This article on our humanure hack provides background to the humanure album containing 'how to' pictures covering a simple, low cost composting system.
This humanure hack is really affordable. If you have a little time there is no reason not to go partially off grid with sewerage and drop your water use enormously.
However, adjustments to this system such as buying a composting toilet could make it amenable to people who want a higher level of cleanliness. People with more money could do a feedback loop from gray water to the cistern, and remain on grid with their sewerage. These units are available at local plastic companies like Plastics for Africa.
One way I save water is showering only once a week at the gym and severely limiting the washing of clothes. I hope to cut it even further by cleaning up the water we do use in the kitchen and bathroom by putting it through a gray water bio-processing system to remove fats, excess salts and pathogens.
Such cheap methods are not for everyone, the bathroom is not so pretty, and the process is hands on, albeit very low maintenance, but it is not fully automated and wealthy, busy people understandably want something more sophisticated.
The cleanliness issue is not just about appearances. Certain bad strains of E. coli in the human gut are deadly to those who consume them. People die of E.coli infection in the most developed of countries like the United States, see CNN and Wikipedia from consuming foods like bagged spinach, bean sprouts, soy nut butter, mince and meat. The foods are diverse. In the US there is a problem with antibiotic dosed intensive cattle farming producing resistant strains that find their way into the foods in supermarkets and restaurant chains via the meat of the animals infected, or through the use of their manure as compost. This danger is limited by various factors, but in a system where the bacteria of many humans are being composted without good practice, an outbreak could occur.
This humanure hack is a compromise. One does not compost the urine with the feces, like they do in the global humanure online group on facebook. The urine goes down the toilet which is flushed with gray water from the handbasin. One can collect this gray water in a bucket by removing the U-bend. As there is only urine and gray water going down the toilet in small quantities, with no flushing which uses extravagant amounts of water, it is important to put no toilet paper in the toilet, as it can create blockages further down without the large amounts of water from the cistern when you flush the toilet.
No toilet paper goes in the toilet, but instead it goes into baskets or straight into the bucket depending on whether it has been contaminated with feces. The implications are that there is less nitrogen in the composter pile and it does not get quite as hot, but there is also less liquid potentially leaking out of the pile full of E.coli. With a tiny garden, introducing the massive amounts of nitrogen found in urine may cause a short term fertility boom, but in the long term it could unbalance carbon nitrogen ratios (see my pages on hot composting) and speed up decompositional processes in the soil. This revved up decomposition is a factor that is leading to global desertification, through the use of mineral nitrogen fertilizers. The removal of soil carbon leads to ecological disasters like those seen in the films by John D. Liu. Urine should be used where it balanced by being spread thin and combined with thirty times the amount of carbon rich material. In some contexts this is just impossible.
Buy a small bowl that fits exactly in the toilet bowl. Line the plastic bowl with newspaper, two sheets thick, place it in the toilet, do your number two, lift out the parcel by lifting the points of the newspaper, and plop it in the collecting bucket with any soiled toilet paper and close the lid. When the bucket is full you can store it outside, if you have a number of buckets, or you can compost immediately. To do this build a box or nest of straw in the composter for your ‘deposit’. Make sure the floor of the box is very thick with 50cm of straw or compost, and place a thick straw lid on the box to stop flies and odours. There is no lasting odour from this process. The newspaper in the bucket prevents odours in the bathroom while the bucket is filling over several weeks, and once covered with straw I one can smell nothing. The straw and the paper is ‘carbon rich’ and they absorb excess nitrogen and odours, and help ensure a predominantly aerobic composting process.
The composter is built from pallets fastened with cable ties in a few minutes. The composter has a movable loose pallet as a base, and the sides allow air in too. The bottom pallet is loose so that one can remove it to clear the ground after composting for one year, so that air can get into the pile from below again. After assembling the pile insert a metal probe. Check a few days later. It will almost burn your hand, which should be washed thoroughly afterwards.
This individual humanure hack is not perfect, and it is not truly sustainable. Everyone cannot compost or collect straw in the park, we would be fighting over it.
The straw should also ideally be left in the park to decompose, but the city workers tell me they remove it and it goes into the landfills mostly so all in all, taking the straw from the park is a better solution in the short term.
I am working on an integrated design for a full compost toilet and food growing system. Various other tweaks should make this project totally sustainable in time.
If you have any questions please let us know !
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