About the location of the district heating systems for effective use of sewage heat in urban area, Geographic Information Systems as its analyzing tool was developed and the optimized location was discussed in Tokyo based on the analyses of spatial conformity between heat demand and waste heat supply with this GIS. The characteristics of the relationships between demand and supply in each sewage treatment district and geographical influences were also discussed. Large amount of usable heat is shown in sewage treatment districts with long sewer lines, many occasions of heat collection and large amount of heat demand.

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Hydrogen fermentation and COD removal from four kinds of wastewaters, respectively, with concentrated glucose, lactose, sucrose, starch were investigated using a special consortium of anaerobic bacteria in chemostat-type reactors at 35°C. The experiment was conducted by varying the hydraulic retention time (HRT) of the reactor from 3.0 to 24.0 hours in 7 steps. The optimum HRT for hydrogen fermentation of various wastewaters ranged from 6 to 8 hours, at which the biogas produced from each substrate was mainly composed of hydrogen (40%) and carbon dioxide (60%), and hydrogen production yield ranged 9.23-11.0mmol/g-substrate. As a result, the COD removal reached to about 30-40%. The stoichiometric equation and all the kinetic parameters were determined for the hydrogen fermentation of each substrate.

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The effects of COD/S ratio and HRT on sulfate reduction and the characteristics of sucrose degradation in acidogenic phase were investigated by using continuous anaerobic chemostat reactor at 35°C. Sulfate reduction occurred in acidogenic phase even at HRT of 2h and influent sulfate was effectively removed at HRT of 6 to 10h. Sucrose degradation was not inhibited although total sulfide and free-H₂S increased up to 187mg·1^-1, 99mgS·1^-1, respectively. The metabolites, especially H₂, ethanol and lactate production in acidogenesis were significantly influenced by COD/S ratio.

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For the oxidation of low concentrations of NH₄⁺-N, the authers have developed a novel biofilm-membrane reactor, in which biomass is fixed on the surface of rotating membrane disks. The results obtained from this study were summarized as follows: (1) The NH₄⁺-N oxidation efficiency of the biofilm-membrane rector is much higher than that of conventional biofilm reactors. This is explained by the two major reasons, i. e., increasing NH₄⁺-N flux to the biofilm by advection and high rotational speed, and obtaining the treated water from the bottom of the biofilm. (2) Bacterial extracellular polymers seem to have severe influences on the membrane clogging. By adjusting the quantity of fixed biomass, however, the operation could be continued as long as 1000 hours without any cleaning.

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Mt. Sakurajima volcanic SO₂ plume transport process over the Kyushu island was simulated by Lagrangian particle model based on the wind and turbulence fields simulated by a mesoscale numerical model using four-dimensional data assimilation. Mesoscale numerical model simulated well the general wind fields during the passage of high pressure system, and the complicated local wind circulation within the planetary boundary layer.
Numerical results of plume transport process were compared with SO₂ surface and 3-D airborne measurements. It was revealed that simulated 3-D plume behavior explained well the observed SO₂ variation, and the day-time development of PBL played an important role for the transport of the volcanic SO₂ aloft to the surface level.

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The ASMF process was applied to treatment of artificial organic wastewater or artificial incineration ash leachate. The volumetric flux values through ceramic membrane module immersed in the aeration tank were measured under different conditions of aeration and suction mode. The intermittent aeration and suction mode reduced fouling and enabled a simultaneous removal of organic carbon and nitrogen.
The LPRO process could separate not only inorganic substances but also recalcitrant substances, in a leachate pretreated by the ASMF. A new and efficient leachate treatment process might be developed by replacing a conventional process for tertiary treatment by these processes.

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As a case study of life cycle assessment (LCA) of urban infrastructures, the life-cycle energy (LCE) and the lifecycle CO₂ (LC-CO₂) of an urban sewage system in Fukuoka City were analyzed. The estimation covers the construction and the operation of the sewerage pipeline network, waste water treatment plants, and pumping stations. The data derived by input-output analysis are used to determine energy and CO₂ intensities for the construction of the plants and the manufacturing of machinery, while those for plant operation are obtained from actual data. The energy recovered by the use of digestion gas is counted as negative. It is estimated that the construction and the operation account for 55.5% and 44.5% of the total LCE, and 56.4% and 43.6% of the total LC-CO₂, respectively.

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The removal ability of organic pollutants from leachate is numerically studied in crushed stone layer around leachate collection pipes on the bottom of semiaerobic sanitary landfills, which are popular in Japan. It is shown that to exhibit the ability of TOC removal, the pore fraction of the perforated pipes is desirable about 25%, the depth of crushed stone layer should be 0.5-1.0m, and the diameter of the pipes should be 1m in latticework arrangement, or 2m in fish-bones-like arrangement on the conditions that the interval between each of pipes is 20m and design target of TOC removal is 1000mg/L.

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This technical note discusses the primary factors which control the environmental comfortableness in a city center, with emphasis on factors affecting road traffic noise. Information was obtained questionnaires conducted among pedestrians in the city center. The questionnaires included questions about the city center, as well as the residential area of the pedestrians. The results of a comparison of these two areas showed that most people preferred the city center to be an amusement district and their residential area to be close to nature.

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Effects of the moisture content and the chemical nature of solid wastes on their methane production in landfill were investigated using a solid bed incubated at 41°C. The solid-beds were filled with different moisture contents of meat, cabbage, sewage sludge cake, carrot, rice and potato. A simple model contained methane production potential, P, maximum methane production rate, R_m, and lagphase time, λ, was developed to fit the cumulative methane production curve in the batch experiment; and all the parameters in the model for various solid beds were estimated. For each proper solid waste, the lagphase time decreased, but the methanogenic activity increased with the increase of moisture content. The results reflect that the moisture content threshold limit (MS_L) for the methane production in the solid bed was about 60%.

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