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

Teil 3 Seite 7-5
- Cleaning wastewater of the clean side, with a considerably lower load than that of the
unclean side. With this part-stream, we find again that it does not increase proportion-
ately with the size of the plant.
- Wastewater from the exhaust air treatment, which is comprised of the wastewater from
the process exhaust air and the room exhaust air. The treatment can be done together
or separately. The wastewater from the process exhaust air treatment can be highly
loaded with organic components (up to 25.000 mg/l COD), Merkaptanes (up to approx.
2.000 mg/l, hydrogen sulphide (up to approx. 800 mg/l), ammonium nitrogen (up to
approx. 400 mg/l), ethereal oils, phenoles, aldehydes, etc. Because of the low waste-
water production, however, only low loads can be expected.
- Wastewater from the lorry cleaning, which may contain mineral oil and high ratios of
solids, possibly also cleaning agents.
- Wastewater from the production water processing, which is produced during the re-
generation as neutral saline solution.
- De-sludging wastewater from the evaporators, which is has hardly any organic load,
but which may contain higher concentrations of phosphorous compounds from the
conditioning agents. This part-stream has particularly high pH-values, which must be
taken care of.
- Wastewater from the de-sludging of the cooling water recirculation
- Cooling water from the continuous-flow cooling
- Domestic wastewater, which additionally contains laundry water, so that principally for
-
each member of the staff the full population equivalent is assumed
Wastewater from fortified areas with a lower load.
According to Table 1, the specific entire raw wastewater production is 0,9–1,6 m 3 /t of
raw material. The average specific raw wastewater production can be assumed to be 1,1
m 3 /t of raw material. The larger the respective plant, the lower is the specific wastewater
production, because particularly the cleaning wastewater amounts do not correlated with
the size of the plant.
In the majority of plants, there is not production at the weekends, so that then no waste-
water is produced. Thus, in this industry wastewater equalisation is used.
The pollutant concentrations and loads are mainly caused by the process water from
sterilisation and drying, so that also for the entire production wastewater there results a
dependence on the kind and condition of the raw material and thus also on the outside
temperatures (summer and winter values). As the process water, the entire production
wastewater has a high load of organic substances and reduced nitrogen compounds.
Phosphorous is contained in higher concentrations only when the entire wastewater con-
tains also process water from the blood processing. Otherwise, there is a shortage of
phosphorous. The composition of the raw wastewater from TBAs (without processing of
blood, feathers, and bones) is presented in the following table.