Elucidation of the clarification mechanism of the zero emission oriented toilet system by analysis of bacterial flora

在零排放的厕所系统中，人类排泄物在曝气池中被氧化并被引入木屑池。人们认为那里正在进行生物治疗，但其机制尚不清楚。为了解决这一问题，本研究旨在通过分子系统发育分析来确定实际运行的厕所系统和实验室规模的模型化粪池系统的细菌植物群。实际运行的厕所系统的细菌植物群由大量的噬细胞黄杆菌类杆菌（CFB）群细菌组成，建立了实验室规模的模拟化粪池系统，并对其水质和细菌植物群进行了分析。对磷、氮、BOD和COD的去除效果进行了初步验证。约两个月后，盐浓度增加，BOD去除率下降。实验室规模的模型化粪池中细菌植物群的分析结果与实际运行的厕所系统的情况相似。植物群以CFB群细菌为主，并鉴定出以下细菌属：Ctytophaga、Clostridium、Chitinophaga、Leuconostoc、Microbulbifer、Oxalophagus、Planctomorphia、Ruminophila、Thermoanaerophilia、Vibrio和Sphingobacteriales，表明木片罐中的主要细菌为CFB群细菌。认为CFB群细菌和其它细菌在零排放厕所系统中消化人类粪便。有人认为，澄清功能的下降与盐浓度的上升有关。因此，重要的是考虑不降低BOD去除率的措施。

In the zero emission oriented toilet system, the human excrement is oxidized in the aeration tank and is led into the wood chip tank. It is thought that biological treatments are being done there, however its mechanism is not clarified. To settle this issue, this research project aimed to determine the bacterial flora of the actually operating toilet system and of the laboratory-scale model septic tank system by molecular phylogenetic analysis.The bacterial flora of the actually operating toilet system was comprised of a large share of Cytophaga-Flavobacterium-Bacteroides(CFB) group bacteria, Eubacterium tenue relative, genus Ochrobactrum relative and Gram-positive low GC group bacterium.The laboratory-scale model septic tank system was constructed and analyzed the water quality and the bacterial flora successively. The removal of phosphorus, nitrogen, BOD and COD was confirmed for a while. About two months later, the salt concentration had increased and the removal of BOD had decreased. The result of analysis of bacterial flora in the laboratory-scale model septic tank was similar to the case of the actually operating toilet system. The flora were represented by CFB group bacteria, and following bacterial genera were recognized; Ctytophaga, Clostridium, Chitinophaga, Leuconostoc, Microbulbifer, Oxalophagus, Planctomyces, Ruminobacter, Thermoanaerobacter, Vibrio and order Sphingobacteriales.Taken together, these results suggest that major bacteria in the wood chip tank are CFB group bacteria. It is thought that CFB group bacteria and the other bacteria digest the human excrement in the zero emission oriented toilet system. It has been suggested that the decline of the clarification function associated with the rise of the salt concentration. It is, therefore, important to consider the measures not to decrease the removal of BOD.