Here are the original diagrams that Chris, Vic, and Harley came up with when they wanted to build an agitation system for the prototype batch digesters at the UBC Energy Farm. This system is designed to mix the substrate and break-up the hard layer of scum that forms on top of the digestion slurry. To understand the process better, I allowed scum to form on top of a specific anaerobic bacteria culture I was observing. I noticed that bubbles do form but are trapped under the thin scum layer- like a small balloon. We don’t want this to occur during large scale production, and so we have made some modifications to the typical batch digester design.

Biogas Agitation Original Diagram

Bearing Orientation Diagram

Typical Small Scale Batch-Style Digester with 55 Gallon Oil Drum