Main objective of this study was to understand the adsorption characteristics of perfluorinated compounds (PFCs) and polycyclic aromatic hydrocarbons (PAHs) on microplastics in Lake Biwa and Osaka Bay. Microplastics (315 μm-5 mm) in surface water were collected and 15 types of PFCs, 16 types of PAHs and 4 types of harogenated PAHs were analyzed simultaneously. Target chemicals on microplastics were found at 49-218 ng/g-dry (Σ15 PFCs), 1,730-27,100 ng/g-dry (Σ16 PAHs) and 29-799 ng/g-dry (Σ4 harogenated PAHs), respectively. It was suggested that each compound was adsorbed on microplastics by hydrophobic effect, because target chemicals' contents ratio (chemical content on microplastics/that in dissolved phase of surface water) increased as their octanol/water partition coefficient (log Kow) increased. In addition, it was assumed that micoroplastics with smaller diameter tended to con-tain more PAHs.

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 Main objective of this study was to understand the occurences of total organic fluorine (TOF), the component perfluorinated compounds (PFCs) and their formation potentials (PFC-FPs) in the Lake Biwa – Yodo river basin. Total of 68 water samples (9 lake water samples, 45 river water samples and 9 wastewater treatment plant (WWTP) effluents) were collected during August to October 2016. TOF was analyzed by Combustion Ion Chromatography and PFCs and PFC-FPs were analyzed by LC-MS/MS. As a result, 1) TOF concentrations in 67 samples were detected at more than limit of detection (32 ng-F/L). 2) The ratios of Σ15 PFCs in TOF concentration were not significantly different among each water sample type (lake water, river water and WWTP effluent) and average value was 22%. 3) TOF concentrations were detected higher in the order of WWTP effluent, river water and lake water on average (748, 458, 175 ng-F/L, respectively) in the Lake Biwa – Yodo River basin while it was detected at 115,138 ng-F/L in effluent from a single WWTP (N-WWTP) in the Ai river basin, suggesting that there was a specific point source. 4) TOF and PFC-FPs loading from N-WWTP were calculated as 30,740 g/day and 8,807 g/day respectively, which were 2.2 and 3.2 times higher than the loading at the downstream of Yodo river where the flowing water flux was 47 times higher. It was suggested that unknown PFCs relatives were discharged from N-WWTP.

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 Trace metals in natural water such as iron, copper and zinc are essential micronutrients for aquatic organisms. However, they pose toxin when they are present in excess. It is known that the bioavailability and toxicity of metals depend on the concentration of inorganic metals, not the total metal concentration. Therefore it is important for the conservation of aquatic organisms to understand the chemical form of metals (i.e. chemical speciation). In this study, we analyzed and compared trace metal speciation in urban rivers affected by human activities such as wastewater and natural rivers with small influence on the Sagami River basin. As a result, it was suggested that the concentration of dissolved organic matter is relatively small in the natural river, and therefore the inorganic metal concentration increases due to lower degree of complexation, resulting in the higher bioavailability of metals.

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 To investigate the change in water quality from the source to the point-of-consumption (PoC), we collected and analyzed 56 water samples from various points of an intermittent water supply system in the Kathmandu Valley, Nepal. Compared to treated water from treatment plants, distribution network samples showed large spatial and temporal variations in total dissolved solids (TDS), Fe, Mn, NH₄-N, coliforms, and free and total chlorine concentrations due to irregular supplies, intrusion of contaminants, and uneven dosing of disinfection chemicals. Water quality in the household storage tanks was poorer than that in the distribution network for TDS, NH₄-N, E. coli and total coliforms, suggesting contamination in the storage tanks. There were no significant differences in water quality in the rooftop and the basement tanks, yet the median TDS, Mn, and E. coli concentrations in the rooftop tanks were higher than in the basement tanks possibly because of its exposure to the environment and low frequency of cleaning. The age of the basement tank and the source of water (piped or tanker-delivered) had no effect on the microbial quality of the stored water, whereas higher cleaning frequency significantly reduced E. coli concentrations. Household water treatment systems were effective in reducing NH₄-N, Mn, Fe, TDS, and E. coli concentrations, but total coliform concentrations increased at the PoC possibly due to microbial regrowth or improper storing and cleaning practices. Guidelines for maintaining residual chlorine levels in the basement tank and redesigning rooftop tank to ease cleaning are suggested as potential measures to improve water quality during storage.

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 In order to introduce Japanese Johkasou as wastewater treatment system in the EU region it is necessary to collect and organize information for appropriate sludge management. A research was carried out examining the volume of sludge generation and sludge storage capacity for a small-scale wastewater treatment plant installed as a model for the EU region. This study focused on the difference of wastewater flow and pollution loading amount when testing Johkasou system performance in the EU and Japan. The Japanese model of wastewater treatment plant (Johkasou) was redesigned for the EU model whilst the BOD volumetric load was set equal for both models. The results of a field test of the EU model were compared with those of Japanese Model.
 The results showed that the amount of sludge discharge from the EU model was 1.1 L per capita per day was lower compared to the 1.5 L per capita per day of Japanese model. This was attributed to high catabolism rate of the EU model. Therefore, it was concluded the EU model generated less sludge per BOD inflow load. Furthermore, the ratio of volume of sludge generation to retention time in the primary treatment tank was confirmed and it was revealed that the progress of denitrification caused suppression of sludge generation.

