Sawdust

I’ve read sawdust gums up the works in digesters as it has too much fiber. I have a pair of working steers (term for young oxen in training up to 4 years of age) they weigh about 1000lbs each right now, they make a lot of manure. I have always wanted to make a methane digesters. The problem is I bed their barn in pine/spruce sawdust I get from a local clapboard mill. It’s smaller dust than the planer shavings type stuff you get at the feed store but not tiny like what you’d get off a table saw it’s more like what you’d get off a chainsaw. Anyway it’s always mixed in with the manure. Does this make it unusable? I was thinking perhaps if added with water and stirred up before pouring in the sawdust may mostly rise to the top and could be skimmed off, but I haven’t really experimented with this at all yet. I think making this “slurry” is part of the process anyway right? What about hay as a feed stock? The area around there hay feeder gets pretty thick with a mat of manure and wasted hay. Lots of stuff talks about grass clippings but I haven’t seen hay mentioned. Hay is really just dried grass clippings…

Hey Jeff.
What type of digester would you like to build/operate?
I think there are even digesters that can digest very coarse material with only very little moisture (more like an enclosed compost pile) as opposed to the ones that have a very liquid sludge in them.
Maybe there are some digesters that work with wooden material?

Just a standard wet style methane digester. Some sort of a large chamber probably with a floating drum style storage tank.

I envy the resources you have at hand!

I wonder, will it be necessary to stir the digester tank for best production? That's where the coarse material may cause problems. How do you plan to add fresh material and remove the sludge to keep production going?

I’m in the early planning stages now but plans can be found online for basic digesters I likely won’t reinvent the wheel I’ll just use someone’s proven idea and adapt it to the materials I have on hand. I do have a couple 500 gallon poly water tanks i am currently not using, I could salvage one of those for this project. You are correct some way to stir it is essential in most designs.