Community Characteristics Of Ciliates In Yanerwan Sewage Plant In Lanzhou

From February 2006 to January 2007, a research about community characteristics of ciliate was studied in Yanerwan sewage plant in LanZhou city. During the investigation, three selected sampling sites included aerator and two contrast sampling sites, which were entrances site and exit site. Sampling once every month and then return to laboratory to analyze. In one year, seventy three species of Ciliates, belonging to three Classes ,eleven orders,twenty nine families, and thirty four genera were identified. And twenty six species of Ciliates were recorded in entrances site, fifty four ones in aerator and fifty one ones in exit site . Colpodida and Peritrichida were dominant groups in entrances site, Peritrichida and Pleurostomatida in aerator, Peritrichida, Pleurostomatida and Hypotrichita in exit site. The result showed that Vorticella microstoma , Vorticella convallaria , Vorticella octava , Trachelophyllum pusillum, Opercularia phryganeae, Aspidisca costata, Litonotus fasciola were dominant species in the activated sludge. Heterotrichida were incidental groups, Cyrtophorida and Hypotrichita were common groups.The result of comparative analysis showed that the species number, the species abundance and the species diversity index in the activated sludge were larger than those in two contrast sampling sites. The similarity of ciliates in activated sludge was very different from entrances site,but very similar to exit site. In addition, the seasonal dynamics of ciliates in three sampling sites was very different from natural ecosystem. The seasonal summit of entrances site and exit site was not very conspicuous. The result also showed that the water quality of entrances on July 2006 was the best, that of aerator on May 2006 was the best and that of exit on April 2006 was the best .But the water quality of exit did not accord with the standard of letting out. The ciliates community in the activated sludge was very richness, because aerator is an artificial ecosystem and plenty of oxygen was added constantly.The result of study also showed that dominant species of Peritrichida in aerator could be severed as bioindicator of sewage treatment , because there was close relation between them. The community structure of ciliates in Yanerwan sewage plant was very different from that in other kinds of sewage plant.