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

在零排放导向的厕所系统中，人类排泄物在曝气池中被氧化，并被引入木屑池。据认为，生物治疗正在进行，但其机制尚不清楚。为了解决这一问题，本研究项目旨在通过分子系统发育分析确定实际运行的厕所系统和实验室规模模型化粪池系统的细菌菌群。实际运行的厕所系统菌群主要由细胞噬菌-黄杆菌-拟杆菌（CFB）群菌、真杆菌（Eubacterium tenue）群菌、Ochrobactrum群菌和革兰氏阳性低GC群菌组成。建立了化粪池系统的实验室规模模型，并对其水质和菌群进行了分析。对磷、氮、生化需氧量和COD的去除已有初步证实。约2个月后，盐浓度升高，BOD去除率下降。实验室规模模型化粪池细菌菌群分析结果与实际运行的厕所系统情况相似。菌群以CFB群菌为代表，鉴定出以下菌属；噬细胞菌、梭菌、几丁菌、白质菌、微球菌、食草菌、植物菌、反刍菌、热厌氧菌、弧菌和鞘菌目。综上所述，这些结果表明木屑槽中的主要细菌是CFB群细菌。人们认为，在以零排放为导向的厕所系统中，CFB群细菌和其他细菌消化人类粪便。有人认为，澄清功能的减弱与盐浓度的升高有关。因此，考虑不降低BOD去除率的措施是很重要的。

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.