298 94 307/02 Untersuchungen zum Stand der Umsetzung des ...

Teil 3 Seite 8-26
Generally, the plant consists of a preliminary unit where the exhaust air is conditioned
(spray cleaning, etc.) and the bio-filter as such (bio-bed).
The following table presents information on the emission data of TBAs with bio-filters:
Table 8-1: Data for the classification of odour reduction measures
Operation area Exhaust air
volume flow
Production 58.000
Odour concentration
in the raw gas
Odour concentration
in the clean gas
decrease
in percent
m³/h GE/m³ GE/m³ %
226
WWTP 1.430 159
Production 109.107 197
WWTP 3.939 160
Bio-bed 1 85.700 16.000 242 98,5
Bio-bed 2 75.800 21.500 236 98,9
Entire plant 16.000 60.000 35-100 99,8
8.2.3 Wastewater Treatment
One differentiates between the preliminary treatment of process water and of wastewa-
ter. The removal especially of the undissolved animal matter from the process water (fat
and fat particles, meat residues, hair, bristles, mineral admixtures) makes for a load de-
crease of the wastewater. The separated animal materials from the process water can be
conveyed back into the production process.
8.2.3.1 Mechanical methods
For the preliminary wastewater treatment, as a rule mechanical methods are used ini-
tially. Further preliminary treatment targets are the elimination of nitrogen compounds and
of hydrogen sulphide through physical-chemical methods, as well as the preliminary re-
duction of the organic pollutant load through biological methods. Not least, it may be nec-
essary to go for the neutralisation of the wastewater. For the wastewater pre-treatment, it
is also necessary to achieve an equalisation of the amounts and concentrations.
Through the installation of suitable cyclones or settlement chambers for the separation of
solid particles which have been dragged along before the condensators, precious sub-
stances can be recovered; moreover, an extensive reduction of the process water or the
wastewater after mixing can be achieved in this way. This will also protect the cyclones,
which must regularly be controlled. Emerging exhaust vapours should not exceed a tem-
perature of 30 °C when they are about to be discharged into the receiving waterway. If
need be, the temperature may be increased in a topped biological stage for the tempera-
ture regulation during the winter-time.
For the weekly equalisation and to equalise load peaks, meat meal companies usually
use mixing and equalisation tanks.