Regulating feeding and increasing methane yield from co-digestion of C5 molasses and cattle manure

• Anaerobic co-digestion of C5 molasses with cattle manure at thermophilic (∼50 °C) and mesophilic (∼35 °C) condition.
• For meso co-digestion, max 28% methane boosting (yield 232 ± 32 L/kg VS) for a corresponding feed of 31–47% C5.
• For thermo co-digestion, maximum 28% methane boosting (yield 313 ± 16 L/kg VS) for a corresponding feed of 50–70% C5.
• VFA accumulation for both the digesters at the later period of the experiment which ended at day 69.

The paper investigated the mesophilic (∼35 °C) and thermophilic (∼50 °C) co-digestion of cattle manure and C5 molasses for a variable organic loading rate (OLR). The small scale continuous reactor experiment revealed that thermophilic treatment yielded a maximum 313 ± 16 L/kg VS methane for the feeding ranged between 50% and 70% C5 (v/v). Mesophilic co-digestion, on the other hand, produced maximum 232 ± 32 L/kg VS methane when feeding was ranged between 31% and 47% C5 (v/v). The feeding strategy of this study was sophistically adjusted owing to the unstable volatile fatty acids (VFA) pattern, developed at different stages of the experiment. Attainable molasses feeding for both the co-digesters was maximum 70% (v/v) above which the total VFA caused serious instability to the reactor performance in terms of methane formation. This phenomenon is suspected to lead to inhibition and hence caused the experiment to halt at day 69.