Budgets of nitrogen and chlorophyll a, along with macrobenthic fauna were studied in September 2000 and September 2001 at the experimental tidal flat of Hannan Second District, Osaka Bay. The net exchange of nitrogen markedly changed between 2000 and 2001. In September 2000 only five months after its construction, particulate nitrogen, dissolved total nitrogen and total nitrogen were released from the artificial tidal flat to the adjacent waters at a rate of 1.53, 3.86 and 5.39kgN/day, respectively. In contrast, it functioned as a site of sink for nitrogen in relation to the growth of seaweeds and benthic animals in September 2001. As a result, nitrogen uptake by the dominant species of seaweeds attained 2.51kgN/day which accounted for 72% of the total nitrogen fixed at the artificial tidal flat within one day. This suggests that seaweeds play an important rote in the circulation of nitrogenous nutrients at the early stage of the artificial tidal flat of Hannan Second District, Osaka Bay.

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A regression equation, which quantitatively determines the class number of tidelands into four environmental groups was previously developed using the values of chemical assays, the phosphatase activity and ATP biomass of the tideland sediments.
In the present investigation, we applied the equation to Kamo and Mitarai estuary tidelands and analyzed two- and three-dimensional environment structures of these tidelands with a visualization software.
Furthermore, the changes of environmental characteristics of tideland were analyzed using the equation.

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In order to find out effective measures to improve the bay water mass exchange, we carried out hydraulic model experiments. The experiment showed that the dike may change the circulating flow in the basin to improve the residence time of the basin water. The hollow filling around the bay mouth was very effective to strengthen the residual circulation in the bay. It was also highly improve the water mass exchange between the bay and adjacent sea. The effective of this method was also confirmed by t e experiments of more realistical bays selected in the physical model of the Seto Inland Sea.

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The critical water depths of eelgrass bed formation were considered to be related to two phenomena. The leaves and roots of eelgrass in the shallower area of upper critical depth will be cut off and washed away by the wave action; eelgrass in the deeper area of lower critical depth will die by the decline of net photosynthesis. Authors elucidated the relationships between the upper critical depth on sandy substratum and wave conditions (0.2 of critical shields number, 0.6m/s of orbital velocity), and also between the lower critical depth and net photosynthetic rate (monthly net photosynthetic rate=0). Net photosynthetic rate of eelgrass is a useful index for the conservation of coastal environment.

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One of the purpose of environmental restoration in coastal area is to revive an ecosystem in which the material cycle from suspended solid proceeds successfully. In this paper, we investigated bioturbation of sediment by the dominant deposit-feeding species of sea cucumber Stichopus japonicus in coastal sandy mud bottom.
Conclusions are as follows: 1) There were no feeding activity with a rise of water temperature, and concentrations of organic matter did not differ in respect with the presence of sea cucumbers. 2) Moving behavior of S. japonicus had decreased concentrations of reduced sulfide within the depth of 2cm. 3) The effects of bioturbation by S. japonicus acted to increase the number of infaunal bivalves, which may increase the amount of food for S. japonicus.

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The purpose of this study is to develop seawalls for restraint of anoxic water generation over the sea bottom at an enclosed sea area strongly impacted by human activities. A numerical model is used for proposing the shapes of the seawalls with expected functions and the calculated result for the most effective seawall shape is validated by a hydraulic model test. Furthermore effectiveness of the seawall under the temperature stratification field is estimated by the numerical model.

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During the period from 1960s to mid-1970s, problems of water pollution became more widely and severe with rapid economic growth in Japan. A system of Area-wide Total Pollutant Load Control has been established to restrict the quantity of organic pollutants discharged from land areas. COD was used as an indicator and reduction target. In the present study, an aquatic ecosystem model was applied to evaluate the effects of such control on the water quality conservation in Osaka Bay from 1950 to 2020. The results suggest that the load control should be expanded to include not only COD but nitrogen and phosphorus as well, because both nutrients cause internal production of COD.

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A new concept of habitat evaluation procedure for planning and designing the restoration of coastal wetland was discussed. Establishing an independent coastal ecosystem is suggested as a goal of the restoration of coastal nature. Two important concepts were suggested. One is the ecological inter-relations among reed field, tidal flat and seagrass bed. The other is the ecological network among remote coastal wetlands, which is important for the reproduction process of benthos on the larval planktonic stage. Habitat suitability index models for reed, short-necked cram, lugworm and fiddler crab were already developed by authors as the representative organisms of coastal wetland. A basic idea for the model evaluating the ecological relations among these components were presented.

