[in Japanese]

View full abstract

In this paper, the fuzzy dynamic programming model is proposed for the planning of sewerage systems. This model decides both the district and the stage to construct the sewerage systems so as to maximize the total reduction of pollution load during planning period, and it supports the reasonable construction of branch sewers that need a long time. In addition, this model provides the planning scheme with robustness and also evaluates the uncertainty in the future considering the sanitary sewerage flow caused by future population as fuzziness. Furthermore, through the comparative analysis and the case study, the feature of this model is made clear and its availability is shown.

View full abstract

Production of polyhydroxyalkanoates (PHA), a kind of biodegradable plastics, by activated sludge biomass was investigated. Biomass highly capable of producing PHA could be accumulated in a modified anaerobic-aerobic activated sludge process named the microaerobic-aerobic activated sludge process, where small amount of air is supplied to the anaerobic zone. The rate of aeration in the microaerobic phase was found to strongly affect the rate, duration and yield of PHA production by the biomass accumulated in the microaerobic-aerobic process. The observed maximum PHA content was 62% of dry weight of biomass. The monomeric units of the accumulated PHA polymer were mainly 3-hydroxybutyrate and 3-hydroxyvalerate, even though different carbon sources were fed.

View full abstract

This paper evaluates social benefits of accessible waterfront spaces and preserving beaches through the hedonic approach over land prices in the seaside districts of the Osaka Bay Area. Several points to utilize hedonic price method for the social benefits estimation of environmental resources are, firstly, discussed, as well as identifying theoretical backgrounds of the method. One hundred and twenty land price data are, secondly, analyzed after setting the site-attributable environmental variables and district variables to indicate the district-scale environmental characteristics where the land price sample is located. District-wide benefits by the environmental resources are identified and social value of the beach was calculated as a hypothetical case study.

View full abstract

The underground large scale storm-water trunk lines are constructed as storm-water reservoirs for flood control. In this paper, we examined an efficient method of control of the overflow weir that distributes a part of wet weather flow into the large scale trunk line for wet weather flow to reduce the combined sewerage overflow. This overflow weir has two function. One is wet weather flow distribution for flood control and another is wet weather flow distribution for reduction of combined sewerage overflow. There are cases that we can not reserve runoff storm-water, since the large scale trunk line was full before peak amount of the wet weather flow occurs at a large rainfall. There, we made a height of the overflow weir high in the rainy season (for a flood control) and also we made a height of a the weir low in the dry season (for a combined sewage overflow control). If applying this control method, we will be able to be compatible the combined sewage overflow control with the flood control by the underground large scale trunk line for wet weather flow.

View full abstract

The formation process of granule and treatment characteristics were discussed in an Upflow Anaerobic Hybrid Blanket (UAHB) reactor treating a fermentation process wastewater consisting of high sulfate and ammonia. Sulfide toxicity to methanogenesis and TOC/SO₄^2- ratio that was usually used as an index of inhibition to methanogenesis were also examined. The results indicated that the granules could be developed in the process for treating sulfide- and ammonia-rich wastewater, and inhibition caused by sulfide was not occurred when free hydrogen sulfide concentration was less than 200mg/l. Therefore, the UAHB process was shown a better stability for treating the refractory wastewater. The results also showed that total dissolved sulfide concentration had to be considered for inhibition assessing besides TOC/SO₄^2- ratio.

View full abstract

Using disturbed and undisturbed soil columns, solute transport under steady unsaturated moisture flow were studied experimentally and theoretically. Chloride and cobalt were used as tracer materials. Solute transport in unditurbed soil were characterized as follows. (1) Soil moisture flow were simulated almost well by the two-component (mobile-immobile) moisture flow model. (2) Diffusivity of solute transport were more than two times as large as that in disturbed soil columns. (3) Nonequilibrium sorption (diffusion within sorbent matrix) had a significant impact on tailing of breakthrough curves. (4) The fraction of nonequilibrium sorption relative to the total distribution coefficient (Kd2/Kd) were found to be about 1.5 to 4 times as large as that for disturbed soil columns.

View full abstract

The dynamic optimization model with 9 industrial sectors determines the efficient route of the sectoral production by introducing carbon reduction strategies. Under the condition of carbon reduction policy, all sectors diminish gross total products, and the raw material industries and non-manufacturing industries show the high value of elasticity of products respect to the unit carbon reduction. Marginal costs of carbon reduction grow in proportion to the carbon reduction rate. When the indirect carbon emissions in the stage of power generations are counted to be attributable to endusers' responsibilities, total productions in 2020 are recovered by 1.3% compared with those without endusers' charge. These differences of marginal costs are enhanced by the increase of electric demands in the household sector.

View full abstract

We developed enduse-type energy model which is based on the accounting of energy devices. The model can evaluate the relation between the improvements of energy consumption technology and carbon dioxide emission. In this paper, we described the formulation of the model and the projected carbon dioxide emission to 2010 in Japan. The sectors we calculated are residential, commercial, and industrial sectors. Based on the projections, we report that the carbon dioxide emission in 2010 will reach 256.6MtC/a (technology share fixed case), 241.6MtC/a (technology selection case), and 224.7MtC/a (technology selection and electric veneration technology improvement case). Based on the third case, it is possible to establish the national carbon dioxide reduction target, that is stabilizing total carbon dioxide emission at 1990 level by 2010 as for the 3 sectors.

View full abstract

The numerical simulation was carried out for the analysis of seasonal and spatial variation of water quality at Tokyo port which is located at bay head area of Tokyo bay by the water quality model which could calculate concentrations of chlorophyll-a, zooplankton, nitrogen, phosphorus, COD and dissolved oxygen. As the results of the simulation, it was confirmed that chlorophyll-a increased on spring and summer and decreased on autumn and winter, the factors of increase of chlorophyll-a spatially differed, the change of COD was similar to that of chlorophyll-a, and at the area where oxygen-deficient water was formed in summer, dissolved oxygen was consumed remarkably by decomposition of organic matter, consumption by sediment and so on.

View full abstract

The hydrogen production from food processing waste by anaerobic microflora was investigated by using batch culture at 35°C. The change in solid concentration ranging from 2.3 to 9.2% had no significant effects on the final amount of hydrogen production from one unit weight of volatile solids. Maximum hydrogen yield was 0.020m³·kgVS^-1 at a solid concentration of 6.4%. The hydrogen contents of fermentation gas produced were 54 to 87%. Hydrogen was produced during the degradation of soluble sugars in the liquid phase. Acetate, propionate, n-butyrate and ethanol were the main products from fermentation of food processing waste.

View full abstract