Patent DE-102007036049-A1 (DE)
Title: Fermentation of pourable, cuttable, stackable/fluid biomass e.g. grass cuttings for biogas production, comprises pretreating and then fermenting the biomass in reusable, gas-tight fermenter up to complete or to large extent mineralization
Inventor: FUS ANDREAS
IPC: C12P5/02
Filed: 2007-08-01
Abstract: The method for the fermentation of pourable, cuttable, stackable or fluid biomass e.g. grass cuttings for biogas production, comprises pretreating and then fermenting the biomass in a reusable, gas-tight fermenter (1) up to a complete or to a large extent mineralization, and removing the biomass from the fermenter to refill new biomass. The pretreatment and inoculation of the biomass are optionally carried out. The pretreatment includes addition of water, sanitization, homogenization, grinding or dehydration. The biomass is inoculated before, during or after filling with inoculation material. The method for the fermentation of pourable, cuttable, stackable or fluid biomass e.g. grass cuttings for biogas production, comprises pretreating and then fermenting the biomass in a reusable, gas-tight fermenter (1) up to a complete or to a large extent mineralization, and removing the fermented biomass from the fermenter to refill new biomass. The pretreatment and inoculation of the biomass are optionally carried out. The pretreatment includes addition of water, sanitization, homogenization, grinding or dehydration. The biomass is inoculated before, during or after filling with fluid or non-fluid inoculation material. The inoculation materials are: thermophile and mesophile; thermophile and psychrophile; psychrophile and mesophile; or thermophile, mesophile and psychrophile. The inoculation of the biomass takes place with two different inoculation materials in such a manner that the inoculation materials are introduced after filling the fermenter, at which the conditions suitable for the microorganisms are controlled. The biomass is displaced with additives before, during or after bringing into the fermenter. The additives affect the fermentation of the biomass with nutrients and/or ferments for the microorganisms involved in the fermentation, buffer substrate for the pH value adjustment or water for adjustment a desired solid content. The inoculation of the individual loads partially takes place after filling of fermenting substrate or percolate by container-internal circulation. The fermenter is filled in charge-wise manner and further loads are added before the loads are fermented completely, or is continuously filled, where the continuous filling takes place as the biomass present in the fermenter is reduced, so that the filling takes place without discharge of biomass from the fermenter. The resulting biomasses are sorted in such a way that only biomasses suitable for a common fermentation arrive into a common fermenter or are mixed so that easily fermentable material arrives together with hard fermentable materials into the fermenter. The biomasses of same kind or same origin are fermented in the common fermenter. The pre-formed product e.g. biogas is sucked off before charge-wise filling of the fermenter. Infiltrated air is removed from the fermenter after the charge-wise filling with biomass in order to provide anaerobic conditions, where the removal of air takes place via draining or displacement through other gases and/or gas mixtures. After charge-wise filling with biomass, an aerobic pre-fermentation phase (acid formation phase) is produced, in that air infiltrated during filling in the fermenter is discharged, or additional air or oxygen is added. The aerobic pre-fermentation phase is extended by repeating three to five times sucking off and renewed ventilating. After the aerobic pre-fermentation phase, gas mixture consisting of oxygen-less and/or oxygen-free and variable product e.g. biogas is removed, before the product formation is strengthened and/or before the collection of product is begun. The biomass is mechanically compressed before beginning the fermentation. The water is added to the biomass in order to prevent spontaneous heating and -ignition or to reach a desired dry substance portion. The fermenter is provided with a drainage device to collect the resulting percolate. The biomass is separated into liquid phases and solid phase during the fermentation. The collected liquid is removed from the fermenter, while the solid portions remain in the fermenter. The separation of the substrates into the fluid- and the solid phase is reached and the substrate present in the plant acts as filter mass, by which the liquid portions are passed through and removed, while the solid portions remain in the fermenter. A small negative pressure or same absolute pressure as outside of the fermenter is constantly maintained by suitable devices. The process is carried out manually or automatically with computer or microprocessor under analysis of suitable sensor signals. An independent claim is included for a device for the fermentation of pourable, cuttable, stackable or fluid biomass.