Ciliated protozoa in the impact zone of the Uzhgorod treatment plant

¹ State institution of higher education “UzhNU”, Narodna Square 3, 88000 Uzhhorod, Ukraine
² Sumy Makarenko State Pedagogical University, Romenska 87, 40002 Sumy, Ukraine
³ Lublin University of Technology, Environmental Engineering Faculty, Nadbystrzycka 40B, 20-618 Lublin, Poland
⁴ Gdansk University of Technology, Civil and Environmental Engineering Faculty, Narutowicza 11/12, 80-233 Gdańsk, Poland
⁵ Sumy State University, N. Rimsky-Korsakov 2, 40007 Sumy, Ukraine
⁶ Schmalhausen Institute of Zoology National Academy of Sciences of Ukraine, B. Khmelnitsky 15, 01601 Kiev, Ukraine

Abstract

This paper presents the results of studies on the Uzh River (Ukraine, Zakarpattia Oblast) near the effluent point of a sewage treatment plant in Uzhgorod. The samples were taken at various sites of the treatment plant along the stages of purification process, as well as in the river, at a number of different points above and below the wastewater discharge. At each of these objects, the temperature and O₂ were measured. The structure of ciliate assemblage was analyzed along the stages of the treatment process in the WWTP and in the river before and after the sewage discharge. A total of 26 ciliate taxa were observed and included in the analysis. All the studied stations were considered as a continuum in which populations of protozoa spread freely according to their ecological preferences. The majority of ciliate species were encountered in each of the examined stations, but their quantitative development differed significantly, reflecting their response to the environmental conditions at the stations. The analysis of the qualitative and quantitative distribution of ciliate populations by the stations enabled to group them in respect to the peculiarities of the local conditions. The study showed that the majority of the ciliate species, typical of bioreactors, are equally common at the stations of the Uzh River below wastewater discharges. The ciliate assemblage in the oxygen gradient demonstrated a wide spectrum of ecological tolerance at the species level. These findings confirm that ciliates are very good indicators of the environmental quality, provided that detailed information about their environmental priorities is available.