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 The effect of aeration rates on the treated water quality of gappei-syori Johkasou was evaluated by changing the setting condition for the blowing air rates of 11 household gappei-syori Johkasou; and the relations among all measured quality indexes were analyzed through correlation and principal component analyses. Of the total 11 Johkasou targeted, 7 Johkasou showed improvement in their performance through changing the blowing air rates alone, reflected by concentration decreases of BOD and elevations of transparency for the water after treatment. The results of correlation and principal component analyses showed that, in addition to SS, VSS and organic nitrogen, particles in the size range of 0.5-1.0μm, ORP and nitrification were closely related to the organic loading represented by BOD and C-BOD. The changes in the concentration of DO brought about by changing the blowing air rates was shown to positively affect the settling property of sludge.

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 Basalt fiber is a material made of extremely fine fibers of basalt. It is used as a fireproof textile in aerospace and automotive industries. Recently, it was discovered that suspended solids in water are attached onto basalt fiber. An experiment was conducted on the adhesion efficiency of suspended solids (SS) present in the Johakasou effluents onto basalt fiber. The investigation was carried out to study the potential of basalt fiber in removing SS from the Johkasou effluents. The results of the batch test showed that SS were reduced to less than 1 mg/l after treatment in a sample whose concentration was 200 mg/l before treatment, and that the adhesion of SS on basalt fiber is a fast process. The results of immersing basalt fiber in the existing Johkasou system indicated that the SS and BOD decreased in the johkasou effluents. Furthermore, the Johkasou effluents achieved a stable improved quality that was less than the effluent quality target (BOD ≦20 mg/l, water transparency ≧30 degrees), and could be maintained for a long period. Therefore, the quality of the water treated with basalt fiber could be improved.

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 Effects of water-saving devices on greenhouse gases emission from an on-site domestic wastewater treatment facility, Johkasou, were investigated. After installing water-saving devices, high CH₄ peak was observed under the normal operation condition, however, introduction of anaerobic-aerobic circulation reduced CH₄ emission. Considering greenhouse gases emission from water use, highest emission of 671.6 kg-CO₂ eq house^-1 year^-1 was estimated in the case of no water-saving devices and normal operation condition. Lowest emission of 418.2 kg-CO₂ eq house^-1 year^-1 was achieved with water-saving devices and anaerobic-aerobic circulation. It is clarified that introduction of water-saving devices and anaerobic-aerobic circulation reduce greenhouse gases emission by approximately 38%.

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 Anaerobic digestion of sewage sludge and utilization of digested sludge as liquid fertilizer is a promising energy and resource recovery technology in small facilities, where oxidation ditch processes (OD) are widely applied. Biodegradability of dewatered sewage sludge from OD were comparatively evaluated in digestion and paddy filed experiments. Anaerobic digestion performance was not different under substrate total solids (TS) of 10% and 5%. Under lower temperature conditions of 15-30°C, anaerobic digestion was possible, while biogas production performance was deteriorated. Volatile solids (VS) decomposition ratios under aerobic and anaerobic conditions were 0.6 and 0.4, respectively. A simulated paddy field experiment fed with the digested sludge showed that a higher VS/ TS ratio of the sludge resulted in higher biogas production amount and reaction rate. Biogas production from the digested sludge was lower than that from rice straw, which is the main substrate of methane emission from paddy fields.

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 Desulfurization of anaerobic digestion gas was investigated using photoreactors equipped with sterilizing lamp radiating ultraviolet with a wavelength of 254 nm or ozone lamp with wavelengths of 254 nm and 184 nm. When the digestion gas was injected with oxygen gas, the utilization of ozone lamp removed H₂S more effectively than a combination of sterilizing lamp and TiO₂ thin film. The H₂S removal rate was increased proportionally with an increase in the initial H₂S concentration. Humidifying the digestion gas enhanced the H₂S removal rate. SO₂ as by-product from H₂S degradation was removed from the gas into a separate liquid with high alkalinity from dewatering machine for anaerobically digested sludge. Installing of the photoreactor and gas washer in front of an existing desulfurizer could reduce the amount of desulfurizing reagent by almost half. However, cheaper lamp and photocatalysis responsive to vacuum ultraviolet will be needed for the practical use of photoreactor.

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 The application of thermal pretreatment methods has aroused attention to enhance anaerobic digestion of sewage sludge. Three thermal pretreatment temperatures (50, 70 and 90 °C) were chosen for anaerobic pretreatment of sewage sludge (primary sludge, secondary sludge and mixed primary and secondary sludge). Effect of temperature on sludge characteristics, biogas production potential and energy balance was investigated. The pretreatment results in a higher solubilization of organic matters at higher temperature, especially for that in secondary sludge. The concentrations of soluble CODCr, carbohydrate and protein had increased by 10, 3.5, 74 times, respectively, comparing to those in the secondary sludge without thermal pretreatment. After thermal pretreatment, the methane production potential of primary sludge deteriorated, while that of secondary sludge increased. At 70 °C, the biogas production potential of secondary sludge increased by 15%, comparing to that without pretreatment. The energy balance of anaerobic digestion of sewage sludge shows that in the case of power generation, thermal pretreatment via cogeneration at 70 °C, 90 °C, the power self-sufficiency rate is 60.1, 62.7%, 64.5%, respectively.

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 Collection system of garbage into the sewage treatment plant for anaerobic co-digestion was investigated by a questioner survey in Kanazawa city and Nakanoto town. The results of conjoint analysis of kitchen garbage discharge to the collection site showed that "degree of the garbage separation" was a most important factor for discharge, and "recycling fee" was the next factor. On the other hand, "collection frequency" was a small or minor detail. Frequent collection might not be useful for garbage separation by all citizens. A new recycling system, in which each citizen with environmental awareness brought the separated garbage into a supermarket by themselves, was proposed, and the effects of the system was examined. About 60% of citizen estimated to bring the garbage by receiving benefit in the supermarket.

