DIY Biogas Digester (preamble)

Since the bands are kind of shit at the moment and I have grown tire of looking at static filled waterfalls, I decided to fill my time with a somewhat pointless, but mentally stimulating project (but aren't they all really). I have a couple of dogs and not a lot of space which means a lot of dog poop generation with few options to get rid of it. Winter is especially bad since the composters freeze and there is really sooo much dog shit piling up. This plus waste food production happens all winter and since I like to make things complicated, an insulated biogas digester was the obvious answer (who wouldn't agree with me?).

I have always wondered why more people and businesses don't have biogas digesters on premises. A bio digester is a simple device that is essentially a compost container without the air. It is a reactor devoid of oxygen that contains a slurry of organic waste and bacteria that turns that waste into some methane, other gases and digestate (waste nutrient rich slurry... for the garden you know?). The process needs the right organic feedstock to maintain pH, the right temperature to keep the process going and a ton of other process requirements. 

They are much more popular on a home scale in Africa and Asia and on a farm scale in Europe. In North America we haven't quite found a reason to use them (probably because we are all rich and fat). There is a dedicated community of DIYers though in NA that have lots of how to build digester videos on YouTube. Just take a quick search and you'll discover it is flooded with home built digesters. This is an example (not NA video, but I don't care).



Most of these don't work for cold climates though so this is yet another biogas producing digester how-to - cold climate styles. I was inspired by this design https://completebiogas.com/content/about-cube, but honestly way too lazy to build that crap so I'm improvising instead. I'm going to essentially build the digester shown below with insulation added. (I shamelessly ripped this image off of google search so if it is yours, let me know and I'll happily credit you).




I will have a permanent project page on my www.hamradioexperiments.com site that documents the entire device and posts ongoing monitoring data, but that's not up at the moment and will get there when I feel like it. Yes I will be instrumenting the device and yes I'll have some scrubbing of CO2, H2S etc... (something like this if you are interested in reading https://www.permselect.com/products) Damn straight that shit will have gas sensors too.

Let the journey of eliminating poop begin. 



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