The wastewater treatment plant in Dygowo has been operating since the year 2000. Sewage treated in the plant comes from all over the commune, as well as leachate transported from the landfill in Rymań. It is a mechanical-biological wastewater treatment plant treating on average 300 m3/day of sewage in 2 SBR reactors. The reactors are circle-shaped and divided into identical tanks (forming separate SBR reactors) with internal (closed) denitrification chambers. Raw sewage is sent to the denitrification chamber and then through outlets placed at the bottom of the chamber (slow flow) to the SBR reactor in which aeration, sedimentation and decantation occurs. Decantation of treated effluents is caused by uplift pressure from sewage flowing out of the decantation chamber due to the chamber filling with raw sewage and the operation of the air (decantation) blower. When the level of liquid in the denitrification chamber is high, sewage flows out of the chamber into the SBR reactor due to hydrostatic thrust through apertures in a pipe placed around the inner circumference of the reactor. Surplus sludge is collected from the chamber at a rate of 15-25 m3/day and transported to the wastewater treatment plant in Grzybowo. The treated effluents are sent via a conduit to Olszynka River. This wastewater treatment plant is trialling the use of natural zeolite to treat the sewage. The SBR reactor was dosed with zeolite in loose form during the sewage aeration phase. The research showed a positive influence of the mineral on biological sewage treatment.