Anaerobic Digestion Plant

PAL Green Division was awarded the bid to develop an anaerobic digestion plant in the province of Lecco, in Annone Brianza, for the client Silea S.p.A., an wholly-public waste management company operating in a territory boasting the highest and most efficient levels of sorted waste in Italy.

The proposed technology involves the installation of 2 anaerobic digestion modules, each being 28 x 7 x 7 m (L x D x H) in size for the treatment of 31,000 t/year OFMSW, without adding any green fraction in the reactors.

The anaerobic digesters are of the dry type and use the plug-flow system with a biomass permanence time of approximately 21 days. The biomass fed to the reactors appears as a highly viscous and perfectly homogenous sludge, this homogeneity reducing the risk of sedimentation because the solids in the material are subject to a high drag force that is able to counteract the force of gravity. The elimination of inert material or at least its fragmentation into small pieces, either of low specific weight or higher specific weight, from the biomass fed to the digesters results in a feed consisting only of completely putrescible material and thus producing biogas, which significantly increases process yields.

The Upgrading system consists of a scrubber tower for H2S removal with a subsequent filtration system, a biogas first compression section, a membrane upgrading section, a second compression section and, finally, a unit for analysing and measuring the biomethane before feeding it into the grid.

PAL Green Division is the ideal and most reliable partner for the anaerobic digestion plants thanks to the great experience on the engineering and the construction developed in this important and strategic sector.