title: Optimizing the thermophilic hydrolysis of grass silage in a two-phase anaerobic digestion system.
abstract: Thermophilic hydrolysis of grass silage (GS) at 55 °C with organic loading rates (OLRs) of 6.5, 5, 2.5 and 1.0 kg VS m(-3) days(-1) and hydraulic retention times (HRT) of 10, 6, 4 and 2 days were evaluated in 12 glass bioreactors side by side. The hydrolytic process was measured by variation in pH, volatile solids (VS), VS destruction, soluble chemical oxygen demand (sCOD), hydrolysis and acidification yields. Biological methane potential (BMP) assays were carried out to measure the upper limit for methane production of grass silage with different hydrolytic pretreatments at mesophilic temperature (37 °C). The optimum methane yield of 368 LN CH4 kg(-1) VS was obtained at an OLR of 1 kg VS m(-3)days(-1) and a HRT of 4 days, showing an increase of 30% in the methane potential in comparison to non-hydrolysed GS.
authors.affiliation: Questor Centre, School of Chemistry and Chemical Engineering, Queen's University Belfast, Northern Ireland BT9 5AG, United Kingdom. aorozco01@qub.ac.uk
authors.forename: A M
authors.initials: AM
authors.lastname: Orozco
authors.forename: A S
authors.initials: AS
authors.lastname: Nizami
authors.forename: J D
authors.initials: JD
authors.lastname: Murphy
authors.forename: E
authors.initials: E
authors.lastname: Groom
mesh_terms: D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008697:Methane / Q000096:biosynthesis; D006109:Poaceae / Q000378:metabolism*
chemical_list: D008697:Methane
keywords: Anaerobic digestion; Biogas; Grass silage; Thermophilic hydrolysis; Two-phase anaerobic digestion