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 There is a problem that Microcystis bloom often occurs in the Tuchiura-bay, Kasumigaura Lake. Some previous studies indicate there are three processes to occur Microcystis bloom; transportation by the wind; recruitement from the sediment; the vertical miguration, however affection of these processes on Microcysts bloom in the Tuchiura-bay is uncrear. We constructed the ecosystem simulation model to examine the influence of these processes the Microcystis bloom. As the results, the transportation process effected Microcysts bloom because the data by this simulation model added transportation process similar to data of actual decrease of the cell density by diffusion. Meanwhile this model expressived locally and temporary high density of Microcystis cells. It is suggested that the recruitment process has influence on Microcystis bloom, but we need more study with the annual detail data of recruitement from sediment. It is suggested that the vertical migration process has less effect on Microcystis bloom than others.

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 Due to wide and intensive use of antibiotics, antibiotics resistant bacteria (ARB) were often detected from water environment receiving various effluents. We developed a method to estimate the burden of infectious diseases caused by waterborne ARB, which can reflect difficulty in treatment of ARB infection, by applying concept of DALY modified with PK/PD model. Using the developed method, burdens of skin infectious diseases in bathing at beaches and river and in working at paddy fields were estimated, taking existence of ARBs to cefepime and cyprofloxacin into account. For this estimation, new doseresponse models available for skin infection by three species of bacteria (Pseudomonas aeruginosa, Staphylococcus aureus and Group A Streptococci) were proposed. Although it is a rough estimation of based on the small number of samples, the result demonstrates that the existence of ARBs in water environment increased the burden of skin infectious diseases in most exposure scenarios. The maximum increase (7.7 times) of DALY was observed in S. aureus infection via bathing in treated municipal wastewater due to a high rate of its resistance to cefepime. The DALY lost by bathing in a river that does not receive the treated wastewater was significantly lower, indicating that its discharge would pose risk of skin infection to those bathe at the downstream. The DALY lost by the activities in paddy fields using organic fertilizer was much higher than in those using chemical fertilizer due to both higher concentration and resistance rate of the causal bacteria. And the DALY lost by bathing in beaches was low enough even in the swimming season.

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 In order to examine that eDNA abundance could predict abundance of source freshwater insects, we performed meta-barcording analysis of freshwater insects using water environmental DNA (eDNA) in Shigenobu River, Ehime, Japan by Next generation sequencing (NGS) analysis. The eDNA, which is released from various organisms, is one of the most stractiong way to reveal and monitor species diverstity of aquatic animals. Although NGS analysis was employed meta-barcoding analysis for eDNA, a few studies reported the relationship between abundance of freshwater insects and regerated reads generated from NGS. At first, we collected 2L of river water from 12 sites and freshwater insects from 11 sites, 3 times. The water samples were filterd by 0.2 um membrane filter. DNA extraction was performed by Phenol-Chloroform method and ethanol presipitation. Extracted DNAs were purified by DNeasy Blood and Tissue kit (Qiagen) again. Chytochrome Oxidase I reagion was amplified using universal primer for Insects. NGS analysis was performed by MiSeq using v3 reagents (illumina). After quality control and reads screaning using primer sequence, operational taxonomic units (OTU) were clustered. The source animals of OTUs were searched in NCBI data base by BLAST. In result, we detected almost al families, which collected from field, from eDNA. The abudance of freshwater insects was compared with reads abundance. In result, we detected a lot of non-target species (e.g. microorganisms, crastaceans, inland insects). When high number of insect reds, PCR procedure should be improved. The number of freshwater insects showed positive relationship to read abundance from eDNA. It supported that eDNA analysis using NGS predict the abundance of freshwater insects.

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 Polyfluoroalkyl phosphate esters (PAPs) are a group of anthropogenic organic fluorinated compounds which have been widely used in many products. Some researchers pointed out that PAPs are precursors of perfluorocarboxylic acids (PFCAs), which are endocrine disrupting compounds. Main objective of this study was to understand behavior of biodegradation products from PAPs in cosmetics under aerobic condition. For two different biodegradation tests, namely, 1) 8:2diPAPs and 2) a foundation which was labeled “C9-15 fluoroalcohol phosphate” were prepared. As a result, the concentrations of 10 diPAPs decreased during both experiments and they were approximated to first-order reactions. Their half-lives were 6~111 h, and when their molecular weights increased, thier half-lives became longer. Mass of the formed PFOA was 4.0±0.4% of input mass of 8:2diPAP. Not only PFCAs but also some kinds of FTCAs, FTOHs were detected, which seemed to be intermediate products of diPAPs. It was suspected that FTOHs with lower molecular weight (5:2sFTOH, 6:2FTOH, 7:2sFTOH) were diffused into the air by aeration.

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 In this study, we examined the physiological function of nitric oxide (NO) produced in a trace amount in the nitrification process as an influencing factor on nitrous oxide (N₂O) production. Nitrifying bacteria was cultivated with inorganic substrate in the sequencing batch reactor. 200ppm of NO was forcedly ventilated at 20ml/min during the aeration process or stirring process during the cycle. In the system exposed to NO in the aeration process, although an increase in the N₂O conversion rate was confirmed, it was suggested that the direct effect of NO removing the influence of DO and nitrite may decrease N₂O productivity. On the other hand, when NO exposure was performed in the stirring step, a decrease in the N₂O conversion rate was confirmed, it is suggested that NO inhibits the production directly when DO is about 20% or less, and conversely it may be promoted at about 20% or more. In the actual sewage treatment plant, the DO value is often 20% or less, suggesting the possibility of using NO as N₂O production inhibiting factor and management index.

