Biomethanation of Kitchen Waste and Sewage Sludge in Anaerobic Baffled Reactor

Biomethanation is a promising method for
transformation of organic fraction of municipal solid waste
(OFMSW) to valuable energy. In addition, as OFMSW has
considerable portion in any community generated solid waste,
biomethanation reduces the total waste to be collected,
transported and disposed to the landfill. In this study application
of laboratory-­scale anaerobic baffled reactor (ABR) for
production of methane gas through co-­digestion of kitchen waste
and sewage sludge was investigated. Performance of four ABRs
with identical volume of 75 l under hydraulic retention time
(HRT) of 3 days and with kitchen waste and sewage sludge mixed
at ratio of 100:0, 75:25, 50:50 and 25:75 was compared in terms
of methane yield and microorganisms growth. Results indicate
that, the ABR containing 75% kitchen waste and 25% sewage
sludge had highest volumetric percentage of methane (>80%).
This amount was relatively reasonable for other samples except sample with 100 % kitchen waste (< 20%). pH investigation shows sample containing 100% kitchen waste is slow comparedto the others in term of higher-­molecular-­mass compounds breakdown as well as development of both acid formers and methane formers. This signifies that not only the suitable substrate but also proper development of different species of microorganisms is vital in any biomethanation system.