News - PFI Germany Fairs and Trade Shows

PFI Participates in Large-Scale
Research Project
Use of Enzymes in Biogas
Plants
Biogas plant operators are
repeatedly offered enzymes for
use in their fermenters. Vendors
claim that such enzyme preparations
accelerate the digestion
of plant-based biomass, reduce
floating layer formation, and
lower the energy consumption
of their stirring systems. However,
cost-benefit analyses for
these products have hitherto
only been performed in isolated
cases. In October 2010, together
with partners from science and
industry, PFI initiated a joint
project with the aim of elucidating
the effects of enzyme
preparations in biogas facilities.
Degradation of the structural plant
polymers cellulose and hemicellulose
in biogas fermenters typically proceeds
slowly and frequently also incompletely
in the case of high throughputs
and correspondingly short residence
times. Enzymes which hydrolyse
these polymers into their components
can thus exert a positive effect on
the rate and degree of degradation
of plant biomass. Moreover, plant
operators also hope that the use of
enzymes may have indirect effects of
process engineering relevance. Insufficient
degradation in biogas facilities
can often lead to the appearance of
N E W S L E T T E R
buoyant fibrous components which
form floating layers on the surface
and impair release of gas. In addition,
incomplete degradation of plant fibres
leads to increased dry-matter contents
and higher viscosities in the fermenter,
resulting in significantly greater energy
demands for stirring. Use of enzymes
is claimed to prevent or at least reduce
the formation of floating layers and reduce
viscosities. Whether these effects
are indeed achieved and whether the
sometimes substantial costs of enzyme
addition are justified remains largely
unclear. So far, only a few selected
enzymes have been tested, and not all
reaction mechanisms could be completely
clarified.
The joint project, which started on
October 1, 2010, will pursue these
studies in much greater depth. The
total of six research partners will investigate
the use of various enzymes and
enzyme mixtures on the anaerobic
fermentation of maize silage, solid pig
manure, maize/corn-cob mix, Sudan
grass, clover-grass mixes, and combinations
of these substrates. Importantly,
the research project is not limited
solely to laboratory studies. Instead,
the results will be checked first on a pilot
scale and then on a full sized plant.
The biotechnology department at PFI
will make a significant contribution
here. PEH technology (Process-controlled
Enzymatic Hydrolysis) developed
by PFI will be implemented in the
Neumann biogas facility at Wallhalben
near Pirmasens. Material and energy
balances will then be performed on
the basis of the resulting data in order
to arrive at a comprehensive economic
and process engineering assessment
of enzyme use. It should ultimately be
possible to provide biogas plant operators
with reliable guidance regarding
optimum enzyme mixtures and times
of addition.
The joint research project is scheduled
to run for three years and will be funded
by the German Federal Ministry of
Food, Agriculture and Consumer Protection
– through its project management
organisation the German Agency
of Renewable Resources (Fachagentur
Nachwachsende Rohstoffe e.V. – FNR)
– to the extent of Euro 1.7 m.
Further information:
Dipl.-Ing. (FH) Benjamin Pacan
Head of PFI Biotechnology
Tel.: +49 6331 2490 840
E-Mail:
benjamin.pacan@pfi-germany.de