Summary:

The paper presents the results of the research regarding the amount of sewage inflowing by the sewerage system and the amount of sewage brought to the collective sewage treatment plant in Nowe Brzesko with the sanitation vehicle. The analyzed treatment plant is located in the area of Nowe Brzesko town in Nowe Brzesko Economic Area on the left bank of the Vistula River. Domestic sewage from 250 buildings are drained into this object. The analysis of the amount of sew-age was carried out in the period from January 2005 to December 2007. In this period the amount of sewage inflowing and brought in each month was defined in order to compare this amount with the designed one. Moreover, the paper presents the frequency of the defined amounts of inflowing sewage occurrence, as well as the probability of their occurrence. After data analysis, it was stated that the tested object is hydraulically under-loaded. In 2005 the actual amount of treated sewage constituted only 20,4% of the established treatment plant capacity, in 2006 this amount was 22% and in 2007 – 26,7%. In the period of 3 years high irregu-larity of the amount of incoming and brought sewage in each month was noticed. Fluctuations of the amount of inflowing sewage valued respectively: for 2005 from 28,8 m3∙d^-1 to 64,6 m3∙d^-1, for 2006 from 40,1 m³∙d^-1 to 66,5 m³∙d^-1 and for 2007 from 49,8 m³∙d^-1 to 84,9 m³∙d^-1. On the other hand the extreme values of the brought sewage were: from 2,6 m³∙d^-1 to 6,4 m³∙d^-1 in 2005, from 3,0 m³∙d^-1 to 7,8 m³∙d^-1 in 2006 and from 4,3 m³∙d^-1 to 10,3 m³∙d^-1 in 2007. The brought sewage was found to account from 8,2% to 11,5% of the total actual hydraulic loading of the sewage treatment plant. Additionally, it was stated that the most often occur-ring inflow was from 30 m3∙d^-1 to 60 m3∙d^-1 sewage inflow or from 60 m³∙d^-1 to 90 m³∙d^-1. These ranges covered for almost 85% of all incoming sewage which happened in the analyzed period. The other average-daily amounts of inflowing sewage happened incidentally.