Co-digestion of sewage sludge and regional organic waste, such as kitchen garbage, is a promising energy recovery method for small facilities. Dewatered sludge is effective for transporting sewage sludge to a centralized wastewater treatment plant. Effects of substrate concentration on mesophilic anaerobic digestion performance and characteristics of digested sludge were investigated by a continuously operated experiment fed with dewatered sludge of approximately 20 (undiluted) – 5% total solids (TS). Substrate concentration less than 10% TS resulted in stable operation with methane production of 0.47 NL/ gVS, viscosity less than 5 dPa·s, and ammonia concentration less than 3, 000 mgN/ L. Substrate concentration greater than 15% TS resulted in digested sludge of more than 10% TS and unstable performance with accumulation of volatile fatty acids.

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 Anaerobic co-digestion of sewage sludge and currently unused biomass has been paid attention. In this study, we focused on the utilization of rice straw. We conducted continuous experiments using pilotscale digesters at a sewage treatment plant for establishment of practical application of the co-digestion technology.
 Rice straw was ground to about 2-3 mm in length, and then pretreated by soaking with water or enzyme-water. Two digesters were fed sewage sludge with (1) water soaked rice straw, (2) enzymewater soaked rice straw. A digester fed sewage sludge alone was operated as a control.
 The digesters were operated under the condition that the mixture ratio of sewage sludge and rice straw were 1:0.5 and 1:0.75 based on TS. When the mixture ratio was 1:0.5, the operation was satisfactory and the specific biogas production (SBP) of rice straw was as high as 342-377 NL/kg-VS. The SBP dropped to 218-242 NL/kg-VS in the mixture ratio of 1:0.75. In both cases, higher SBP was obtained by using enzyme pretreatment.

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 In order to investigate the operating differences by different temperatures as first stage in a temperature phased anaerobic digestion (TPAD), continuous experiments were conducted combining a thermophilic(55°C) first stage and a mesophilic(35°C) second stage, named TM-TPAD, and then combining a hyper-thermophilic(70°C) first stage and a mesophilic(35°C) second stage, named HM-TPAD, focusing on the long-term performance, organic degradation and particle hydrolyzation. The experiments of a single mesophilic(35°C) anaerobic digestion (MAD) were also carried out as comparisons. In this study, the HM-TPAD was operated stably in the long run, achieving a volatile solids (VS) destruction of 51.8%, which was 1.39-folds and 1.16-folds of the values of TM-TPAD and MAD respectively. It can also be concluded that the higher temperature is set to the first stage, the more efficient organic degradation and particle hydrolyzation is obtained for WAS digestion.

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 In 2010, an foot-and-mouth disease epidemic occurred in Miyazaki Prefecture, Japan. Over the period from April to August 2010, almost 290,000 animals were culled and buried. The burial of these carcasses significantly increased people's awareness of environmental contamination. However, little information has been generated on environmental pollution from burial sites. In this study, the characteristics and contamination levels of leachate and gas produced at the burial site were determined using laboratory-scale columns that simulated the burial site. In the case of higher water injection intensity, solubilization of organic substances was initiated in the early stages of the experiment. When the ammonia concentrations in the column decreased to a level suitable for methane fermentation, the amount of gas generated started to increase because of an increase in methane gas production. In the case where water was not injected, a significantly smaller amount of gas was generated except in the early stages of the experiment. The amount of methane gas generated in the column was reduced with the use of sawdust. During the two-year experimental period, the residual carbon concentration was 60%-70% and 90% in the column with water injection and the column without water injection, respectively.

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 This studyinvestigates grate sifting deposition ash, unquenched bottom ash, and water-quenched bottom ash from a mass burn waste-to-energy plant. Various methods were used to determine the characteristics of these ash types and to evaluate the influence of water quenching on bottom ash characteristics, namely visual observation, analysis of particle size distribution, particle thin section analysis, measurement of pH, moisture content, and loss on ignition, bulk chemical analysis, and mineral composition analysis. Results showed that the pH of all samples was in the range of 11.7-12.7. Approximately 70-80 % of samples consisted of CaO, SiO₂, Al₂O₃, and Fe₂O₃. All samples were also enriched with Zn, Cu, Ba, Pb, and Cr, with concentrations higher than 500 mg/kg. Major minerals found in all samples included calcite, quartz, gehlenite, hematite and mayenite. However, physical, chemical, and mineral characteristics of the samples were heterogeneous. There were various indicators of the influence of water quenching on bottom ash characteristics, including differences in particle size distribution, the existence of an unidentified outer layer in water-quenched bottom ash, the decrease in pH, concentrations of CaO, Al₂O₃, Fe₂O₃, Cl, Cu, Ba Pb, Sr and As, and the presence of Friedel's salt in water-quenched bottom ash. Further research on the transformation of bottom ash during the quenching process is needed, as also further study of the mechanisms and functions of the unidentified outer layer.

