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

采用18S rRNA基因克隆技术对UASB处理生活污水中试厂的厌氧原生动物进行了鉴定，以明确其中存在的种类。根据每个物种的丰度是通过显微直接计数在三年内测量的。在UASB中大量存在的原生动物主要是涡虫、古型后生动物、扁穗毛虫。原生动物的细胞总数随着污水温度的变化而变化，秋季达到11×103个/毫升，春季达到0个/毫升。FISH分析表明，在一个原生动物细胞中，有104个细胞利用产甲烷菌作为共生菌利用氢气。Metopus sp在减少UASB中MLSS的捕食方面发挥了重要作用。

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.