Summary:

The work contains the evaluation of work of the small rural sewage treatment plant servicing citizens of the Michniów village (Suchedniów community, Świętokrzyskie Province). The basic element of process line is the activated sludge reactor of sequential work, so called SBR. The bases for evaluation elaboration were data allowed by a user of the object. There were: results of treated sewage volume and results of BOD₅, COD₅ and total suspension in not treated and treated wastes determinations, coming from years: 2004-2005. In the regarded two-years period hydraulic charge amounted meanly: in the first year about 75%, in the next year about 89% of designed output, that is 35 m³·d^-1. In the same period in raw sewage average content of BOD5 (577,8 mgO₂⋅dm^-3) and total suspension (488,8 mg⋅dm^-3) were 1,5 times higher, and COD_Cr content (1124,9 mgO₂⋅dm^-3) even 2 times higher than the ones taken in the object design stage. This conjuncture, in situation when sewage treatment plant rejected sewage which were bringing by waste removal tankers could be a proof of illegal pumping contents of house cesspools into sewers sanitary, in case of this properties, which are not connect with yet. In these exploitation conditions the waste purification effects in the waste treatment plant in Michniów should be highly assessed. All the examined treated wastes samples met water supply and sewage effluent disposal content standards taking into account the composition, or didn’t cross a admissible content in case of BOD₅ - 40 mgO₂⋅dm^-3, COD_Cr - 150 mgO₂⋅dm^-3 and total suspension – 50 mg⋅dm^-3. The calculated values of reliability indicators show its efficient and reliable work. Average values of commonly use efficiency of the sewage treatment were for BOD₅ – 91,7%, COD_Cr – 93,6% and total suspension 98,4%. For every of above – mentioned parameters, the calculated values of technological unreliability were zero, and technological efficiency 0,96. The estimation shown in this paper confirm the utility of SBR reactors to cleaning sewage at rural condition, and also give a positive opinion for technological – technical solution adopted by BIOVAC company from Kielce.