IMPACT OF MARIJAMPOLĖ WASTEWATER TREATMENT PLANT ON WATER QUALITY OF THE ŠEŠUPĖ RIVER

The aim of the paper was to determine the impact of Marijampolė city wastewater treatment plant (WWTP) on the water quality of the Šešupė River. The wastewater and surface water samples were collected from January 2015 until January 2018. The condition of the surface water the Šešupė River condition is assessed 100 meters before the release point and 500 meters after the release point. The results show that the wastewater treatment is treated efficiently. It has been determined that the values all indicators of wastewater treatment efficiency duration of the study was the same (the function was negative, and the determination coefficients were very low: R2= 0. 03; R2= 0.012; R2= 0.0006 and R2=0.034). The treated wastewater is released from the Marijampolė WWTP into the Šešupe River. The highest concentration according to all examined indicators was in 500 meters after the release of the wastewater. All differences were found to be statistically significant. It shows that, although wastewater is efficiently treated, it has a negative impact on the water quality of the Šešupė River.