Analysis of the Proportion of Incidental Water in Annual Wastewater Inflows to a Selected Treatment Plant During a 15-Year Observation Period
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Department of Sanitary Engineering and Water Management, Faculty of Environmental Engineering and Land Surveying, University of Agriculture of Krakow, Mickiewicza Ave 24/28, 30-059, Krakow, Poland
Grzegorz Bogusław Kaczor   

University of Agriculture of Krakow, Mickiewicza Ave 24/28, 30-059, Krakow, Poland
Publication date: 2021-07-06
J. Ecol. Eng. 2021; 22(7):204–211
The main aim of the study was to determine whether the amount and share of incidental water in wastewater inflows to the sewage treatment plant increased with the age and development of the sewage system. The object of the study is a small sewerage system located in southern Poland, in the Lesser Poland Province, 15 km north-east of the Kraków city. Analysis of a 15-year observation series of daily wastewater flows, from 01.01.1994 to 31.12.2018, allowed a reliable assessment of the actions taken by the sewage system operator to reduce sources of incidental water inflow to the sewage network. The study showed that the percentage share of incidental waters in the annual wastewater inflow to the analysed treatment plant decreased from 35.9% in 2004 to 8.4% in 2018. This reduction should be treated as a success of the remedial actions of the sewage system operator. However, the study showed at the same time that in 2017 alone, 56 709 m3 of incidental water flowed into the analysed sewerage system, compared to 166 075 m3 of wastewater. A similar case was repeated in 2013, when 53 060 m3 of incidental water and 132 860 m3 of real wastewater flowed into the treatment plant. These cases show that all remedial measures by the network operator are still insufficient when heavy and long-duration precipitation occurs in a given year.