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 Cultivation of aerobic and anaerobic octadecane-degrading microorganisms, as well as prokaryotic community analysis, in Niitsu crude oil artesian area were carried out. For cultivation of the aerobic microorganisms from Niitsu river soil, the bacteria closely related to known alkane-degrading bacteria have been isolated at high frequency, while a small number of bacteria belonging to unclassified taxonomic groups were also isolated. 16S rRNA gene sequences analysis revealed a microbial community with wide variety of prokaryotic taxa in the soil sample. Anaerobic cultivation of microorgaisms in the river sediment were carried out using CSTR fed by the synthetic wastewater with octadecane and acetic acid, resulting in the enrichment of an anaerobic octadecane-degradaing microbial community. Phylogenetic analysis of the microbial community, based on 16S rRNA gene sequences, indicated that microorganisms belonging to Methanosarcina, unclassified Bacteroidales and Paludibacter were frequently detected. PCR-RFLP analysis for alkyl succinate synthase gene (assA) suggests that several types of alkane degrading microorganisms were present in the reactor.

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 Soil samples were collected at 25 points in a 10m×10m highly contaminated area by lead around the old shooting range in Heiwa Park. Also, soil samples were collected vertically from surface to 90cm depth at the center of same area. Surficial and vertical lead profiles were determined.
 The results obtained in this study were summarized as follows.
 1) There is a great variability among obtained data of surface soil concentrations. For surface soils, water-soluble concentrations and contents of lead were much higher than standards at all points.
 2) Soil concentrations of lead collected at the far from walking trail were higher than the near of walking trail. Ratio of water-soluble concentrations or contents of lead to total lead concentration is higher near the walking trail.
 3) The soil collection method of 5 points mixing is mostly effective for the survey of soil contamination at the shooting range.
 4) Lead derived from bullet has been mostly remained until 20cm depth. But water-soluble concentration at 90cm depth exceeds soil standard.
 5) Using sequential extraction procedure, vertical transformation of lead adsorption type to the soil and dynamic behavior of lead in soil are examined.
 6) The dose derived from oral intake of contaminated soil near the walking trail easily exceeds TDI of lead. Potential health risks are still high around the old shooting range.

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 Radiocaesium Interception Potential (RIP) is the intrinsic soil parameter which is defined as the product of the distribution coefficients and the concentration of potassium of the outer solution on condition that Frayed Edge Sites (FES), which are adsorption sites with high selectivity for caesium, are saturated by potassium. Measuring RIP usually needs a lot of time, about 2 weeks. Besides, career-free radiocaesium is usually added in measuring RIP because the amount of adsorbed caesium must be slight. In this paper, at first, a rapid measurement method for RIP is suggested, and RIP values of some soils and clay minerals are measured by both the rapid method and the old one, using career-free radiocaesium. As a result, it is turned out that the new method for RIP leads to overestimate actual RIP values, which is because removal of organic matter by shaking is thought to make caesium to access FES more easily. Moreover, in measuring RIP by the rapid method using not career-free but stable caesium, RIP values when addition of stable caesium is about 1μg is almost as much as the values in addition of career-free caesium.

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 Phenol hydroxylase (PH) is known to degrade trichloroethene (TCE) aerobically. PH gene consists of 6 structural genes, phyZABCDE. Here we selected two different types of PH genes and developed hybrid PH by exchanging structural genes. Firstly two same structural genes were exchanged, and changes on TCE degradability were examined. Resultantly phyZ and phyE were found to have some roles to improve TCE degradation. As a next step, multiple gene exchanges were carried out to examine more detail functions of structural genes. Remarkable improvements of TCE degradability were found in some hybrid PH genes, showing effectiveness of hybrid PH development.

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 The final goal of this research is to develop a simple risk evaluation method for SO₂ erupted from a Mt. Aso, Kyushu Discricts, Japan. As the first step for that, influences of meteorological conditions on behavior of SO₂ were examined by analyzing high SO₂ concentration events that hourly concentration is over 50ppb. The high SO₂ concentration events occurred under the condition that speed of eastern geostrophic wind is about 30m/s and, solar radiation is relatively small or potential temperature gradient is relatively large, or under the condition that eastern geostrophic wind speed is about 5-20m/s with relatively large solar radiation.

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 Coastal erosion is proceeding on the northern coast of Bengkalis Island, Riau Province, Indonesia. Lands where erosion is progressing are primarily peatlands. In the northern coast of Bengkalis Island where erosion speed is high, bog bursts were discovered. In the Meranti Islands, Indonesia, peatland collapses like bog bursts were also seen. Comparing mangrove distribution data and coastal setback rate, it was found that in a place where mangrove did not exist in areas had higher erosion rate. In Riau province, it was found that about 160 ha of land was lost per year by the coastal erosion by the temporal analysis of the LANDSAT images. In addition, it was estimated that 110,000 tons of carbon discharged from the peat which flowed out to the ocean by the bog bursts in northern coast of Bengkalis occurred in December 2014.

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 In Dili, the capital city of Timor-Leste, water pollution is rapidly getting worse. This study aims to reveal a pollutant discharge mechanism and to propose a feasible water quality preservation measure even at the citizen level. Water quality survey and water level survey at 13 wells and 16 streams in four watersheds were conducted. As a result, there were two types of basins. One of which had small groundwater depth throughout the watershed, and another one had larger groundwater depth in the middle- and up-stream. The former had a large outflow which equivalent to that of Japan's excreta or miscellaneous wastewater. The latter had small runoff depth and one order smaller discharged pollutant. In the former case, leaky septic tanks may be filled much faster than expected. In the watershed with small groundwater depth, it is necessary to restrict the use of water in the waterway and to switch the treatment method from which relies on infiltration to a watertight septic tank with regular maintenance.