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This paper presents a methodology to determine the best mix of restoration technologies for enclosed coastal seas, and introduces a case of Amagasaki Harbor project as one example of on-site experiments.
The Amagasaki Harbor project is a typical example of the on-site experiments. In this project, field studies of artificial tidal flat, artificial lagoon, floating seaweed bed, and inhabitable quaywall are performed at one site to estimate their environmental restoration efficiencies. The best mix is determined by the results of case studies, such as field surveys, on-site experiments, and numerical simulations.

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The purpose of this paper is to show the region circulation resource recovery system and the procedure in making nutritionally well-balanced feed for domestic animals, using mixture of shochu waste stillage, rice straw and flour. The authors conducted an experiment in making feed for domestic animals by squeezing a mixed sample (shochu waste stillage and rice straw), producing a filtration residue which was left on a filter in squeezing equipment, and adding flour to it. The following results were obtained; 1) it is found that same nutrition component as the feed sold in the market can be produced.2) By adding rice straw to the shochu waste stillage and milling the mixture it is found that fibers from the rice straw act as a fiber membrane and as for that, high SS removal rate was obtained.

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As a measure against decreasing eutrophication in reservoirs with shallow water depth, the reduction of phosphorus loading is one of the effective measures, and in view that, numbers of phosphorus removal facilities have been constructed and they are in operation in Japan. This paper introduces the method of utilization of sludge generated in the water treatment process for reducing phosphorus of river water by which application of the said removal facilities has been confirmed through test plant as effective and stable method, and actual plant was constructed and in operation now.

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The levels of microbial indicators including total coliforms, E. coli and F-specific phages in Tokyo bay and Hiroshima bay were examined. The plaque assay using WG49 as a host strain was proved to be superior for estimation of levels of F-specific phages in marine water. The samples with 4-hour interval were assayed and found that variation within 24 hours for all indicators was small enough compared to those among sampling stations or sampling seasons. All indicators tested were found smallest in the area for raw edible oysters in Hiroshima bay. The levels of F-specific phages were lowest among indicators tested. The coliforms were abundant in the summer season with lower electric conductivity in Tokyo bay, .

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The WTP of the improvement of water pollution caused by domestic wastewater was surveyed by CVM in Indonesia; then, compared with the cost by jokaso system. The total benefit was comparable to the actual payment of Japanese jokaso owners. However, B/C ratio is less than one and it is improbable that they can afford to provide treatment facilities by themselves. The treatment technologies should cost less than 30 percent of the studied system; therefore, further development of low-cost technology is essential. At the same time, environmental education is also important to understand social benefit of environmental conservation. Grant aid may be an effective measure since the benefit is deposited for future cost.

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“MICHI-NO-EKI”, “HACHI-KITA” has been in operation on Route 9 in Hyogo Prefecture since March 1998. A Reservoir Heat Collection System (RHCS) that set two water tanks and a heat collector in underground and is used to control the pavement temperature of parking, which is needed to melt snow and to cool it in summer. Data collected continuously include flow rate of heat carrier fluid, pavement temperatures and temperatures of the fluid in the water tank and the surrounding ground temperatures.
This paper describes the effects of the control method for the pavement temperature on the operation time, the fluid temperature in the water tank and snow melting performance besides the thermal behaviors between the water tank and the surrounding ground.

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A novel model for the kitchen garbage treatment, “crushing with disposer, anaerobic-aerobic degradation in digester, sewerage discharge”, was evaluated in this study. The solubilization and degradation of crushed kitchen garbage were observed in anaerobic wastewater treatment at various temperatures (35°C, 25°C and 13°C) with different addition of nutrients. Both effluents and mass balances of anaerobic-aerobic kitchen garbage treatment were examined at various temperatures with nutrients being added. Experimental results and total cost analysis indicate that the kitchen garbage reduction, the operational safety and economy concerned with the proposed model are optimized at 25°C.

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The method of producing extracellular polymer (ECP) at over loading to enhance the process of granulation was evaluated in lab scale UASB reactor with glucose as substrate. Granules formed within 39 days, following the emergence of ECP and the accumulation of sludge particles. The ECP content increased at every increase of organic loading rate (OLR). The experiment indicated that the increase of OLR, ECP and granulation are closely related to each other. The results showed that the treatment performance could be recovered from the unbalance between foodstuff and biological requirement. Besides, SEM observation revealed that different bacteria species predominated in the granules formed in different running conditions.

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