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The aim of study was to enhance the biogas production from cattle manure in a combined microbial electrolysis cell and anaerobic digestion system (MEC + AD). The MEC + AD reactor were operated on semi continuous mode under different voltage applications and different organic loading rates ranging from 6 g VS/L.d to 30 g VS/L.d. The study was carried out in two parts. In the first part, MEC + AD and conventional anaerobic reactors were compared in terms of biogas production. In the second part, MEC + AD reactor was operated under different voltage applications (0.3, 0.6, and 1.0 V) and organic loading rates. MEC + AD system exhibited 28–52% better biogas production performances (2.03 L/L/d; CH4:75.5% vs 1.43 L/L/d; CH4: 70.4%) compared to control reactor in all sets due to voltage application. In the second part, biogas productions of MEC + AD reactor changed between 3.08 L/L/d and 5.13 L/L/d (75–77.8% CH4) depending on the organic loading rates and applied voltages. Higher voltages (0.6 and 1.0 V) showed better methane production performances especially at high OLRs with respect to lower voltages. Consequently, MEC + AD reactor could be operated efficiently at extreme operational conditions (HRT of 2 days and OLR of 30 g VS/L/d) that conventional anaerobic reactors can not be operated.

In this study, single-stage and two-phase semi-continuous thermophilic anaerobic reactors fed with diluted (3 % total solids (TS) and 1.8 % volatile solids (VS)) chicken manure at three different hydraulic retention times (HRTs) were compared interms of biogas production rate, methane content of the produced biogas, and VS and TS removal. Along the study, HRTs of 16, 12, and 8 days were implemented to the single-stage and the two-phase systems. It was observed that the single-stage anaerobic system was superior to the two-phase anaerobic system according to their biogas production rates (517 vs. 356, 551 vs. 359, 459 vs. 386 (mL/g VS)) at all HRTs. On the other hand, methane content of the biogas produced was higher in the two-phase system compared to the single-stage system.

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