A small scale down-flow hanging sponge (DHS) reactor was fed with municipal sewage containing linear alkylbenzene sulfonate (LAS) in the range of 0-40mg/L to investigate the effect of LAS on the performance of the DHS reactor and microbial structure of the retained sludge. Even in the duration in which the DHS reactor was fed with sewage with 40 mg/L of LAS, the reactor exhibited around 80% of removal in terms of COD and LAS respectively. Sludge from the DHS reactor with LAS, sludge from another DHS reactor fed with sewage only, and seed activated sludge were shown to form characteristical microbial structures according to principal coordinate analysis. In addition, vertical variation of microbial structure was found in the retained sludge of the DHS reactor fed with sewage containing LAS.

　Concrete pipeline facilities are prone to corrosion and other structural deterioration because the sewerage environment is subject to severe chemical erosion. In a survey of aging manholes in the ward area, deterioration was observed to a certain extent in manholes that had exceeded their legal service life, such as loss of concrete reinforcements due to corrosion caused by sulfuric acid. Most manholes that have exceeded their legal service life are old Tokyo-style manholes, and unlike conventional standard manholes, they have a structure that combines different components, and the effects of deterioration due to corrosion have not been sufficiently verified. By conducting load test using specimens that reproduced the deterioration of old Tokyo-style manholes and a numerical analysis using the nonlinear finite element method, and comparing the results with current standard values such as JSWAS, we evaluated the load bearing capacity and confirmed the structural hazard. In order to reconstruct the manholes, we have decided to introduce a manhole rehabilitation method, which has not been the standard in the past, because their replacement would be a heavy burden. For the introduction of the new method, we decided to certify the manhole rehabilitation method employed as a standard in the reconstruction work based on the newly established technical evaluation standards that specify the required load bearing capacity.