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 The most severe disasters generate debris and waste in quantities that can overwhelm existing solid waste management facilities, therefore it is stored in the temporary disaster waste pile for further reuse and recycling. Since waste is highly heterogeneous, it is separated into different material and let under meteorological conditions. Due to high moisture content and anaerobic condition inside the pile, wood particles deteriorate quality and along with organic matter even initiate a spontaneous fire. Better understanding of gas behavior inside a disaster waste pile could lead to improve storage method and preserve waste quality and energy respectively. Furthermore, avoiding spontaneous fire would benefit safe storage without additional costs. The objective of this paper is to determine the variation of gas component and temperature in a simulated temporary disaster waste pile in order to enhance methods and condition of a storage site. A column experiment was used to simulate waste pile under different physical conditions. Gas chromatography was utilized to investigate the diffusion behavior of disaster waste pile. The temperature was continuously measured in various waste profiles and the influence on waste storage was examined. Based on disaster waste characteristics, waste material was analyzed under various moisture condition and density. In order to calculate the diffusion coefficient, it was assumed that the gas concentration curve of the diffusion, is obtained as a sum of the contributions of the corresponding single components under different density and moisture content. The paper demonstrates that the density level and waste characteristic could provide an indication of the gas behavior in the waste pile. Results show that diffusion characteristics are varied with solid waste dry density and composition.

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 In previous studies, a system consisting of catch crop cultivation and lactate fermentation was proposed in order to reduce greenhouse gas emission and nitrate infiltration from agricultural field. The system also has aims of recovering nutrient and producing lactate from catch crops to gain profitable products. In this research evaluation of the amount of greenhouse gas emission, nitrogen load to water environment and break-even point of introducing the lactate fermentation system of catch crop were conducted. As a result, increased amount of greenhouse gas emission from the whole system is larger than the decreased amount of N₂O gas emission from agricultural field by catch crop. Most of the nitrogen load from agricultural fields cleaned up by catch crop is discharged as waste water from lactate production process. This means non-point source pollution in the agricultural fields is transformed to point source pollution through the system. Evaluation results showed the system could help to reduce the nitrogen load on water environment using advanced wastewater treatment. From the evaluation of the production cost, we found that nutrients extracting system in the previous stage of lactate fermentation is relatively advantageous than other systems. It was found that the break-even point of the system is greater than 105tDryWeight of catch crop, which means it is greater than 18ha of cultivation area of catch crop.

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 This study was carried out to search for algal strains that grow at a wide range of salinity and has tolerance against ammonium nitrogen and to investigate an anaerobic digestion effluent as a medium for algal culturing. The 5 algal strains of blue-green (strain A), green (strains B, C, D), and diatom (strain E) were examined for salinity tolerance, and the results showed that at a range from 0.2‰ to 30.6‰ salinity did not affect the maximum growth and lipid productivity of strain A. The strain A was Synecococcus sp., and among the 5 strains the specific growth rate of strain A was the highest. Further ammonium tolerance tests were carried out using the modified f/2 medium containing NH₄Cl as the nitrogen source. The strain A grew at a range from 0.9 mM to 57.6 mM of ammonium nitrogen concentration, and its maximum growth attained to be highest at 14.4 mM. Although the maximum growth of strain A at this concentration was higher than that cultured in the normal f/2 medium, nitrate nitrogen was preferable for the strain A than ammonium nitrogen. The strain A grew and produced lipid in the anaerobic digestion effluent diluted with the secondarily treated sewage or seawater; however the anaerobic digestion effluent had the growth suppression factors against the strain A. As a dilution media for the anaerobic digestion effluent, the secondarily treated sewage was better, because it gave more maximum growth and lipid production of strain A.

