And now for some toilet talk. The Swedish company Wost Man Ecology AB has designed a dry toilet that separates urine from solid waste and turns them both into usable manure for farming. It uses a scant amount of water (about .5 liters), which makes it ideal in remote developing areas with poor or nonexistent sewage systems, as well as in urban areas where water is a scarce resource that gets wasted through frequent flushing. Two compartments in the bowl separate liquid and solid, which require different lengths of time before they're ready for farm use.
In the context of our earlier post about agriculture in the developing world, this could be a useful tool for urban farmers who have a need for nutrient rich fertilizer and may not have safe systems for dealing with human waste. The porcelain thrones are currently on the market and 2,000 have already been sold.
The typical adult, eating a North American or European diet, urinates about half the nitrogen it takes to create the protein in a typical North American or European diet.
Nitrogen may trump carbon as an element humans have put out of balance. Recycling it is a very good idea.
This is a great idea, but humanure (a word that gets too little play) is frequently high (comparatively) in heavy metals, as well as VOCs, antibiotics, and pharmaceuticals. In urban concentrations, it should *not* be used as compost for food. Or, at least, it needs to be seriously cleaned/diluted first.
Posted by: justus on June 12, 2006 12:59 PM
Further to justus' point, I have some concerns about the waste processing in this system. I doubt that dessication and high pH kill all potential pathogens. Just off the top of my head, I'd worry about Bacillus, Mycobacterium and Clostridium spores.
I'd say a good system might look like Seattle's yard waste/composting system, where yard waste is picked up, taken to a central location, and turned to compost. The finished product is packaged and sold. Although this adds more energy and space into the system - things that potentially make it less green - it also adds a layer of monitoring, security, and oversight (things to make it more equitable).
What would be a simpler system to achieve the same results?
Posted by: justus on June 13, 2006 7:08 AM
Rochester, Minnesota does the exact same system as Seattle. I had a chemical problem in my garden last year so I got a bobcat, dug the whole thing out, and replaced it completely with the compost from the municipal compost facility. It's crazy this year, my plants are all growing REALLY well and my tomatoes are going up so fast I can't keep them tied properly!
worldchanging was founded on the idea that real solutions already exist for building the future we want. it's just a matter of grabbing hold and getting moving.
