A process for the generation of power is disclosed. The process comprises receiving a wastewater stream containing organic matter and passing the wastewater stream to an anaerobic digester in which the organic matter contained therein is broken down to produce biogas. The liquid content of said wastewater stream is reduced before said stream enters the anaerobic digester by passing the wastewater stream through an osmotic power unit. The said stream is passed over one side of a semi-permeable membrane which permits the passage of water but not the passage of salts, an aqueous stream of higher salinity than said wastewater stream being passed over the other side of said membrane such that latent osmotic energy present in said aqueous stream of higher salinity is converted into electricity.