The present work presents some of the results of five reports developed in the scope of optimization feasibility studies carried out at 6 small- and medium-sized wastewater treatment plants (WWTP) in Portugal. These 6 WWTP are operated by five companies that belong to the Águas de Portugal holding. The objective of the studies was twofold: to
assess to which extent the production of biogas could be increased by means of
operational modifications and/or by the implementation of co-digestion regimes; and also
to simulate different scenarios for feed-in tariff of electricity taking in account energy
prices calculated based upon the DL n.º 225/2007 of 11th May. In this way, several codigestion
scenarios were defined based upon standard available organic residues. The
results obtained showed that the implementation of co-digestion regimes represent a
significative potential to increase the production of biogas, in some cases, over 600%.
Even though, it was concluded that in some cases the costs of introducing new regimes
of energy management were not supported by the increase of energy production, so a
scale factor is associated to the revenues. This study contributed to the establishment of
specific needs in terms of information management (digester operation, energy
production/consumption, strategy for optimisation)
