The paper presents analysis of influence of amount of pollutants, described as BOD₅, COD and total suspended solids, in the sewage from the cutting plant, butchery of pigs and from the tenants on their concentration in the sewage which flow into the treatment plant Bioblok PS-50 in Gruszow. Average concentrations of pollutants in the sewage mixture were calculated on the basis of the weighted mean. The disturbances of the treatment plant operation were found to be caused by too high concentrations of the above mentioned pollution indexes. On the basis of the calculated weighted mean the average amount of BOD₅ index was 592,1 mgO₂ ∙ dm^–3, COD – 974,8 mgO₂ ∙ dm^–3, whereas the total suspended solids 570,7 mg ∙ dm^–3. In order to decrease the concentration of pollutants in the raw sewage which flow into the treatment plant, should be enlarge the proportional participation of domestic sewage with 82% to 96%. Moreover the existing industrial sewage pretreatment system needs to be modernized or a new one needs to be installed in the exact place of the sewage origin.

3-10