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 In order to keep the water supply stable in disaster conditions such as the Great East Japan Earthquake, the objective of the present study was to establish a manufacturing technology for high-speed processing of groundwater for domestic use in the case of disaster.
 It was possible by high-speed water flow experiments using weak acid ion-exchange resin, to maintain the treated water pH level and sufficient iron-manganese removal capability for a long period of time. Based on these results, continuous water flow experiments using a combination of weak acid ionexchange resin and UF membrane were conducted with two space velocity (SV) conditions.; medium-SV of 100[1/hr] and high-SV of 200[1/hr].
 As a result, although the total filtration water volume was lower than the target volume by 17% in the medium-SV conditions, an acceptable water quality level was obtained in the resin alone and a satisfactory quality was continuously achieved in the membrane permeate. In the high-SV conditions, total filtration water volume was lower than the target by 34%, but an acceptable water quality was continuously achieved in the membrane permeate.

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 To evaluate the contamination of coastal sediments along the Fongafale Islet, Tuvalu, Central Pacific, a field survey was conducted along the lagoon-side coast, near a densely populated area. Gray and white layers were obtained in the sediment core samples, whereas relatively high acid-volatile sulfide was detected in the gray layer. Considering that the leakage of domestic wastewater from poorly constructed sanitary facilities flows into the coastal lagoon through groundwater during ebb tides, the gray layer was considered to be the runoff pathway of the leaked domestic wastewater. Sediment contamination indices were applied to estimate the contamination level of the sediments. The result shows that heavy metal pollution exists in both colored sediment samples. Then, assuming that an existing septic tank system is used, heavy metal removal method was investigated by operating a 6-L-scale sequencing batch reactor with domestic wastewater as the feed. By this treatment, over 68% removal rate of Pb, Zn, and Cu was achieved, largely owing to the formation of metal-sulfide.

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 This study evaluated a hydroxyapatite synthesized from waste materials to remove fluoride from wastewater of Gero hot spring containing chloride ion with high level. In addition, this study investigated the mechanisms of fluoride removal by the apatite, the suitable condition of removal treatment, and the capability of reuse of apatite. The apatite could remove fluoride from the wastewater of hot spring below the Environmental Quality Standards for Water Pollution in Japan. The capacity of fluoride removal by apatite was higher than those previously reported. Fluoride sorbed on the apatite was chemically stable within pHs of 2 to 8, and 80% of fluoride removed by apatite was attributed to the precipitation of fluorapatite. The optimum treatment conditions of fluoride removal were the addition ratio of 2 g/L and the treatment time of 5 min. However, the reuse of apatite could not result in the fluoride removal below the standard.

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 Chicken Bone Char(CBC) work effectively to remove fluoride ion from solution. It has been reported that the ion exchange between fluoride ion and the hydroxide ion is the dominant reaction in fluoride removal. However, the pH value of the solution changes much less than that expected from the ion exchange reaction between fluoride ion and hydroxide ion after CBC removes fluoride. In the current study, chemical reactions involving in fluoride removal by and CBC was investigated according to an ion budget in the solution during the fluoride removal. It was revieled that when NaF solution was used, CBC removed fluoride by ion exchange with phosphate ion, hydroxide ion followed by the reaction with CO₂ to produce bicarbonate, and an ion exchange with bicarbonate in CBC. On the other hand, when artificial well water containing calcium and magnesium was used, CBC showed a much higher rate in fluoride removal. The formation of calcium chloride and fluoroapatite seemed to acceralate the fluoride removal from the solution.

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 The health impairment caused by ingestion of the arsenic in groundwater is serious especially in Asian areas. Ferrous iron (Fe (II)) is detected in groundwater with arsenic. In order to improve the efficiency of coagulation or adsorption process for arsenic removal, arsenite (As (III)) which is a predominant form in groundwater needs to be oxidized to arsenate (As (V)) as a pretreatment. In this research, arsenite-oxidizing bacteria are enriched from activated sludge, then 16S rRNA gene analysis was conducted. Arsenite oxidization characteristics under different culture conditions (DO, pH, and temperature) were examined and the optimum conditions of pH and temperature were 7 and 30°C, respectively. For the purpose of developing an economical arsenic removal method without an aeration equipment, an oxidizer, and a flocculant, a Down-Flow Hanging Sponge (DHS) reactor with fixed arsenite-oxidizing bacteria was examined. As a result, when the inflow concentrations of As (III) and Fe(II) were 0.5 mg/L and 25 mg/L, respectively, the average arsenic removal efficiency was about 95 %. This efficiency was correspondent to the water quality standard for drinking water value of 0.01 mg/L.

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