Aufarbeitung von Gärresten aus industriellen Biogasanlagen Versuche zur mechanischen Fest-Flüssig-Trennung

Translated title of the contribution: Processing of manure from industrial biogas plants mechanical solid-liquid-separation

Matthias Fink

Research output: ThesisMaster's Thesis

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The processing and disposal of digestate is of great importance for operators of industrial biogas plants due to the fact that huge amounts of digestate are generated causing high operating costs. A possibility to reduce the disposal costs is the total processing of digestates which generates dischargeable water and concentrated fertilizer. The first step of this process is solid-liquid-separation, which can be optimized by using flocculation and chemical precipitation processes. The focus of this master thesis is the investigation of the solid-liquid-separation performance of flocculated and coagulated digestate in the laboratory. The objective is to reach the lowest possible dry matter contents in the liquid phase to ensure the feasibility of the subsequent process steps. The specimen are taken from three different bio gas plants utilising mainly slaughterhouse waste, bio waste and food/kitchen residues and a mixture of bio waste, fat and food/kitchen residues. For the experiments polyacrylamide flocculants, non- polyacrylamide flocculants and polyaluminium chloride are used. The results show that it is possible to flocculate digestates by using a high concentration of flocculants. Sedimentation experiments reveal, that flocculated digestate shows no or only slow sedimentation behavior. Filtration performance of flocculated digestate is not predictable and the separation is not successful. Tests with a laboratory centrifuge show, that although most of the solid fraction can be separated, but the dry matter content cannot be decreased to under 0.6%. The reason for this might be that digestate components are dissolved in the liquid phase of the manure and cannot be effectively removed by flocculants or the solid-liquid-separation process itself.
Translated title of the contributionProcessing of manure from industrial biogas plants mechanical solid-liquid-separation
Original languageGerman
  • Ernst, Martin, Supervisor (external), External person
  • Ellersdorfer, Markus, Co-Supervisor (internal)
  • Lehner, Markus, Supervisor (internal)
Award date27 Mar 2015
Publication statusPublished - 2015

Bibliographical note

embargoed until 17-02-2020


  • biogas
  • processing
  • polymer flocculant
  • flocculation
  • manure
  • digestate

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