Biogas project Update
In the May Biogas course, we built some pillars in the biodigester with leftover bricks, on which plywood was placed, cut to size to fit perfectly the diameter of the pit. This would then support soil to form the base on which to pour concrete for the dome.
Building the bricks to rest the plywood base onto to build the soil dome for the biodigester.
Tom, students and helpers ensured the plywood was stable and then they proceeded to pile soil on top of it, keeping it slightly wet and shaping it as a dome. On top of the soil, sand was patted down so the cement wouldn’t stick to it. Once that was done, they mixed the cement and gently shaped and padded the cement in place, smoothing it out as they went. A good 10 days of cool and damp weather was perfect to cure the concrete without cracks. On the top of the dome Tom needed to build a brick tower to house the gas pipe, which he did after the concrete dome had set.
Starting to put soil on top of the ply base
Soil is whetted down and shaped as a dome
The dome exterior is covered with sand to stop cement sticking to the soil, note the gas pipe sticking out.
Bit by bit concrete is poured and worked on top of the soil dome. It is a slow and laborious process to ensure the concrete stays smooth all around.
The finished cement dome for the roof of the biogas biodigester
Once the cement had dried, Tom had to remove the plywood to drop the soil into the pit, and shovel it out of the confined space. This took most of one day (and a lot of sweat!!).
The next stage of the biodigester is building the inlet and outlet, and if time permits starting on the toilet which will feed into the biodigester as well. This will be done as part of the next biogas course and runs from 19 to 23 August. Please email info (at) permeco.org for more information or to book.
Author: Zaia Kendall
Zaia grew up in a family of musicians in Holland, and has a background in top sport (snow skiing) and web development and design. She co-founded the PRI Luganville and PRI Sunshine Coast Inc (now PermEco Inc.) with Tom, and runs the “invisible structures”, like finances, business administration, website design and maintenance, writes articles and records and edits videos. She assists Tom in running the Kendall Permaculture Farm and supervising other volunteers. She is an active member of several musical projects and bands, involved in community music and runs percussion and marimba workshops, is the percussion leader for the Woodford Folk Festival People’s Orchestra and composes as well as plays music. She is passionate about community music and loves seeing people discover that they can play!
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Have you produced a how to DVD for this?
No Patrick, unfortunately not, but we will attempt to get all documentation together and publish it. Time, as usual is an issue for us in these things…
Do you have the plans available?
Or Can you connect me with Bill Mullison who gave you the Biogas plan?
Or is there someone else you recommend who has plans?
Lastly, I live in varied temperatures: 100+ in summer and 30/40 below in winter (farenheit)
Any suggestions for the biogas system?
Do you use it for heating anything else such as water etc.?
Hi Ethelyn, here is the link to the plans that I used.
http://www.build-a-biogas-plant.com/PDF/Afghan_Biogas_Construction_Manual_2011.pdf
There is more information in the manual that will help you with understanding the process .
I hope these help. Let me know how you go.