Factors Influencing Energy Generation from Municipal Sludge Digestion

Abstract

Renewable energy and carbon reduction targets are generating a great deal of interest in the production of a methane-enriched biogas from anaerobic digestion. Currently, the Water Industry generates the majority of this biogas using infrastructure which was not designed for either, energy generation or carbon footprint reduction. This paper highlights the results of a model which predicts potential renewable energy generation from sewage sludge based on a number of variables. Sludge type was f the most influential parameter of those tested with primary sludge generating over twice the energy of secondary sludge. As type and quantity of sludge produced is fundamentally influenced by wastewater treatment it is suggested that they be looked at in combination in order to maximise synergism. Pretreatment technology and highly efficient CHP engines were next most beneficial.
Additionally, biogas diversion from CHP (to grid for example) should be limited to
approximately 20% to avoid requirement of auxiliary fuel.

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