Luostarinen et al. (2009)reported similar results during SS codigestion with grease trap sludge from a meat processing plant.
When grease trap sludge was increased from 46% to 58% of the feed
VS, the methane yield did not increase, but no signs of inhibition
were observed. Similarly,Luste and Luostarinen (2010)reported
a stable anaerobic co-digestion of SS with a mixture of animal
by-products when the HRT was decreased from 25–14 days, but
the highest methane yield was reported with an HRT of 20 days.
This reinforces the hypothesis that under these conditions, the
degradation kinetics of LCFAs is the rate-limiting stage, and inhibition phenomena are not relevant.