balance tank included.
The second dome, counted from from the feeder, also serves as a balance tank since it is communicating with the elevated overflow. Since the design is for an urban situation, the overflow continues into a small city sewer. Instead of the city sewer you can alo make a large sub-soil surface collection tank from which you can collect the effluent for processing as fertilizer. In the particular design the urine was collected separately and also has to be collected from a sub-soil tank.

Thanks for the clarification in regards to the air intake.
Not sure about using the "play-pump" approach to stirring bio-digesters...

JKMakowka -

The anaerobic digestion has two phases - acid formation and methane formation. The first phase produce acid and lower pH, while the second phase consume acid and raise pH. Unfortunately the bugs like neutral pH to be happy, and these two phases work together to keep the pH neutral. So if you split them into two different phases, they will not work. This splitted "two-phase" has been tried 30 years ago and some people are still trying .... sorry you are not the first one .

sjoerdnienhuys -

Your process is essentially a two-stage process, with the first stage being used to handle raw influent and the second stage to handle that from the first stage. Yes - this will improve gas production. The mixing might work, but they are pretty mild. I wonder if this biogas gain is worth the effort due to the more complexed design.

Jianmin

For those of you wanting to learn a bit more about Jianmin's research, I can recommend watching this online discussion that we recorded with Jianmin on 1 July.
His explanation about his project (without a powerpoint) starts at 15:29 into the recording; it is followed by questions and answers that start at around 22:55 until 28:44.

I have added the Youtube link below to start at exactly the right time:



In the question session, the following was discussed:

Arno asked if farm-based reactors in China could be retrofitted with this mixing device. Jianmin explained that this is not really possible because his mixing device works best with a taller reactor, not with a flat one. He explained that the main purpose of the mixing is to prevent sludge deposition at the bottom and to break up floating sludge.
Jianmin proposed that his biogas reactors would be smaller and could be built at a centralised location (factory) to minimise the problem of leakage that often occurs with locally-made digesters.

Toni asked Jianmin if his system is not very similar to existing European mixing systems for digesters, in particular these two:
Dranco: www.ows.be/household_waste/dranco/
and:
Valorga: www.valorgainternational.fr/fr/

Jianmin wasn't able to answer this question because he didn't know those particular companies, although he felt that mixing by collecting gas in the middle of the tall reactor is the novel aspect.

Gabrielle asked about the % increase in biogas production: Jianmin said it is about 30% increase in biogas production with his mixing system. He thinks that more increase would be possible with taller reactors, and hopes to be able to research this in the future if he gets more research funds.

Thank you, Jianmin, for your participation in this! (and please correct me if I noted anything done incorrectly)