Not really a way to produce biogas, but certainly a kind of bioreactor, an aerobic treatment system uses aerobic bacteria to process waterborne waste.
To do so , oxygen is introduced usually by an air pump.
This process is usually used to remediate human feces , but what if it were used with food and yard waste, or animal waste, kind of like the feedstock anaerobic bioreactors use?
I'm imagining a slurry of waste replacing the molasses usually used in making aerobic compost tea.
The brewing goes on longer because the aerobic bacteria actually have to work at breaking down this meal.
This would be a forced air composting system, using water to facilitate the grinding and turning of the materials.