Trace elements (TE) application increase methane (CH4) yield by improving anaerobic digestion (AD) performance; one of the most important TE is nickel (Ni) since it has an essential role in well-performing methanogenesis. Digestates from the dark fermentation (DF) process are still rich in nutrients and organic matter, allowing them to be used to generate CH4 in a second stage. The main objective of this research was to evaluate the yield and productivity of CH4 and remove organic matter from 3 digestates of the DF process of organic solid waste (OSW) enriched with Ni2+. Three different digestates Ni2+ enriched, were used. An anaerobic sequencing batch reactor (ASBR) was operated with a pH of 7.6 and a temperature of 37 °C. The biogas composition (CH4 and CO2) and volatile fatty acids (VFA) were carried out by gas chromatography. The highest CH4 productivity and yield were obtained using the digestate with the lowest content of Ni (681 mL CH4/L/d and 566 mL CH4/gVS added, respectively). The VFA removal was higher than 97% in all the cases. It was concluded that nickel in DF influences the generation of medium-chain fatty acids, the production of CH4, and the removal of chemical oxygen demand and volatile solids.

https://zoom.us/j/95479629486?pwd=MWV0S1FRaTZ3RUJpSW9RZW9vSGh1dz09