Emissions to water
Water that is taken in has to be treated before it is used in the process, and it is again treated after the process before it is released as effluent to a recipient. The substances in the effluent after wastewater treatment are reported.
All mills have some sort of effluent water treatment, either mechanical treatment by sedimentation or in addition biological anaerobic and aerobic or chemical treatment of the effluent.
A few mills send their effluent water to an external communal treatment plant.
The volume of effluent water is reported separately for process water after treatment and non polluted (including thermally polluted effluent, e.g. cooling water). All mills have reported the figures for outgoing effluent water to the recipient i.e. effluent water after final treatment.
The amount of substances (COD, BOD, suspended solids) per m3 of effluent from the different mills show very little variation when the efficiency of the waste water treatment station is the same. The amount of substances per tonne paper production may however vary according to the amount of effluent, depending on specific circumstances in the paper production process in the different mills.
In the questionnaire for data collection, a number of other emissions were asked for like oils, nitrates, acids, AOX, chlorate, chlorides, borates, phenol, Hg, Pb etc. Few mills were able to report figures, probably because there are no or few measurements. Only COD, BOD5, suspended solids, total nitrogen and total phosphorus are based on data from most mills in addition to the total volume of effluent waters.
Due to the water treatment it is possible that the content of certain substances per m3 is higher if the water is taken from a river than in the effluent released into the river. In an LCA this would mean that the production of paper could be credited for the reduction in substances. This is illustrated in figure 4.
However, since only a few mills analyse their incoming water the available data cannot be considered as representative. Therefore only data for the emissions to the recipient are given, without taking into account the substances in the incoming water.
Most of the corrugated board plants have internal waste water treatment that can be treated externally afterwards.
In case the waste water is not further treated externally and released to the environment, the emission level of substances is so low that reporting them is not required by authorities. The reported data are therefore based on a small sample.
Besides the substances reported in chapter 4 and the Annex, very few plants have also given data on some of the following emissions: metals (Cadmium, Chromium, Lead, Nickel, Iron, Boron, Aluminium), AOX, Chlorine and Phosphorus. The amounts are below 0,001 kg/tonne nsp.
Allocation of emissions to paper grades when a mill produces more than one paper grade
As far as waterborne emissions per m3 are measured for a mill, these data are well documented.
The figures reported are usually based on continuous measurements according to control programmes set by official authorities. Given emissions to water are measured according to standard methodology.
Where necessary, allocation between paper grades is done according to mass of produced paper grade. There is no technical reason for differences in water consumption, effluent and emissions to water between Testliner and Wellenstoff. However the weighted averages for each paper grade do show differences because different mills are included in the samples. To prevent misunderstanding, the same amounts for water use, effluent and emissions to water for both paper grades are reported as their weighted average.
The water used for the production of White Top Testliner is relatively higher than for Testliner and Wellenstoff. No separate data are reported as the effluent from its production is mixed with that from the production of other grades produced on site.