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Crust Removal

The formation of crust and various floating layers comprised of unfermented substrate is a common operational problem for many biogas plants. The problem is not limited just to primary fermenters but can often occur in secondary fermenters or digestate storage tanks. Crust and floating layers are formed in many cases, starting with the substrate quality change (e.g. from the new harvest), experimenting with new types of substrates, through disorders and shutdowns of stirrers, or as a consequence of a system breakdown (e.g. various failures of measuring and control sensors).

Crust and floating layers significantly increase the viscosity of the fermenters and digestate storage tanks contents. It may lead to a complete solidification of the fermenters contents which enables the operation of the biogas plant.

In practice, there are only three ways to solve this problem: 1) dissolution by water, 2) mechanical removal, 3) biological dissolution

The first two methods are in principle always associated with the shutdown of parts of the technology and the significant drop in electricity production. Following our professional focus, we specialize in the method of biological dissolution of the crust and floating layers because it is the only method that allows solving the problem without shutdown of the affected fermenter.

The dissolution of the crust runs very efficiently thanks to the use of active hydrolysis products that are applied in combinations and doses calculated directly for the individual needs of a particular case.

NovaEnergo method of the crust removal brings these benefits

  • The whole material of the crust is subsequently converted to biogas
  • There is no need to shutdown the fermenters and start them up again
  • Problem solved in short time without electricity production shutdown
  • Lower total cost of liquidation of the system breakdown

Selected references

Biogas plant Turá Lúka, Slovakia

  • BGP 1.0 MW
  • Primary fermenter volume of 4,000 m3; fermentation temperature 40 °C
  • The crust thickness of 1 m, consisting of unfermented maize and grass silage
  • The total time of dissolution of the crust: 2 weeks

Biogas plant Opava - Kylešovice, Czech Republic

  • BGP 550 kW
  • Secondary fermenter volume of 2,700 m3; fermentation temperature 43 °C
  • The crust thickness of 2-3 m, consisting entirely of unfermented straw
  • The total time of dissolution of the crust: 4 weeks

All references here

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150 00 Praha 5

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