Device Mines Precious Phosphorus From Sewage 96
ckwu writes "Scientists predict that the scarcity of phosphorus will increase over the next few decades as the growing demand for agricultural fertilizer depletes geologic reserves of the element. Meanwhile, phosphates released from wastewater into natural waterways can cause harmful algal blooms and low-oxygen conditions that can threaten to kill fish. Now a team of researchers has designed a system that could help solve both of these problems. It captures phosphorus from sewage waste and delivers clean water using a combined osmosis-distillation process. The system improves upon current methods by reducing the amounts of chemicals needed to precipitate a phosphorus mineral from the wastewater, thus bringing down the cost of the recovery process."
Re:Now if we can get this device onto storm drains (Score:5, Informative)
It varies from municipality to municipality. Some directly drain into local streams, others go into sewer systems, and some have separate systems.
Re:Now if we can get this device onto storm drains (Score:5, Informative)
Storm drains generally separate from the sewage system; the cost of treating hundreds of thousands of gallons of extra rainwater would bankrupt most communities. That's why it's usually illegal to dump waste into the storm drains.
Re:Not scarce, no rare (Score:5, Informative)
In 2012, the USGS estimated 71 billion tons of world reserves, where reserve figures refer to the amount assumed recoverable at current market prices; 0.19 billion tons were mined in 2011.[23] Recent reports suggest that production of phosphorus may have peaked, leading to the possibility of global shortages by 2040.[24] In 2007, at the rate of consumption, the supply of phosphorus was estimated to run out in 345 years.[25] However, some scientists now believe that a "peak phosphorus" will occur in 30 years and that "At current rates, reserves will be depleted in the next 50 to 100 years."[26] Phosphorus comprises about 0.1% by mass of the average rock, and consequently the Earth's supply is vast, although dilute
From http://en.wikipedia.org/wiki/Phosphorus#Occurrence [wikipedia.org].
"Peak phosphorus" sounds like "peak oil", but there does appear to be a number of people afraid of future scarcity. However, the ability to cheaply precipitate phosphorus out of sewage waste (and hopefully, with a few tweaks, out of agricultural runoff also), could significantly reduce dead zones [wikipedia.org], especially the Gulf of Mexico dead zone. That seems reason enough to pursue this.
Re:Now if we can get this device onto storm drains (Score:5, Informative)
An effective, lower-tech method (Score:3, Informative)
A community-scale pilot project by the Rich Earth Institute [richearthinstitute.org] is demonstrating a fairly low-tech and cost-effective way to reclaim two thirds of the phosphorus and 85% of the nitrogen from human waste: recycling urine (which is nearly sterile and can be further sanitized very easily) directly into fertilizer. (Yes, #1 really does have a lot more fertilizer value than #2!) It's also being done in various public projects in Europe, Africa, and Asia, and by lots of gardeners around the world. There's also this book [liquidgoldbook.com] that talks about the history of urine as an industrial feedstock and modern methods for using it as a fertilizer at large or small scale.
Re:Fancy technology (Score:5, Informative)
Assuming you don't fuck up the composting (not always a safe assumption, once the system moves into volume production and management by people who have to make budget) the stuff is largely pathogen free; but that doesn't do anything about anything that microorganisms that thrive on sewage don't help you with. Heavy metals, some drugs, some hormones(synthetic or not), some endocrine disruptors, any random plastics that end up down the sink, and so on. The concentrations aren't apocalyptic; but if you plan on routine use as fertilizer, better hope that they don't build up in the soil...
So called 'class B' sludge, where they don't even bother treating for pathogens, is of course even more fun than 'class A' where you only have to worry about anything that bacteria won't eat.
Re:Now if we can get this device onto storm drains (Score:4, Informative)
That's because NYC's sewer system is so old that when it was originally built, there was no such thing as a sewage treatment plant. They could use one set of pipes because everything was just getting dumped into the harbor anyways. Now that they have plants, they retain a problem of having to dump untreated sewage in the harbor when the plants get overloaded during storms.
If your municipal water system was built after activated sludge control became common in the 1930s, storm water is probably handled separately from sanitary sewage.