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 Source of organic pollutant of a moderate-scale lake, Kahokugata located in Japan sea side was examined by the monitoring of water quality in the basin. Increase in organic matter in summer season was due to increase in dissolved organic matter (DOM), and the seasonal variation of DOM could be explained by the seasonal variation of DOM in main inflow rivers. Increase of DOM was recognized in not only downstream but also middlestream of the inflow river, indicating that DOM came from upstream region. Furthermore, dynamics of DOM in a main river was examined by using EEM-PARAFAC analysis. The source of DOM was estimated to be eutrophic pond and rice field studded in mountain side.

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 In many of the world's lakes, the diversity of aquatic plants has collapsed. Dominance by lotus (Nelumbo nucifera) is generally considered to progress organicization of bottom sediment. However, the quantity of lotus-derived refractory organic matter remains unknown. In order to investigate the influence of lotus-derived refractory organic matter on lake sediment characteristics, lotus degradation experiments and field observations of Lake Izunuma were carried out.
 The lotus degradation experiment lasted for 733 d, and the Multi-G model estimated that the residual ratio of particulate organic matter was about 35 and 58 % under aerobic and anaerobic conditions, respectively. In addition, by analyzing long-term lotus degradation and vertical sediment distribution, the present study suggests the possibility of estimating the refractory organic matter has been suggested by using an index of LCFAs/total fatty acid ratio.

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 Katano pointed out that smaller individuals of Opsariichthys platypus and Nipponocypris temminckii occasionally leave the region where Opsariichthys platypus and Candidia temminckii swim in order to avoid attacks by larger individuals of Opsariichthys platypus and Candidia temminckii. Onitsuka pointed out that Opsariichthys platypus avoid Carassius auratus langsdorfii and also that Candidia temminckii avoid Carassius auratus langsdorfii besides Opsariichthys platypus which is larger than 80 mm of body length. However, there are few study of the behavior characteristic of the fish to another fish with different body length. In this study, the behavior characteristics of Opsariichthys platypus that have different body length against Plecoglossus altivelis altivelis in static water was analyzed. It was found that Opsariichthys platypus avoid action against Plecoglossus altivelis altivelis. This tendency becomes small as Opsariichthys platypus body length becomes large.

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 Visual information is one of the factors that fish decides actions, so taking control of their behavior by light has been considered. It is thought that reactions against light are depending on fish species. Inoue et al. pointed out that river fish had a stronger tendency to dicide the swimming position by taking advantage of visual information than oceanic fish. However, effects of light on fish have not been investigated well. In this study, the position of an installed white lamp in the rectangle pool was changed and swimming characteristics of ayu in static water were analysed. It was found that there were few effects on the radius of fish school. On the other hand, the swimming speed increased and ayu got away from the white lamp with the white lamp approaching the bottom in the rectangle pool.

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 In order to form Zostera beds which are similar to natural beds, we tried to restore self-sustaining Zostera beds without transplantation and seeding by backfilling old navigation channel on the coast of Iwakuni, based on the concept of adaptive management. The obejective of this study is to verify the effectiveness of the proposed adaptive management system for autonomous restoration of Zostera bed by backfilling. This project focused on restoration policy, goals, monitoring and evaluations. Mid-term evaluation was done to judge the imposibility to achieve the goals in third year, and then final evaluation was done to judge the degree of success by comparing with natural beds in fifth year. At the backfilled areas, there are not only optimum conditions for Zostera marina but also flowering shoots and growth of Zostera marina, and Z. marina and Z. japonica showed almost the same changes of natural beds within their ranges.
 These results suggest that such self-sustaining beds as natural ones were restored by backfilling old navigation channel, and that this adaptive management was effective for autonomous restoration of Zostera bed.

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 In this study, field experiments were conducted to examine the burst speed of the ice goby, Leucopsarion petersii, a diadromous fish, during its upstream river migration period. The results showed that for ice gobies approximately 4 cm in length, the mean burst speed of the ice goby was the highest under a flow velocity of approximately 40-cm/s, and its value was 90 cm/s, equivalent to a velocity of 21 body lengths per second. The experiments demonstrated that there is a clear relationship between the flow velocity and swimming distance of the ice goby. At flow velocities of ≤ 40 cm/s, ≥ 80% of the ice gobies advanced at least 50 cm. The critical flow velocity at which the ice goby could swim was less than approximately 95 cm/s. This is the same as the burst speed of the ice goby.

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 As urban metabolism facility, the role of municipal solid waste incinerator (MSWI), fecal sludge treatment plant (FSTP) and wastewater treatment plant (WWTP) are important. In this study, we clarified the present situation of MSWI and FSTP cooperation by co-incineration of municipal solid waste (MSW) and dewatered fecal sludge (DFS) and discussed the possibility and potential of further cooperation.
 First, we conducted a questionnaire survey on MSWIs, which have already conducted the co-incineration. From this result, 1. Distance between MSWI and FSTP is within 20 km, 2. Co-incineration ratio of DFS is 14% or less of total input waste to MSWI and 3. Operation ratio is less than 86% of MSWIs capacity, were considered desirable for the cooperation. In addition, the influence of co-incineration on MSWI was considered to be less in terms of the introduction of the equipment for DFS supply to MSWI, composition of exhaust gas from MSWIs and the amount of incinerated ash etc.
 Next, we calculated the maximum amount of DFS to be able to incinerate with MSW in MSWI. 431,000 t/year of the DFS equivalent to 39.3% of the total and annual generation amount of DFS could be additionally co-incinerated with MSW in Japan. It was possible to co-incinerate 174,000 t/year of the DFS equivalent to 15.8% of the total and annual generation amount of the DFS with high feasibility. Finally, we also clarified the area which comparatively has many middle-size MSWIs is suitable to introduce co-incineration.

