Got the gas outlet installed last night. Hopefully the last time I have to take the main feed sump off, but I took some pics of the inside while I had it open to see what the feedstock is doing so far, in a semi-aerobic composting environment.
It actually doesn't smell very bad- a bit earthy. You can see a lot of it floats and has formed a pretty substantial scum cap on the water surface. This is about 1/3 full so there's lots of room for more feedstock and water can be added to keep the water seal intact. Float-y material is being pushed down the feed sump to below this cap and then floating up underneath it, by means of the sump extending below the surface and using a plunger to get the feedstock inserted. As long as it stays moist I imagine the methanogenic bacteria will continue to work on it. But I do see a benefit to a stirring mechanism (which I don't currently have.
I drilled a 1.25" diameter hole with the hole saw. That's just about the inside diameter of the threads on the bulkhead fitting. So it required a little clean-up and expansion to get the fitting through the hole, and the outside diamater of the threads didn't quite fit through.
The inside piece of the bulkhead adapter is reverse-threaded. Make sure you have a big enough wrench BEFORE you're stuck on top of your project reaching into the moist, smelly environment, and don't drop it into the goo.
Then it was a simple matter of putting in hose barb. I added an elbow so the soft clear tubing that will eventually be installed doesn't have to stand upright under its own support , since it will probably sag in warm weather and might cut off gas flow.
Next up is constructing my hydrogen sulfide filter and gas storage/delivery solution while the main tank 'cooks'. I still have lots of feedstock left to go in over time.