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

Teil 3 Seite 8-35
one often tries to achieve a purification degree at which the cleaned wastewater resem-
bles municipal raw wastewater.
Anaerobic preliminary wastewater treatment
Because of the composition of the wastewater from the meat meal industry, this waste-
water should be very suitable for anaerobic pre-treatment. However, the elimination of the
nitrogen can not be achieved in anaerobic method. Furthermore, it is always possible to
achieve only part-elimination of the organic pollutant load, so that this can be used only for
preliminary wastewater treatment.
An anaerobic pre-treatment of the wastewater is eligible especially in case of indirect
discharged combined with a physical-chemical nitrogen elimination. In order to achieve
high volume-time exploitation degrees simultaneous with a high process stability, the ap-
plication of fixed bed reactors with wastewater recirculation has proved to be the most
efficient of the modern anaerobic technologies with biomass retention.
Table 8-4 shows the degradation rates of an installed anaerobic preliminary treatment.
Table 8-4: Influent and effluent data of an anaerobic pre-treatment plant
Parameter Influent Effluent
February July
In~/decreas
e
%
Influent
Effluent In~/decreas
e
pH 7,5 7,8 + 4 7,9 8,2 3,8
spec. conductivity
mS/c
m
6,67 6,89 + 3,2 7,54 7,66 + 1,6
Filterable solids mg/l 1.115 532 - 61,8 2.642 1.011 - 62
COD total mg/l 4.311 1.156 - 73,2 9.414 2.208 - 76,5
BOD5 total mg/l 3.433 534 - 84,5 5.890 1.154 - 80,4
Fat mg/l 370 90,8 - 75,5 717 265 - 63
NH4-N mg/l 126 145 + 15,1 185 208 + 12,4
org.-N mg/l 57,6 30,4 - 47,2 80,2 59,4 - 25,9
P total mg/l 8,7 8,6 - 0,7 14,5 12,8 - 12,1
Sulphide mg/l 24,1 8 - 66,8 8,1 13,5 + 65,2
Sulphate mg/l 39,5 11 - 72,2 65,5 22,8 - 65,2
Central biological wastewater treatment
Generally, for the central wastewater treatment with nitrogen elimination, the following
wastewater treatment methods are used for TBAs:
- single-stage activation methods with preliminary denitrification for additional wastewa-
ter treatment measures (such as pressure biology with large internal recirculation flow
for biomass concentration through membrane filtration),
- single-stage activation methods with simultaneous denitrification in undivided activa-
tion tanks,
- single-stage activation methods with alternating or intermittent denitrification,
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