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 A new method to analyze metal species in municipal solid waste incineration (MSWI) fly ash employing correlation analysis of elemental distribution line profiles was investigated. Titanium species in chelatetreated MSWI fly ash were estimated by this method. After treatments of fly ash by leaching experiments with different solvents, it showed that heavy metals were easily observed on semi-soluble and/or insoluble matrix of fly ash particles by SEM-EDX. Correlation analysis of elemental distribution line profiles showed that crystalline titanium species in fly ash were rutile (TiO₂) and/or perovskite (CaTiO₃). They were incorporated in aluminosilicate phase like gehlenite (Ca₂Al₂SiO₇) and amorphous minerals. In addition, some of non-crystalline titanium seems to combine with aluminosilicate. Correlation analysis of elemental distribution line profiles by SEM-EDX could estimate crystalline and non-crystaline titanium species, which could not be indentifed by XRD analysis.

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 After a controlled (regulated) waste landfill site reaches full capacity, proper site management is still required by law until the site is officially released for other uses. Japan's Waste Management Act requires landfill site owners to set aside adequate funds to pay for site management until that time. However, due to limited information, it is often difficult to estimate the adequate length (years) of the management period, which is crucial to calculate the reserve funds required. If the period ends up being longer than expected, reserve funds might be depleted prematurely. It is therefore important to have a good understanding of the influencing factors. This paper uses multiple regression analysis to examine factors that determine the length of management period of landfill sites for hazardous wastes, based on the results of a survey to municipalities and entities that own landfill sites.

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 Simulation using a mercury environmental fate model is useful and usually required to estimate mercury environmental risk. Because environmental fate of mercury species depends on physical, chemical, biological reactions, models include many parameters. In addition, some parameters like biomagnification factor are reported in several orders of magnitude wide ranges depending on local and/or specific environments. This means that simulations using mercury environmental fate models inevitably include great uncertainty because it is greatly difficult to assess representativeness of parameter values. In this study, uncertainty of model parameters are quantified by evaluating the most appropriate statistical distributions based on Bayesian information criterion. After identification of the best statistical distributions, parameters were discretized. Mercury exposure to human bodies were estimated using a mercury environmental fate model with initial condition of constant mercury load (1.0 g-Hg/yr) to semi-closed wet area. In the case of 10-year mercury emission, mercury exposures were estimated in the 95 percentile range of 8.94x10^-6-53.1 μg-Hg/person/week. When mercury environmental risk is not negligible, its probability was estimated to be 1.78%. Because the new method suggested in this paper will not require representativeness verification of model parameter values and can give easily understandable score on environmental risk concern, it might be useful to support policy makers and promote building public acceptance on mercury problems like final disposal.

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 To enhance removal of HAA precursors in water filtration processes, we produced metal oxide-coated filter media using quatz sand and anthracite coated by iron oxide and manganese oxide. The amounts of iron oxide coated on filter media were significantly greater than those of manganese oxide, and iron oxide coatings produced surfaces with smaller pores and larger specific surface areas. Anthracite attached more metal oxide coating than quartz sand, which offers an advantage for adsorption of HAA precursors. In column filtration experiments, iron oxide-coated sand demonstrated high removal rates of DOC (50 - 70%) and HAAFP (63 - 70%), whereas the removal rates by manganese oxid-coated filter media were low. These results suggested that iron oxide-coated anthracite is the most suitable filter media for removal of HAAFP among the four filter media tested in this study.
 It was also found that the amounts of HAAFP removal were correlated with the amounts of the metal oxides retained in the columns; thus, by increasing the amounts of metal oxide in columns, we can further increase the removal rates of HAAFP.

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 The effect of coagulation and ozonation on biopolymers (high-molecular-weight organic matter derived from living organisms) in drinking water source was investigated through experiments using the following two configuration modes with varied locations for both the treatment processes: Coagulation – Ozonation – Membrane filtration, &, Ozonation – Coagulation – Membrane filtration. For this purpose, the well-used Yodogawa river water was utilized in this study as the raw water for treatment. The obtained results showed, by placing coagulation before ozonation, the concentration of biopolymers could be effectively reduced; and meanwhile, the increasing extent in the concentration of biopolymers caused by followed ozonation treatment could be alleviated. Taking into also consideration the effect of pre-coagulation on lowering ozone doses needed, we could suggest that the configuration mode of Coagulation – Ozonation – Membrane filtration is comparatively more effective than that of Ozonation – Coagulation – Membrane filtration for reduction of biopolymers in the water after treatment.

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 In this study, a novel electrochemical advanced oxidation process (AOP) was proposed and data on design and operating conditions were obtained from batch and continuous experiments. In batch experiments, ozone was stably produced by using SnO₂ anode and the highest current efficiency was about 12 %. In continuous experiments, it was found that effluent concentration of p-CBA decreased and increased with increasing electric current. Moreover, calculated results by a mathematical model assuming two rate-limiting steps (i.e. electrochemical reaction and mass transfer) and gas production were in good agreement with observed results. In addition, energy consumptions were in the range of 2 - 9 kWh/m³ and were comparable to other AOPs in the literature. From these results, it was considered that the proposed electrochemical AOP would be a feasible alternative to former AOPs because of simple operation and structure.

