Reviewing the Orange Digestor Design

  

Looking Back at what the Seniors had done:

1. Is the System truly anaerobic?
2. Is the ATAD Process really auto-thermal?

The on-site orange digestor:

The Orange Digestor PFD:

To investigate the anaerobic design claims, we started off with some line tracing:

1. We found that the vent at the top of the anaerobic stage has no isolation valve
   
   
2. The carbon filter basically acts as an adsorption column - An adsorption device does not function like a check valve.
   
   
3. However, given that the digestor's pressure is greater than atm pressure, air can only exit. Hence, no oxygen can enter the system. This, in a sense, makes the system anaerobic
   
   
4. To ensure that the system is 100% anaerobic, the next batch should discuss with Dr Han to design an isolation valve, together with a methane capture system.

To investigate the auto-thermal claims, we connected a data-logger to the Aerobic stage RTD: 

Temperature Readings for the 2-week anaerobic digestion were as follows:

 

As observed from the above plot, sludge temperature stayed in the region of 30 Deg C.

Auto-thermal Process? My foot Mr Kon !! A heater would really be needed to optimize the digestion process and to maximize methane output.

Kian How, signing off on 12/12/10 at 4.15pm.