The Impact of Treated Sewage on Water Quality in Mordarka Stream

This paper presents the analysis and evaluation of the impact of clean sewage on the water in the Mordarka river, in the period 2012–2015. The analysis was conducted based on the collected and statistical research: the amount and composition of the purified sewage discharged to the receiver. The following pollution indices were tested: total suspended solids, BOD₅, COD, total nitrogen and total phosphorus. On the basis of the obtained results it was concluded that the amount of purified wastewater discharge to the Mordarka river, did not contribute to the degradation of the water quality in that period of time. Moreover, the level of indicators: total suspended solid, BOD₅ and COD did not exceed the limit values from the regulation, which confirmed the effective protection of water quality in the Mordarka river. However, because of the high concentration of biogenic compounds in the purified wastewater effluents, the river is prone to eutrophication process.