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 To introduce UV-LED to Point-of-Use (POU) water treatment devices at a tap, the risk of microbial photoreactivation is of concern because microorganisms are exposed to visible light immediately after UV disinfection. In this study, UV-LEDs with peak emission at 265 nm, 280 nm and 300 nm were used to inactivate Escherichia coli (E. coli) and subsequent photoreactivation was investigated. The results revealed that inactivation by 265 nm or 280 nm UV-LEDs was efficient equivalently, while 300 nm UV-LED showed lower inactivation efficiency, and comparison of the electrical energy for 3log reduction showed that 280 nm UV-LED was most efficient to inactivate E. coli under the conditions adopted in this study. Meanwhile, regardless of inactivation wavelengths, photoreactivation occurred after 3log reduction and the log inactivation after photoreactivation were 0.51, 0.55 and 0.42log for 265 nm, 280 nm and 300 nm UV-LEDs, respectively. The results of this study indicated fundamental information to apply UV-LED to POU devices.

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 Populations of Anguilla japonica have been decreasing in recent years. The reasons of the population decreasing are overfishing of Anguilla japonica, the deterioration of the river environment and so on. However, in the present circumstances, studies on the ecology of eels and fish ladder for eels mostly haven't advanced. Fish ladders for eels have been designed by considering that not only swimming capacity of eels, but also climbing capacity on a slope. In the present study, an investigation on climbing characteristics of Anguilla japonica was conducted under the condition that grain diameter of boulders in slopes are changed at a constant slope. As a result, it was found that climbing success rate is the maximum at 20mm of major axis. Also, Anguilla japonica climbed while using boulders by serpentine movement, and the averaged climbing speed has been decreasing with the increase of major axis.

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 Experimental study was carried out in the Abashiri Lake where is brackish lake with double-layered formation of freshwater and saltwater. In order to improve the dissolved oxygen of the salt water layer, we examined the water quality change at the time of oxygen supply using by the gas dissolving apparatus (WEP). we collected anearobic water on site and supplying oxygen by WEP in a circulating water tank. It was able to oversaturate dissolve oxygen upto 40 mg/L when pure oxygen gas used.
 Hydrogen sulfide as a toxic substance accumulates in anearobic water of Abashiri lake with a high concentration of 130 mg/L. When supplying oxygen, It is clear that hydrogen sulfide oxidized to solid sulfur which is not harmful. Moreover, It became clear that orthophosphoric acid in water was reduced by contacting with the bottom sludge if anaerobic water completely oxidized with hydrogen sulfide. On the other hand, it was found that oxygen supply for several days does not affect ammonium nitrogen.

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 It is important to keep suitable area by boulder in pool-and-weir fishway to make the migration rates of fish high. In this study, migrating behaviors of Opsariichthys platypus in pool-and-weir fishway were compared with instillation locations of boulders placed on the bottom of pool-and-weir fishway changed. Migration behaviors of Opsariichthys platypus were obtained with the aid of two sets of digital video cameras. It was found that Opsariichthys platypus migrates remarkably uses space between boulders when boulders were placed on the upper bottom in the pool. It is because the velocity of space between boulders is low compared to other space.

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 Sludge dewatering systems are important for sludge recycling and lowering sludge disposal costs in sewage works. Currently, these systems use flocculants for sludge dewatering, but their high cost is problematic. Therefore, several researchers have used medium made of fibers or woodchips as alternatives. In river works, weed growth on riverbanks causes problems due to disposal costs of the grass clippings, amongst others. Grass clippings from public spaces have been attracting attention as a source of biomass in sewage works.
 We assessed the feasibility of using grass clippings to reduce the water content of sewage sludge. Four sludge samples from three treatment plants (A-C) were used to investigate the effect of grass clippings on sludge water content: digestion sludge and concentrated sludge from the standard activated sludge method (A) and concentrated sludge from the oxidation ditch method (B and C). Sludge samples from each plant were mixed with grass clippings in ratios of 0, 10, 30, and 50% to sludge total solids (TS). The content rates of the flocculants were 0, 0.5, 1, and 2% to sludge TS.
 We found that sludge mixed with 1% flocculant and 10% grass clippings reduced sufficiently the water content compared to that without grass clippings. Furthermore, in all sludge samples, sludge mixed with 1% flocculant and 10% grass clippings had a lower disposal cost than that without grass clippings. Therefore this technique can be considered effective and can be applied to both sewage and river works.

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 In this study, we investigated the prediction method of ignition loss and heating value of sewage sludge by thermo gravimetry and differential thermal analysis(TG-DTA). 29 kinds ×2 seasons of dewatered sludge collected from all over Japan were used for this study.
 First, the ignition loss from the Japanese standard method and from the TG curve showed a high correlation of 1: 1, and the average value of the relative error was only 1.02%, so it was strong enough with sufficient accuracy and it was confirmed that ignition loss can be predicted. The DTA curve had two peaks and could be divided into two groups based on the magnitude of these peaks. From multivariate analysis and others, it was shown that this difference mainly comes from the presence or absence of anaerobic digestion. Comparing the lower heating value obtained from the peak area in DTA curve and empirical formula based on ignition loss and the calibration coefficient: K with the lower heating value by the bomb calorimeter and CHN analyzer, a high correlation of these values 1: 1 was roughly obtained and the average of the correlation errors were in the range of 5.17 to 5.20%, it was possible to predict the lower heating value. This simple method can predict the ignition loss and lower heating value simultaneously with less amount of sludge sample.

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 Preparation of calcium phosphate from phosphate in solution from sewage incinerated ash by acid extract was investigated. We focus iron and aluminum ions that need to remove for phosphate recovery, and attempted utilize its. We investigated effect of aluminum gels on phosphate recovery from aluminum containing phosphate solution, and effect of iron ion on phosphate recovery. Recovery efficiency of phosphate in simulated solution was improved by using aluminum gels. By using this method, 90 % of phosphate in extract from sewage incinerated ash and carbonized sewage sludge were recovered. From these results, preparation of calcium phosphate by using aluminum gels is applicable to recover unused phosphate in acid extract from sewage sledges.

