Co-digestion of biowaste and sewage sludge under meso- and thermophilic conditions: Comparison of biogas formation and composition

The number of applications for utilizing biogas for power production has grown significantly in recent years. An important factor relating to the economical profitability of biogas to electricity is to ensure good technical functionality. This has created significant concern about the presence of siloxanes and other trace components such as halogens and sulphur compounds in the gas. They cause damage such as fouling and corrosion in the biogas utilization equipment. The cost of converting biogas into electricity from municipal digesters and landfills can be adversely affected by these contaminants. This paper describes a method for on-line measurement of the total biogas matrix and presents the results of on site measurements of trace compounds in biogas and landfill gas at several sites in Finland. Furthermore it summarizes useable methods for siloxane abatement from biogas and gives an overview of the costs of biogas purification relating to electricity production applications. It will outline considered cases in detail where the economy of the installation and operation of siloxane removal equipment is compared to the costs of intensified service and repair of a biogas engine or turbine when using biogas containing selected concentrations of siloxane and sulphurous compounds.