High efficiency and stability in the UASB fed with domestic sewage by high abundance of anaerobic protozoa 1

利用18 S rRNA基因克隆技术对UASB处理生活污水中试装置中的厌氧原生动物进行了鉴定。通过显微镜直接计数测量了三年内每个物种的丰度。当原生动物数量较多时，扭纹细足虫、古细足虫、扁扁三肢虫是优势种。原生动物的总细胞数随着污水温度的变化而变化，秋季为11 × 103个/mL，春季为0个/mL。对捻转绿足虫的FISH分析表明，在一个原生动物细胞中存在104个产氢甲烷菌作为它们的共生菌。Metopus sp通过捕食作用对UASB中MLSS的降低起重要作用。

Identification of anaerobic protozoa in an UASB pilot plant treating domestic municipal sewage was carried out by 18S rRNA gene cloning to clear how many species existed in. Abundances according to each species were measured by microscopic direct counts throughout three years. Metopus contortus, Metopus palaeformis, Trimyema compressum were predominance as a protozoan in the UASB when present in large numbers. Total cell number of the protozoa shifted with changes in temperature of the sewage, and up to 11x103 cells/mL (fall) and became 0 cells/mL (spring). FISH analysis to Metopus contortus revealed that hydrogen utilizing methanogen present at a level of 104 cells in one protozoan cell as their symbiotic bacteria. Metopus sp played a important role to reduce MLSS in the UASB by their predation.