Why sometimes does my anaerobic digestion not produce gas?

I am running the single AD reactor 45 days. At the 23-32th and 44-45th day there was no gas production.  I use OLR 0.7 kg COD/m3/d. The average of alkalinity and VFA are 5000 mg/L and 140 mg/L in...

13 January 2017 8,821 18 View