Biogas Digester Complete

After nearly a month, the digester is finally finished.  It was undoubtedly a big project that took both technical know-how, building expertise, and logistics.  Luckily, everyone involved was able to contribute something to the project and we can now say that this stage of the project has been a success.  The next stage of the project involves actually getting the thing to produce gas and cooking the learners their break-time porridge that they so desperately desire.  The learners thus far have been slow holding up to their end of the bargain - bringing cow manure.  We are still waiting for a big enough pile to accumulate before we actually feed the digester.  Also, we have a mighty digester, but no stove.  After much effort trying to track an actual biogas burning stove down in the region, we have had to resort to our friends in China.  We expect the stove to be delivered some time in August which is about the time we expect enough gas to be produced.

After completing the walls, we shoveled the sand back into the hole and formed a dome.  The sand dome acts as a cast for the concrete dome to be poured over.

With the help of a small community army, several batches of extra strong concrete were mixed and poured over the sand cast.  For having never constructed such a thing, Kavili our builder did an amazing job of smoothing the concrete and ensuring that it was at the correct thickness.

The dome had to set for 5 days while in the meantime the outlet tank (foreground) and the inlet tank (background) were constructed.

After the dome was set came the most difficult part of the build - removing all the sand from underneath.  We shoveled the sand for the third time but this time it had to pass through a small hole just big enough for a person to pass.  It was sweltering under the dome and it took us all day to remove the sand.

The completed system.  After several layers of plaster inside the dome and the piping connected, the dome was covered with sand for insulation.  A cover was made for the outlet tank and an additional tank was constructed for producing compost.  The slurry that is pushed out of the digester will be transferred to the end tank where it will be mixed with grass and other material.

The builders, Anna, and I happy to be finished.  However, with our wee pile of poop, it remains to be seen as to whether or not all of our hard work and effort will pay off.