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 In this study, we analyzed properties of sewage sludge compost and carried out a test button mushroom (Agaricus bisporus) cultivation on it in order to put sewage sludge to practical application for growing edible mushrooms. The yield from test groups with only sewage sludge compost as the nutrient supplement was much less than that from control groups with cow manure. It means that sewage sludge compost does not contain enough cellulose and potassium for growing mycelia. On the contrary, the yield from test groups with combined use of sewage sludge compost and cow manure was 1.2~1.8 times of that from the control groups. The amount of heavy metals, the main components and amino acids in fruit bodies from all the groups were almost the same. We concluded that sewage sludge compost was applicable to edible mushroom media.

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 The adsorbents which removed arsenic from contaminated water would contain a large amount of arsenic. If the spent adsorbents were dumped into environment without an appropriate treatment, a secondary environmental pollution might be caused by arsenic leaching.
 In this study, the leaching tests with silicic acid solution on the spent magnesium-based adsorbents (MgO, Mg(OH)₂ and two types of MgCO₃) were conducted and the experimental data obtained were examined. From the results, the spent Mg(OH)₂-based and MgCO₃-based adsorbents were found to leached arsenic more easily as silicic acid concentration in liquid is higher. On the other hand, the spent MgO-based adsorbent was found to leach little arsenic and maintain extremely high environmental stability. Therefore, MgO among them was concluded to be the most excellent arsenic adsorbent to be used under the conditions where silicic acid is generated in the leachates from soils, cement-based solidifying materials and so on.

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 We investigated the effect of the water sampling points in a highly turbid river in Southeast Asia on membrane fouling and particle rejection through the microfiltration (MF). The water in the upstream contained more particles larger than 3 μm than that in the downstream. Filtration resistance of the upstream water was smaller than the downstream water due to higher porosity of the cake layer formed. Nevertheless, the particle rejection efficiency through the filtration of the upstream water was by 0.1~1.3 log₁₀ higher than the filtration of the downstream water. Thus, it was suggested that the river water containing larger particles, as that in the upstream, formed thicker cake layer with higher porosity, which brought about lower fouling resistance and higher particle rejection efficiency. We compared the pore size distributions of membranes with the particle size distributions of river waters. It was indicated that the initial stage of filtration resistance was dominated by pore clogging when the particles with comparable sizes to the membrane pores were contained in the feed water, which lead to severe fouling resistance.

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 Separation of oil from produced water is a major issue common to oil-producing countries. During this study, salts (NaCl, NaNO₃, MgCl₂, CaCl₂) were added to simulated produced water (containing emulsified oil) to see the effects of such addition on oil separation. Results indicated that oil-water separation was enhanced as emulsified oil floated to the surface where it could easily be collected. Oil recovery ratio increased with increasing salt concentration, with a maximum oil recovery ratio of 96.3%). The recovery ratio stopped increasing beyond certain salt concentrations. Addition of salts which include divalent cations such as Mg²⁺ and Ca²⁺ indicated high oil recovery at lower salt concentrations than that of monovalent cations such as Na+.
 After oil recovery by salting-out with NaCl, coagulation treatment was conducted for high salinity produced water to remove remaining oil. Results showed that there was minimal differentiation for optimum PAC addition under several salt concentrations (1~20% NaCl). Addition of MgCl₂ and CaCl₂ at 5% concentration, indicated effective treatment, similar to that of NaCl.
 Addition of NaCl to solution containing polymer for enhanced oil recovery, drastically decreased its viscosity. This result indicated that the addition of salt to polymer flood produced water lowers its viscosity, resulting in easier coagulation treatment.
 In order to reduce treatment cost, concentrated brine from reverse osmosis (RO) desalination of saline water (with salt concentrations up to sea water level), could be used instead of aforementioned salts.

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 Towards the achievement for the concept that a sewage treatment plant should serve as a base for circulation of materials and energy in a watershed, the solubilization process for enhanced digestion gas production and the acceptance of excess digestion gas at other sewage treatment plant were studied for model cities with a population of 0.5 million population in combination with material(phosphorus) recovery. AS for the region biomass, jyokaso sludge that introduced all model cities was accepted to a sewage treatment plant. Being conscious of the approach that watershed people concerned were united, some scenario was evaluated by the index of the power self-supply ratio in the watershed and the phosphorus recovery ratio in the watershed. As a result of the evaluation for Matsuyama city, Utsunomiya city, Gifu city, it was found that Matsuyama city had 2points higher energy potential utilization ratio(20%) than Utsunomiya city(18%), so Matsuyama city was the most highest power self-supply ratio in the watershed of 57.4%. From the view point of material recycle, because the Gifu city had already carried out phosphorus recovery from incineration ash, the phosphorus recovery ratio in the watershed was highest (46%) because of the high phosphorus removal (615kg/day; removal ratio; 91%) at the wastewater treatment plants. The quantity of present phosphorus recovery was 307kg/day and was calculated to increase by 7kg/day in acceptance of jyokaso sludge.

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 By the meeting with manufacturers and the questionnaires to municipalities, the actual conditions (types, number of units, operating hours, etc.) of equipments installed in sewage treatment plants were obtained. Several model combinations of different plant scales, treatment processes and equipment patterns were designed and calculated for their power consumption.
 The results showed about 30% reduction in power consumption by renewal of equipment to energy-saving type.
 A study model for reducing power consumption in sewage treatment plants and in a basin based on the power consumption rate obtained in this study was proposed.

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