Water utilities in Japan should redeign their water distribution system considering the decrease of water demande and rebuilt their deteriorated distirbution pipes. The purpose of this study is to examine the concept of water distribution system redesigning from the viewpoints of self-cleaning function, fire protection function, and earthquake disaster resilience. In this study, a procedure of downsizeing and redesigning of water distribution network applied to the actual water distirbution system in Kobe City, the performance of fuctions in seld-cleaning, fire protetion, and earthquake disaster resilience were evaluated. As a result, a tradeoff between self-cleaning function and fire protection fuction was pointed out. In addition, it was indicated that the balance between earthquake disaster resilience and self-cleaning fucntion is requied for water system in Japan.

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 It is important to secure the rest area for fish. Fish has the ordinary and dark muscle. When fish uses ordinary muscle, fish gets tired. In such a situation, fish needs a rest. In this study, vegetation density in open-channel is changed. The trajectories of Zacco platypus's were observed. It was found that Zacco platypus utilized a slow of the speed as rest space. Stay in vegetation area increases with an increase of vegetation density. An approach rate to vegetation area rises with an increase of vegetation density. However, It was not found that clear relationship with a migration rate of Zacco platypus and vegetation density.

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 Our previous research suggested that the entrance selection of a multiple path fishway affects migration success ratio. In this research, firstly, we prove that entrance selection affect migration success through field experiment. Secondly, we determine suitability index for air bubble condition, which were 0.27 for no bubble, 0.88 for surface bubble, 1.00 for bubble reaching mid-depth, 0.16 for bubble reaching the bottom. They are opposite results to the existing research. It seems that air bubble itself is not preferred but the cover created by air bubble is preferred. Thirdly, we conduct entrance selection experiments in the field, and found that the major mechanism of entrance selection was air-bubble, followed by velocity. Sound pressure and depth affected little.

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 We investigated gene flow of 15 aquatic insects (3 of Ephemeroptera species; 12 of Diptera, Chironomidae species) in Shigenobu River (Ehime, Japan) using Next-Generation DNA Sequencing (NGS) system. We collected aquatic insects from 10 sites. Mixed DNAs from each site were extracted from mushed community sample. Cytochrome Oxidase subunit I region in mitochondrial DNA were amplified by COI primer with DNA tag indicating each sampling site and were genotyped using GS FLX system. Comparison of pairwise Fsts between flagmented sited and between non-flagmented sited by intermittend interval showed that most spesies were not interrupted by intermittent interval other than Baetis sp. MK-2015d and Chironomus kiiensis. Although Chironomidae was predicted separated genetic structure and low gene flow because of their wing and body size, average pairwise Fst supported stronger dispersal than Ephemeroptera. Chironomidae might dispersal by wind passively and could use habitat outside of river such as rice field. The limitations of this study were power of DNA reading by NGS and DNA barcording to identify species name. Because several dominant species were not detected, ideal sample volume must be clarified. In addition, The current DNA database have less information about Japanese aquatic insects. Study species could be expanding by DNA information in the database increased.

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 The purpose of this study is to propose a prevention measure against algal abnormal proliferation in a scenic effluent channel of a wastewater treatment plant in Kobe, Japan. We conducted field work on water quality and algal identification for clarifying the cause of the algal abnormal proliferation and laboratory experiments for demonstrating the inhibiting efficacy of algal growth by NaOCl and seawater. As the results of the field work, it found that main alga in the channel is Fragilaria neoproducta and that the algal abnormal proliferation is caused by features of water quality and structures in the channel. And as a result of the laboratory experiments, it found that NaOCl has the strong inhibition effect of algal growth but also affects growth of Porphyra seaweed in discharged area from the channel. In addition, the result of the experiments demonstrated that seawater does not have the strong inhibition effect of algal growth but has the distributing efficacy of the alga forming colony.

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 Rice for animal feed (cultivar Bekoaoba) was cultivated using a bench-scale apparatus of paddy field with continuous irrigation of treated municipal wastewater, instead of nitrogen and potassium fertilizers. The growth of rice plant was comparable to that cultivated with circulated irrigation in our previous study, although more than twice amount of treated wastewater was used. On the other hand, the protein content (up to 13.1%) in the harvested rice was much higher than that in the previous study and the standard expected in normal paddy fields. Such rice with high protein content can be cultivated in a normal paddy field if a large amount of fertilizers is applied. This study revealed that the continuous irrigation of tread wastewater can produce a high quality of rice for animal feed with a satisfactory yield, saving the cost of fertilizer.

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 In this study, we investigated if sewage sludge (dehydrated sludge) could be a nutrient supplement for growing oyster mushrooms, aiming for the expanded use of biomass generated from sewage treatment plants. As the result, though the sewage sludge was not effective alone, it accelerated mycelial growth, shortened the cultivating term by 10 days (the maximum) and increased the yield by 20% per 10g of the medium when it was combined with dry solid sweet potato shochu-lees. As for the nutritional effect, the fruit bodies from the sewage sludge and dry solid sweet potato shochu-lees media contained 3.4 times of free amino acid compared with those from the conventional media. No heavy metals such as Cr, were not detected in the fruit bodies from the sewage sludge and dry solid sweet potato shochu-lees media.

