The way that the global sustainability and the systems of water supply and the sewage works in the 21st century should be discussed. In principle recycle of material resources is possible, while energy recycling is impossible. The development of technology for utilization of energy and resources and the formation of new life style insuring energy saving and resources recycling are indispensable for the formation of our global sustainability. In considering the elevation of life style of developing countries, however, the achievement of that aim still difficult. In the 21st century, the establishment of a new water supply and sewage system should be promoted. The author proposed the effective supply of drinking water of a small quantity and washing water of a large quantity as a countermeasure for serious water resources pollution, and also the re-establishment of a sewage system with a strong concept that does not produce polluted water as much as possible.

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The function to cut the heat flux of solar radiation that a building material made of porus media has is investigated through laboratory experiments. It has been shown that the ratio of latent heat flux due to water evaporation to the radiated energy flux is a unique function of the degree of water saturation of the material. Also the functional form has been given to obtain the equation describing the change in water content in the material. This enables us to water the material using the data of time series of varing radiation and relative humidity.

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The characteristics of solubilization of excess sludge by hydrothermal reaction and the biodegradability of hydrothermally treated sludge were investigated. The effects of the reaction temperature, time and sludge concentration were evaluated. Experimental results suggested that (1) the hydrothermal reaction of the excess sludge was successive reaction, the solubilization of the sludge followed by the gasification, (2) the reaction time was shorten with the temperature increasing, (3) about 85% of the sludge was solubilized above 150°C (0.6 MPa), (4) the depolymerization of the sludge cell was advanced with the temperature increasing, while the biodegradability was slightly increased, (5) the mixture of the hydrothermally treated sludge and the artificial sewage was biologically destructed in about 6 hours by acclimated microorganism.

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We have conducted a survey in three low-income settlements in Mumbai, India in order to make the present state of the solid waste management, dwellers' cognition and factors which influence the choice of waste disposal by dwellers clear. In this paper, the results show that (1) dwellers do not consider the waste as more serious matter than that of water, toilet and drainage, (2) “distance to container” and “cognition of health risk” are important factors, but “outgo”, “education”, “resident period” and “fear of eviction” are not significant. And it is also evaluated that the value which dwellers take cognizance of the health risk is equivalent to about 100m as a distance measure.

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Experimental results presented in previous report was almost reproduced by numerical model, which is employing film flow expression for water movement in gravel layer. The result of real scale numerical experiments carried out by the model showed leachate can be drained completely by capillary barrier if the intensity of leachate reached at the bottom of landfill was below 0.4mm/h. Several effective parameters were altered for examining the drainage capacity. As results, 1) the effectiveness of downdip structure dragging down upper layer can not improve after it exceeds certain depth. 2) more uniform sand can increase drainage capacity. 3) barrier can drain leachate completely as far as infiltrated water is small enough against the amount of water which can decrease potential of upper layer to boundary potential.

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Experiments had been conducted for investigating an applicability of capillary barrier as a leachate drainage system installing at bottom of landfill. Various characteristics, which include type of material, gradient, rainfall intensity, downdip structure, and length of slope, were changed in the experiments and their influences on drainage efficiency were evaluated. As a result, following consequences were obtained. Using high gradient, low rainfall intensity, uniform sand, dragging down upper layer at downdip, and short slope length increases the drainage capacity of capillary barrier. The drainage efficiency depends upon total quantity of water, which multiplied rainfall intensity by slope length. Therefore intensity of leachate reaching at the bottom of landfill should be restrained in practical use.

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A dewatered cake generated from a muddy water treatment process in a construction work is capable of reuse as a vegetative soil base by mixing with organic materials such as fully fermented composts to improve properties of soil to grow plants. The properties of dewatered cakes are much dependent on their generating sources. In order to establish a method for using dewatered cakes to make a vegetative soil base by mixing with organic materials, some initial conditions of such dewatered cakes whose initial properties are different have been investigated. It has been defined that water content of dewatered cakes should be lower than the liquid limit to prevent anaerobic degradation of organic materials, pH should be maintained at lower than 9 to accelerate activity of soil microorganisms. In addition, lower initial water content provides the better property of the amended soil.

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The object of this study is to construct a structural model of citizens' consciousness on recycling behavior. Questionnaires designed to quantitatively grasp factors relevant to the recycling behavior were sent for residents living in Itabashi Ward. Referring a model previously proposed on environmental behavior, the authors designed the hypothetical model on the recycling behavior focusing on the separation by the residents. According to the path analysis, an improved model was proposed and factors that must determine the behavior were clarified. The ratio of participation and the determinant factors in the proposed model were also analyzed by demographic factors. The authors made suggestions on PR for recycling based on the obtained results.

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In order to analyze the processes contributing to the formation of oxygen depleted waters and the subsequent probability of occurrence of hypoxia and anoxia in the inner Hakata Bay, a combined hydrodynamic and eutrophication model was developed. Comparison of yearlong calculation results with monitoring data shows that the model could represent reasonably the important features regulating water quality and dissolved oxygen of the bay. Hypoxia and anoxia are developed in the bottom waters in summer due to the presence of stratification caused by freshwater inflow and meteorological conditions and are most severe during August. The ongoing land reclamation work has insignificant impact on water quality, but it prolongs the duration of hypoxia and anoxia in the bay.

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