Ciliated protozoa in the impact zone of the Uzhgorod treatment plant

Abstract

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 O 2 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.

Effect of Stormwater System on the Receiver

“…Wastewater discharge points cause pollutant accumulation and reduce the resistance of aquatic ecosystems [Gücker et al 2006]. Discharging sewage to a river frequently contributes to the processes that lead to a reduction of the dissolved oxygen content or local anoxia [Spänhoff, et al 2007, Wakelin et al 2008, Pliashechnyk et al 2018. Usually, the trophic status of reservoirs changes locally under the influence of influent wastewater [Smith et al 1999].…”

“…Babko et al 2016;Pliashechnyk et al 2018, Majerek et al 2019, then there are much fewer works related to the impact of stormwater runoffs.Bioindication was conducted against the background of water quality assessment using chemical indicators such as BOD 5 and COD. In the literature, there is a some of works relating to the assessment of water quality in the Bystrzyca river within the city of LublinGrzywna et al 2016;Gorzel et al 2018].…”

Statistical analysis of the water pollution indicators pertaining to treated municipal sewage introduced to the river

“…Therefore, due to constantly deteriorating quality of available water resources, only the treated wastewater which meets the requirements stated in valid legal regulations can be discharged to running waters, i.e. rivers [1][2][3][4].…”

“…heavy metals, persistent organic pollutants, potential carcinogens, as well as bacteria, viruses and parasites into the receiver [5][6]. As a result, numerous publications appeared in recent years, aimed at developing the river condition assessment systems [3,[7][8][9][10][11][12][13][14][15][16].…”

“…Obviously, the best results of river condition control can be achieved by simultaneously applying all three groups of assessment criteria (hydro-morphological, physicochemical and biological), unfortunately, such an approach is relatively rare [8]. Moreover, studies are usually conducted in terms of presenting new method of evaluation [3,8]. Much more rarely they are the works aimed at determining the sensitivity of these methods and the degree of agreement and complementarity in the final assessment of river conditions [17][18][19][20].…”