Effect of biochar on reactor performance and methane generation during the anaerobic digestion of food waste treatment at long-run operations.

• The AD of FW treatment improved with different biochars was studied. • Biochar significantly increased maximum production rates of biomethanation. • LBC was slightly superior to CBC at OLR of 6.0 gVS^/L⁻d. • Methanothrix was the predominant methanogen in R1 and R2. Anaerobic digestion (AD) is a green technology that is widely applied to food waste (FW) treatment. It can harness resources from the FW and mitigate associated environmental pollution and sanitation related problems. Despite the AD high efficacy, at high organic loading rate and long-run time operations, low methane yield, and reactor instability often occurred. To overcome such associated problems and improve efficiency at a high organic loading rate (OLR) of 6.0 gVS/L⁻d and long-run operations of 350 days. The performance of different biochar as additives with food waste treatment in the AD was investigated. Both the local biochar (LBC) and commercial biochar (CBC) shows similar efficiency that enhanced high methane yield (5%) compared to the control. The further outcome from laboratory study revealed that biochar had significantly influenced alleviation of Ammonium–N concentrations above 2450 mg/L with bio-degradation of VFAs, thus stimulating reactor process stability and performance. Methanothrix was the most abundance methanogens in the biochar amended reactors, it out-strived Methanosarcina by the higher growth rate and tolerance against inhibition on long-run operations. Overall, the biochars had a positive effect on the digester stability at high OLR and promoted bio-methanation during the long run operations. [ABSTRACT FROM AUTHOR]