THE EVALUATION OF THE PERITRICHIA (CILIOPHORA, PERITRICHIA) NUTRITION RATE IN THE SEWAGE TREATMENT PLANT
The peritrichous infusoria - is one of the main organism groups in activated sludge in the sewage treatment plant. As the result of their filtering activity sewage cleaning takes place, activated sludge flakes structural characteristics ameliorate. The peritrichia indicative meaning is important too. They react to sewage treatment plant technological regime changes both morphologically and physiologically. That`s why we suggest using their nutrition rate - the square number of food vacuoles - for evaluation of cleaning sewage quality.Nutrition in peritrichia goes with certain rhythm. Maximum nutrition intensivity is registered in favourable environmental conditions. In unfavourable conditions infusoria stop their nutrition and sewage water cleaning deteriorates. Earlier we evaluated some peritrichia species nutrition rate in activated sludge from aerotanks with sewage water from dwelling quarters. But we didn`t investigate this index in activated sludge of industrial sewage.The aim of this work is to investigate the dependence of peritrichia nutrition rate on hydrochemical indices of activated sludge from industrial sewage.The activated sludge was investigated every season during 2007-2013. 250 samples were taken. The samples were taken from aerotanks in two sewage treatment plants in Zhytomyr. On the first plant sewage water mainly from dwelling quarters was collected, while in the second - from industrial enterprises, such as meat- processing factory, plants where plastic windows and bags are produced, etc. The peritrichia were investigated in living state. The activated sludge was constantly aerated in the laboratory. To investigate the nutrition rate activated sludge was poured into Petri cups (d=3,5 cm) 2,5 ml each, then 0,01 ml of liquid black ink “Gamma” (Moscow, Russia) was added and after 10 minute exposition the number of food vacuoles with ink was calculated. As the index of peritrichia nutrition rate we used square number of food vacuoles. Obtained data were processed with STATISTICA 6,0 program.All in all 26 peritrichia species were registered in activated sludge of these plants. Average indices of peritrichia nutrition rate in these two Zhytomyr plants were analyzed during the whole period. Nutrition rates and their dependence on activated sludge hydrochemical indices were investigated in the following species: Vorticella convallaria (Linnaeus, 1758), V. alba Fromentel, 1874, V. submicrostoma Ghosh, 1922, V. microstoma Ehrenberg, 1830, Carchesium batorliqetiense Stiller, 1953, Epistylis рlicatіlis Ehrenberg, 1831, E. longicaudatum Banina, 1983, E. еntzii Stiller, 1935, E. epibioticum Banina, 1983, E. coronata Nusch, 1970, Thuricola similis Bock, 1963 та Pyxicola аffinis Kent, 1881.The highest average indices of nutrition rate are in peritrichia colonial forms: E. plicatilis (108,59), E. entzii (82,59), E. longicaudatum (72,07) та E. coronata (57,02). In our opinion it`s the result of mutual activity of zooids from one colony. Approximately equal nutrition rate is in V. alba (24,83), V. convallaria (19,38), C. batorligetiense (27,74), P. affinis (21,65) and T. similis (22,30). The lowest indices of nutrition rate are in such species as V. microstoma (11,24) та V. submicrostoma (12,92). Amongst the colonial forms the lowest average nutrition rate index is in E. epibioticum (26,56) due to zooids smaller size. According to the investigation results peritrichia nutrition rate greatly slows down during sewage cleaning technological regime breach. One of the reasons is hydrobionts intoxication with toxic substances from primary settling tank in which fresh sediments were not removed thoroughly. In such conditions peritrichia activity lowers, their peristoms draw into and the cilia movements become sluggish. It results in lower number of food vacuoles the square of which is the nutrition rate index. Also, if the cleaning regime changes, hydrochemical indices such as dissolved oxygen, active environmental reaction which directly influence peritrichia nutrition rate change too.The dependence of peritrichia nutrition rate on activated sludge hydrochemical indices is researched. In all researched species the direct dependence of square number of food vacuoles and the dissolved oxygen in activated sludge is established. But for majority of them the correlation coefficients were less then 0,2. The low correlation can be explained by the constant dissolved oxygen level maintained by workers for normal sewage cleaning. Only in C. batorliqetiense, V. microstoma та V. submicrostoma correlation coefficients are 0,75, 0,60 and 0,35, that`s why the square number of their food vacuoles can be recommend as the indicator of oxygen level in aerotank sewage.Inverse dependence in nutrition rate and sludge indices is clearly seen in such species as P. аffinis, T. similis and E. longicaudatum. Their correlation coefficients are -0,71, -0,73 та -0,68 accordingly. These three species are more sensitive to pressure change and quickly react to sludge reloading with low nutrition rate. That`s why square number of their food vacuoles can be recommended as indicator of AS pressure.S.I. Metalnikov admitted increase of nutrition rate in paramecium in low-acid environment and its decrease in low-alkaline one. The same tendency is observed in peritrichia in activated sludge. In our research the pH level was constant. The highest inverse dependence in nutrition rate and pH level is in V. microstoma, V. submicrostoma, E. coronata та C. batorliqetiense. Their correlation coefficients are -0,42, -0,46, -0,52 and -0,38 accordingly/The results of our research show great difference in peritrichia nutrition rate in two sewage treatment plants. All peritrichia species have lower square number of food vacuoles in industrial sewage if compared with that from dwelling quarters. Most probably it is connected with industrial sewage toxicity.The further investigation of peritrichia nutrition rate, enlisting indicative species for registering fluctuations of activated sludge hydrochemical indices, establishment of peritrichia indicative species in industrial sewage are promising. It is important to implement the investigation results into the practice of sewage cleaning monitoring for quick reactions to technological regime violations.