Biogas production from presorted biowaste and municipal solid waste from Sweden : substrate characterization, wet fermentation and cash flow analysis

Abstract

Due to the great demand of methane as car fuel by the local population in the state of Västmanland, Sweden, a Swedish company called Svensk Växtkraft AB needs to the triple the biogas production until year 2016. A problem is the availability of biowaste, which is nearly completed utilized in the biogas plant already. To solve this problem, the utilization of presorted municipal solid waste (MSW) is an option.

This thesis is aiming at characterization of pre-sorted biowaste and municipal solid waste regarding their utilization for biogas production by continuous mesospheric wet digester as well as mesophilic and thermophilic batch reactors. Biogas production for pre-sorted biowaste and municipal solid waste was investigating in the laboratory via self-constructed continuous reactors and at the same time, batch tests were carrying through for measuring the biogas potential of the wastes mentioned above, as well as the reject waste sorted out from existing biogas plant, at 40ºC and 55ºC. The biogas production results of municipal solid waste by mesophilic wet digester should be compared with the results of the same waste by mesophilic wet digester with enzyme addition, thermophilic dry garage fermenter and thermophilic plug flow fermenter. Besides, cash flow analysis for the company Svensk Växtkraft AB is also investigated in this thesis to find out the factors that affects the cash flow of the company.

The results indicated that biowaste and municipal solid waste are able to produce biogas consists of high methane concentration values, which is perfect for biogas quality. High reinvestment cost is the main factor that affects the cash flow of Svensk Växtkraft AB.