- Take over
station
Take over procedure is the same as described before. In addition,
there is the possibil-ity to take over liquid wastes like fats,
restaurant garbage and residues from indus-trial processes and
slaughter houses which are stored in separate tanks.
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- Pre-crushing
Pre-crushing is necessary only to open plastic bags and other
packing. It is done by a slow running screw mill producing a
particle size of approx. 40 mm. The final milling and homogen-isation
takes place in the next step. Since pre-separated garbage is
delivered, the separation is done automatically. The screw mill
is placed on top of the suspending unit and is fed with the bio
waste by a crane.
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- Homogenisation,
Suspension, and Separation
This is done in one single stage by means of a special suspending
unit consisting of a steel tank with a built in mixer. The pre-crushed
material is fed from the top and di-luted with the process water
up to a dry matter content of about 10 %. During the di-luting
process the pre-crushed material is intensively mixed and suspended.
In order to achieve better solu-bility of fats and proteins and
for hygienisation purposes, the suspension is heated up to about
70 °C. Due to the intensive movement of the liquid, small
plastic particles, wood, and paper are separated from adhesive
fats etc. and float. The floating fraction is removed from the
surface by an especially designed screen and conveyed to a container.
Glass and metals are separated from the liquid by sedimentation.
They are removed from the bottom of the tank and gahered in a
separated container.
As a result, a homogeneous suspension of water and organic material
is created which is free of foreign matters. This suspension
with a dry-matter-content of about 10% is pumped to a buffer
tank to allow a constant feeding of the rector over 24 h/d. From
the buffer tank the suspension can be either pumped directly
into the methane reactor or mixed with other liquid wastes prior
to fermentation.
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