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 For elucidating cleaning mechanism of membrane surface by bubble flow in follow fiber membrane module used in MBR reactors, influence of hollow fiber density on water-phase velocity properties inside membrane modules was investigated using a PTV method. It was concluded that when the hollow fiber density is larger, frequent collisions between bubbles and hollow fibers results in collision of bubbles and smaller water phase velocity and turbulent intensity. However, it was also made clear that larger hollow fiber density resulted in larger eddy viscosity inside membrane modules suggesting necessity of further researches related to influence of hollow fiber density on strength of membrane cleaning.

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 Membrane fouling caused by natural organic matter (NOM) hinders widespread application of microfiltration (MF) and ultrafiltration (UF) to water treatment. In this study, we focused on biopolymers, which are hydrophilic organic matter with large molecular weights and have been reported as primary foulants in recent studies. Influence of size of biopolymers and pore sizes of MF/UF membranes on evolution of membrane fouling was investigated. It was found that coagulation by polyaluminum chloride and anion exchange removed different fractions of biopolymers: coagulation removed biopolymers with large molecular weights (>1,000,000 Da) whereas anion exchange removed biopolymers with small molecular weights (<100,000 Da). Fouling in MF was significantly mitigated when the feed water was treated by coagulation, indicating that biopolymers with large molecular weight were the primary foulants in MF. Pretreatment by anion exchange followed by coagulation substantially removed biopolymers, leading to efficient control of membrane fouling in MF. The high removal of biopolymers by anion exchange followed by coagulation could be attributed to the fact that humic substances were significantly removed by anion exchange: more amounts of coagulant became available to react with biopolymers as a result of elimination of humics. When UF membrane was examined, evolution of irreversible fouling hardly occurred. This could be explained by the size of biopolymers. They could not intrude into pores of the UF membrane. However, small particles rejected by the UF membrane could cause reversible fouling.

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 A super-resolution microscopy, i.e. Stochastic Optical Reconstruction Microscopy (STORM), was applied as a new visualization method of internal membrane fouling. The purpose of this study was to evaluate the backwashing and chemical cleaning effectiveness on ultrafiltration membranes fouled with BSA by using Confocal Laser Scanning Microscopy(CLSM) and STORM. Comparing BSA-Alexa Fluor 647 conjugate with BSA which was labelled by Alexa Fluor 647 after chemical cleaning, the latter was not influenced by chemical cleaning and had a good emission in the analysis of CLSM and STORM. However, it would lead to false luminescent spots in STORM analysis if the rinse was not well done. In the analysis of CLSM, BSA fouled within the separation layer of membrane was quantified successfully, but a small quantity of BSA inside the membrane was not detected. On the other hand, in the analysis of STORM, though it could not fully quantify BSA, a tiny quantity of BSA fouled inside was visualized at a higher resolution than ever. Hence, it was concluded that the combination of CLSM and STORM was efficient for the analysis of foulants on the surface of and inside the membrane.

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 We studied temporal effects of slit installation on a check dam on stream habitat and macroinvertebrates in the Wasada River located at Yamagata Prefecture in Japan. Quantitative sampling of benthic macroinvertebrates and measurement of channel morphology were carried out at the inlet and outlet sites of the two check dams in the studied river more than once per year through 2009 to 2015. The dam at downstream was slit in August 2010. The channel morphology was measured using a high precision Global Position System (GPS) and classified into 7 habitat types (e.g., riffle and pool), which was subsequently used for calculating habitat diversity. As results, while the habitat diversity increased at the inlet site of the slit dam after the slit event, species diversity of benthic macroinvertebrates did not display any trends over time. This may suggest that, at least within a few years, local habitat diversification would only result in a fraction of contribution to species diversity. We observed significant negative correlation between the species diversity and the ratio of lentic habitat (R²=0.35, P<0.05) in contrast to an earlier study, indicating that increase in lentic habitat at a given stream (or reach) might diminish species diversity of stream macroinvertebrates.

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 We investigated the potential effect of sediment bypass tunnel that mitigate the ecological impact of dam reservoir on fragmented stream macroinvertebrate communities in Southeastern Swiss Alps. Using metabarcoding approach, we compared Bray-Curtis community's dissimilarities within rivers among 3 types of rivers: rivers fragmented by dams, rivers connected by sediment dam-bypass tunnel, and reference rivers (i.e. no dams).Among the three bypassed dams investigated, two showed significantly lower dissimilarities across the bypassed dams than non-bypassed dams, supporting the ecological mitigation effect of sediment bypass tunnel. However, one bypassed dam did not show a mitigation effect. This bypass has been operating only for 2 years, a period much shorter than the other two (=39 and 93 years), hence the elapsed time of bypass operation may not be enough to produce a mitigation effect. Overall, our metabarcoding approach allowed the rapid assessment of community structure of huge samples (i.e. 7369 individuals) collected from abroad for our research. Several technical limitations in the use of metabarcoding such as unsuccessful detection of rare taxa were also presented in this study.

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 Essential fatty acid (EFA), which are vital nutrient for all aquatic animals, have been considered to be produced by algal species in aquatic ecosystems. In this study, ability of EFA biosynthesis of protozoa, Cyclidium sp. and Glaucoma sp. was examined under 1 month culture experiment with Alcaligenes faecalis as EFA deficient diet. Results showed that these protozoa could continuously grow without supply of EFA. Moreover, it is also revealed that Glaucoma sp. and Cyclidium could synthesize 18:2n6, and 18:3n3, 20:5n3, 22:n6n3 de novo, respectively. These findings predicts the role of protozoa as EFA producer for other aquatic animals in the ecosystems where algal production are limited.

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