toxic flame retardants. Mexican workplace regulations, like those in the U.S., require e-waste shops to provide such safety equipment as goggles, hard hats, and masks. There’s little of that in Renovación. ... In much of the world, a place like Renovación couldn’t exist, and not only because business owners wouldn’t be allowed to employ people in those conditions. Twenty-five U.S. states and Washington, D.C., home to 210 million Americans, have laws establishing what’s known as extended producer responsibility, or EPR. That means electronics makers must collect, recycle, and dispose of discarded equipment rather than allow it to enter the waste stream. Parts of Europe also have this system. ... Manufacturers don’t do this work themselves. Typically, a state, county, or town establishes an e-waste collection program. Then recycling companies come to haul away the junk. The manufacturers pay some or all of the bill. The e-waste can be of any provenance. ... The lack of a formal, regulated recycling industry is one of many reasons Mexico has become a magnet for spent electronics. ... A ton of mobile phone circuit boards can produce 30 ounces of gold, worth about $39,000 at current prices.
Like oil and coal, kitchen scraps can be converted into energy. But unlike oil and coal, which are expensive to dig out of the ground, food waste is something that cities will actually pay someone to haul away. Many innovative municipalities, in an effort to keep organic material out of dumps — where it generates methane, a greenhouse gas — already separate food from garbage and send it to old-fashioned compost facilities. There, workers pile the waste in linear heaps called windrows, mix it with leaves and grass clippings and let oxygen-dependent microbes transform the gunk into lovely dark fertilizer. But the more material you compost, the more space (and gas-guzzling bulldozers and windrow turners) you need to process it. It can get a little smelly, too, which is yet another reason New York City, which generates about one million tons of organic waste a year, will probably never host giant compost farms. ... But anaerobic digestion, in which food is broken down by microbes inside tall, airtight silos, has a real shot at scaling near densely populated areas. The footprint of such plants is relatively small, and their odors are mechanically contained, if they are operated properly. Digesters do cost more to build and run than compost sites, but they more than make up for that by generating two separate revenue streams: fertilizer and biogas, which is chemically similar to natural gas and can be burned to make heat and electricity. ... The nation’s industrialized compost operations bring in roughly $3 billion annually; American farmers bought $21.2 billion of conventional fertilizers in 2016.