Building a composting latrine is not difficult, but must be carefully managed to be safe.
Many Peace Corps volunteers and others working in sustainable development have built composting latrines around the world. The idea behind a compost latrine is to dispose of human waste in a hygienic manner to discourage disease transmission, then to compost the material for use as a soil enhancer for growing gardens and crops. Composting the human waste can be done either quickly in three to four weeks, or slowly over a period of two years. While a composting latrine is a workable concept, education on the composting process is necessary for the composting latrine to be well managed and maintained. Does this Spark an idea?
Instructions
1. Find the site for the latrine. The latrine should be at least 30 meters from a clean water supply (rivers, wells or springs), approximately 5 meters from the house (preferably downhill and downwind), and 2 meters above the groundwater table. The latrine should be either above ground or on top of a mound of dirt.
2. Dig two vaults, each .5 to 1 meter deep, 2 meters wide and 2.4 meters long, for a slow composting latrine. Place the PVC pipe to vent the vault to the outside. When one vault is full, cover it and leave it for two years so all the pathogens in the human waste will break down. At that point, the compost can be shoveled out and used on the fields. The other vault is used until it is full and the process begins again.
3. Dig one vault for the fast composting process. Place a bucket in the outhouse for urine collection; urine can be diluted and used on garden soil as a nitrogen-rich fertilizer. Place a bucket of sawdust for use on the waste in the latrine house. After each use, scoop some sawdust, grass or dirt over the waste to keep down odors and prevent insects. Cover the waste sufficiently.
4. Shovel out the material and move to a place for the compost when the vault is nearly full. A simple compost bin 3 feet square and 4 feet deep can be used. Add the sawdust and waste mixture from the latrine.
5. Add the other compost materials, layering on the carbon and nitrogen components until you have the correct carbon to nitrogen ratio (in this case, two parts carbon to one part nitrogen). For fast compost, all the materials for the compost must be added at the same time.
6. Add water until the compost is as damp as a wrung-out sponge. Try to keep this level of moisture, not too wet and not too dry.
7. Use a pitchfork to turn the compost to incorporate air after one week. Aerobic hot composting needs air to help the soil microorganisms break down the decomposing waste.
8. Stick the thermometer into the center of the compost to check the temperature. A good, fast compost should be between 130 and 170 degrees F. The heat of a fast compost kills pathogens from the human waste.
9. Allow the compost to work longer to ensure that all pathogens from the human waste are dead, even though the compost will have broken down the waste and other ingredients in three to four weeks. Let it set for two weeks or a month to cure and stabilize pH levels.
10. Use the pathogen-free compost to mix with garden soils and spread on fields for crops.
Tags: human waste, composting latrine, fast compost, break down, carbon nitrogen, compost materials, composting process