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The EarthAuger is a hybrid sanitation system: a urine diverting dry toilet (UDDT) and a composting toilet. A composting toilet makes use of naturally occurring bacteria that use the solids as an energy source – as food – and in the process, convert the solids to a more stable form. Composting happens faster and with greatly reduced odors if done aerobically (with oxygen); a UDDT helps with this in that the urine (and any other water) is separated from the solids by the way that the toilet seat/vertical chamber is made. The odors from poop dissipate relatively quickly, whereas as urine sits around, it really stinks over time. If both urine and poop sit together – that’s the worst conditions for odors, as the mess becomes anaerobic (without oxygen), causing ideal conditions for odor generation.

Our goal is to keep the EarthAuger as inexpensive as possible, and we have achieved that goal. Traditional collection and treatment is expensive, potentially the highest costs for large sewage systems followed by a wastewater treatment plant. Traditional wastewater treatment also presents technical obstacles. Since a mechanized treatment plant is designed to run within a narrow tuning of parameters, failure in a developing country is often just a broken part, power outage, or funding shortfall away!

A video of the EarthAuger            Installation guide            Operations guide

There are a number of ways that the EarthAuger enhances composting, drying and odor reduction. First, a cover material is added (like sawdust, coffee grounds, rice hulls, ash, etc.). These materials absorb odors as well as absorb moisture. Ideal composting happens between 40 and 60% moisture, so it’s best to reduce the moisture in poop as soon as possible in the system. Secondly, each ‘flush’ turns an auger that mixes the poop with the cover material. This action makes the composting happen faster by maintaining aerobic conditions, breaking up chunks of materials and continually moving the materials. Eventually, composting slows because the bacteria have used the solids that are easily broken-down. It's easy to tell the solids have changed form, as the material that comes out the end has a typical musty odor of rich earth rather than a fecal smell.

The black vent tube outside the toilet building also helps drying. As the sun hits this black tube, the air inside heats up, rises and pulls air down through the toilet seat and through the horizontal chamber. Any odors that are produced are carried away.

Both pedestal and squat interfaces are available. Both have seals on hinges that, when lifted, allows solids and liquids to be deposited; when down, they allow urination and washing.

Why use a UDDT composting toilet like the EarthAuger? Here are a few reasons:

  • It requires no water to operate
  • It doesn’t use energy
  • it has little odor or flies
  • it produces two usable end products: compost (great for the soil) or for making energy pellets, and urine (a great liquid fertilizer)
  • It’s easy to use and maintain
  • it can be used in difficult situations like areas prone to flooding, shallow groundwater, or unstable ground
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