Anaerobic digestion of wastewater from hydrothermal liquefaction of sewage sludge and combined wheat straw-manure.

Hydrothermal liquefaction (HTL) shows promise for converting wet biomass waste into biofuel, but the resulting high-strength process water (PW) requires treatment. This study explored enhancing energy recovery by anaerobic digestion using semi-batch reactors. Co-digesting manure with HTL-PW from wheat straw-manure co-HTL yielded methane (43-49% of the chemical oxygen demand, COD) at concentrations up to 17.

Biogas upgrading with hydrogenotrophic methanogenic biofilms.

Hydrogen produced from periodic excess of electrical energy may be added to biogas reactors where it is converted to CH that can be utilized in the existing energy grid. The major challenge with this technology is gas-to-liquid mass transfer limitation. The microbial conversions in reactors designed for hydrogenotrophic methanogenesis were studied with microsensors for H, pH, and CO.

Parameters affecting acetate concentrations during in-situ biological hydrogen methanation.

Surplus electricity may be supplied to anaerobic digesters as H gas to upgrade the CH content of biogas. Acetate accumulation has been observed following H injections, but the parameters determining the degree of acetate accumulation are not well understood. The pathways involved during H consumption and acetate kinetics were evaluated in continuous lab reactors and parallel batch C experiments.

In-situ biogas upgrading with pulse H additions: The relevance of methanogen adaption and inorganic carbon level.

Surplus electricity from fluctuating renewable power sources may be converted to CH via biomethanisation in anaerobic digesters. The reactor performance and response of methanogen population of mixed-culture reactors was assessed during pulsed H injections. Initial H uptake rates increased immediately and linearly during consecutive pulse H injections for all tested injection rates (0.