title: Initiating methanogenesis of vegetable waste at low inoculum-to-substrate ratio: importance of spatial separation.
abstract: With the goal of starting-up the methanogenesis of easily biodegradable waste with minimum inoculum, the present work evaluated different inoculum-to-substrate ratios (r(I/S)) in completely mixed systems and in the systems with spatial separation of inoculum and waste. It was found difficult to initiate methanogenesis in the completely mixed systems, even at high r(I/S) 1.105 on a volatile solid basis. Fermentation efficiencies were independent of r(I/S). In the spatial-separation systems with a low total r(I/S) 0.053, the ultimate methane yield (35 °C, 1 atm) reached 445 mL/g-VS added for the inoculum-waste initially completely separated system. The yields decreased to 285, 181, and 34 mL/g-VS added, respectively, for partially separated systems with the ratios controlled at 1.105, 0.254, and 0.113 in the inoculum-containing reactors. This demonstrates the importance of setting spatial separation between inoculum and waste when inoculation is employed. An appropriate inoculation method would initiate methanogenesis rapidly even at low inoculum-to-substrate ratios.
authors.affiliation: Institute of Waste Treatment and Reclamation, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China.
authors.forename: Fan
authors.initials: F
authors.lastname: Lü
authors.forename: Liping
authors.initials: L
authors.lastname: Hao
authors.forename: Min
authors.initials: M
authors.lastname: Zhu
authors.forename: Liming
authors.initials: L
authors.lastname: Shao
authors.forename: Pinjing
authors.initials: P
authors.lastname: He
mesh_terms: D000143:Acids / Q000737:chemistry; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D056804:Biofuels; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods*; D002244:Carbon / Q000737:chemistry; D004867:Equipment Design; D005285:Fermentation; D008697:Methane / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D012722:Sewage; D013696:Temperature; D013997:Time Factors; D014675:Vegetables
chemical_list: D000143:Acids; D056804:Biofuels; D009930:Organic Chemicals; D012722:Sewage; D002244:Carbon; D008697:Methane