To examine the influence on the COD concentration, respectively freight of different cartonboard grades, the process water was analysed in the waste water treatment plant. Despite certain trends, the results of the thesis are not able to display clear classification of COD concentration with regard to the produced cartonboard grades. In order to disintegrate different types of waste paper on large-scale basis, lab tests were carried out first. The results showed the impact of residence time and time of disintegration on the COD dissolubility. The aim of the thesis was to determine the COD input of all grades of recycled paper and virgin fibre used in the plant. The tests were executed in a low consistency (LC) pulper of the stock preparation. The results show that some recycled paper grades have a high amount of COD dissolubility, whereas other grades even lower the COD of the utilized process water. To be able to draw possible conclusions on the fibre mixtures of the cardboard grades, the COD concentration of the machine chest while production was examined. The following balance showed no explicit coherence between COD concentration and recycled paper recipe.