What are the possibilities of recycling sewage water into fertilizer? We do it with dung. Why not sewage?

Question

There must be a safe way to keep contaminants out of the finished product.

Answer 1

It's been tried a long time ago. I believe the product was called "Milorganite," and I understand it was discontinued when they found excessive amounts of toxic metal contaminants in it. [Selenium, in particular]  It would be fine for flowers but growing food with milorganite was unsafe.

Answer 2

solve two problem at once.

use the Fischer-Tropsch process to make oil from trash sewage old tires anything organic.

http://en.wikipedia.org/wiki/Fischer-Tro...

http://www.zero.no/transport/bio/BtL%20N...

http://www.greencarcongress.com/2006/03/...

http://www.greencarcongress.com/2006/09/...

http://www.technologyreview.com/BizTech-...

http://www.eia.doe.gov/oiaf/aeo/otherana...

this would give us oil plus stop the need for landfills

it also would also clean up our rivers by keeping the drugs and toxic chemicals coming from landfills and sewage treatment plants from polluting them.

since you can make oil from trash and sewage for about $90 a barrel this would undercut the oil companies and drive down the price of oil.

that would drive down the price if gas and diesel.

Answer 3

I heard a story on NPR not too long ago about a place that's using a series of swamp-like fields to purify the water naturally.  Only problem is that it takes quite a bit of space so it's not good for metro areas.

Answer 4

Right now, biosolids (which is dewatered municipal sludge) are in fact land-applied as one disposal method.   But it is put only on fields that grow animal food or some such.  You can not put it on human crops.    

Let's face it, you just don't want all the medicines and diseases that are flushed down our toilets to be put DIRECTLY onto our food.   It's a recipe for a public health disaster, and it is (in part) why you can not safely eat fresh leafy produce in many parts of the world.  

Further, anything that you put onto fields will eventually leach into the water supply.   This is the big argument AGAINST land-applying it at all.   There is a lot of attention currently at anaerobic digestion, which is a way of getting the energy content out of the sludge (in the form of hydrogen, mostly).  

Safely disposing of human waste without making people sick is a surprisingly tricky thing to do, honestly.

Great question.

Answer 5

they just partially treat it and spray it on the fields here. with water shortage and increase in city dwellers, its going to be an increasingly valuable resource. my favourite idea is biodigestion; get methane out instead of CO2 by using anaerobic decomposition instead of aerobic, collect it for energy generation, and the solid end product has been heat treated and broken down beautifully to a good grade soil conditioner, is easy to handle and nicer safer than slurry.

http://www.anaerobic-digestion.com/