Improved methane production of two-phase anaerobic digestion by cobalt: Efficiency and mechanism

Two-phase anaerobic digestion (AD) is a promising technology, but its performance is sensitive to methanogen. In this study, the effect of cobalt (Co) on two-phase AD was investigated and the enhanced mechanism was revealed. Though no obvious effect of Co2+ was observed in acidogenic phase, the activity of methanogens was significantly affected by Co2+ with an optimal Co2+ concentration of 2.0 mg/L. Ethylenediamine-N'-disuccinic acid (EDDS) was the most effective for improving Co bioavailability and increasing methane production. The role of Co-EDDS in improving methanogenic phase was also verified by operating three reactors for two months. The Co-EDDS supplement increased the level of Vitamin B12 (VB12) and coenzyme F420, and enriched Methanofollis and Methanosarcina, thereby successfully improving methane production and accelerating reactor recovery from ammonium and acid wastewater treatment. This study provides a promising approach to improve the efficiency and stability of anaerobic digester.

Automated summary

This study investigated the effect of cobalt (Co) on two-phase anaerobic digestion (AD) and revealed the enhanced mechanism. The activity of methanogens was significantly affected by Co2+, with an optimal concentration of 2.0 mg/L. Ethylenediamine-N'-disuccinic acid (EDDS) was found to be the most effective in improving Co bioavailability and increasing methane production. By supplementing with Co-EDDS, the levels of Vitamin B12 (VB12) and coenzyme F420 increased, leading to the enrichment of Methanofollis and Methanosarcina and successfully improving methane production and recovery from ammonium and acid wastewater treatment.