| abstract |
The multistage anaerobic treatment for biomass, with simultaneous recovery of biogas, comprises mechanically separating contaminants followed by a preliminary stage of mechanical breakdown; mechanically disrupting the cells by ultrasound before and/or after later stages; microbiologically pre-hydrolysing; and mechanically conditioning and hydrolysing, with separate treatment of sedimented solid material and floating light material. Heating and conditioning with pH adjustment are followed by methanisation (i.e. digestion), the sedimented solids being treated separately. The mechanically separated digestion residues are composted aerobically, with process water treatment. Also claimed is a plant for the above process, in which the hydrolysis and methanisation reactor is rectangular with the base sloping, and has a sludge extraction screw over the length of the sump. |