Impedance measurements of a bed of Na-type cationic ion-exchange resins packed between two platinum electrodes were carried out under a flow of highly purified water. The high frequency region reflected a charge-discharge process, which changed into a diffusion-limiting process at about 600 Hz, and a discontinuous change with hysteresis in the Cole-Cole plot was observed in a lower frequency. Detailed experiments showed that the frequency of the discontinuity depends on the days that passed before the measurement. As hysteresis is a cooperative phenomenon being strongly associated with a positive feedback mechanism, it is important to investigate water dissociation from the viewpoint of nonequilibrium systems.

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Numerical simulation was developed for improving of desalting efficiency of GDI (Graft De-Ionization). GDI included original-shaped ion exchangers which were synthesized by radiation-induced graft polymerization. Because general EDI (Electro De-Ionization) included mixed ion-exchange resin beads, it is difficult to pack ion-exchange resin beads optimally. GDI have a lot of potential to be improved with improved arrangements of original-shaped ion exchangers. To get better desalting efficiency of GDI, we have developed a new desalting model in which protons and hydroxide ions are generated in the interface of anion exchangers and cation exchangers. Depending on these calculations we study a new type of GDI in which the water dissociation reaction field was arranged into exclusive de ionization compartments. Simulations and experiments concluded that desalting efficiency became high in the new type of GDI(Dw-GDI). In experiments the sodium ion concentration in the de-ionized water in the new type GDI falls to 1/10 of ion concentration in conventional GDI.

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An electrodeionization (EDI) apparatus possesses two functions: the “deionization”, where the ion in treated water is captured, and the “electric-regeneration”, where the electric energy is added. In this paper, the arrangement of ion-exchange resin is investigated in order to find the optimum condition of those two functions. Firstly, the relationship between the electric-regeneration function and the arrangement of ion-exchange resin was obtained. Instead of ion-exchange resin, an anion- and cation-exchange non-woven fabric sheet made of ionexchange fibers was examined to compare the effect of position of the sheets on current/voltage measurement curves. It was evident that the most efficient electric regeneration function was generated in the arrangement of resin where only one “reversed-bias” interface exists. Secondly, it was considered that the distribution condition (arrangement) of the anion- and cation-exchange resins, in which the “deionization function” appeared most effectively, was based on the “mixed-bed” to try to increase the nearest neighbor of both resins maintaining the condition of arrangement of the resin cited above. It was also evident that “thin-layered structure”, in which the anion- and cation-exchange groups were stacked on top of each other perpendicular to the membrane in the desalting chamber, was the most optimum structure. Finally, the way to form this structure in the desalting chamber was discussed.

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Electrodeionization (EDI) is a membrane desalination process that is used in the production of ultrapure water (UPW). Unlike ion-exchange resin demineralization, EDI is a continuous process which does not require acid or caustic regeneration. Also EDI is a fairly simple process which requires little operator attention and little maintenance.
One of the successes of EDI is the high removal ratio of weakly ionized species. Weakly ionized species such as boron and silica break through ion-exchange resin relatively earlier but it is hard to detect the breakthrough by observing conductivity, and moreover, boron monitor and silica monitor are relatively expensive especially for small UPW production. For these reasons, management of leakage of weakly ionized species from ion-exchange resin is always an issue. On the contrary, it does not the case in EDI operation since it can operate continuously.

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EDI system has been widely used for usual D. I. water, boiler feed water, ultrapure water, or water for pharmaceutial production due to chemicals free/continuous operation and easy management.
On this report, the applicability of EDI system for pharmaceuticals production water is evaluated from actual test data. It is concluded that the EDI systems which are durable for hot water sterelization are applicable for this purpose.

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Effective design and operation of electrodeionization process (EDI) require an appropriate simulation model. However, such a model has not been established because of the complexity of the reaction and transport phenomena in the EDI processes. This paper discusses various problems in constructing a simulation model for the EDI processes through an introduction of the researches of the authors and Neumeister et al. The authors' works on the regeneration of ion-exchange resins gave a clue to understand the EDI processes, where regeneration and sorption were simultaneously done. In these works, which were carried out in a relatively large electrodialyzer, some models were first proposed to provide fundamental information for the design of regeneration system of ion exchange resins. The Neumeister et al.'s works were on the development of EDI process for the production of ultrapure water. They proposed a 2D-model to simulate their experimental results. The model, which was based on the rate-determining step of film diffusion, succeeded in explaining the behavior of ions in the EDI process. Their model successfully simplified the complicated phenomena in the process, which suggested a direction for the model construction for the EDI processes. On the basis of the information from the authors' and Neumeister et al.'s works, discussion was done to establishan appropriate model of the EDI processes.

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Continuous Electrodeionization (CEDI) has been used in the microelectronics industries since the beginning of 1990s. The recent field is becoming to require ultrapure water (UPW) at very low concentration of silica and boron. Whereas, it is difficult to remove such weakly ionized substances up to the required level by conventional CEDI. We have developed a CEDI technology, KCDITM-UP, which makes it possible to be new UPW system. This paper will describe the performance and the system advantage compared to the conventional systems.

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I suggested a method to suppress the diffusion of discharged red soil grain in a coral reef near coastal waters by means of a combination of a horizontal outlet and mangrove belts at the river mouth. The invention was composed of a horizontal outlet and some flat steps with a belt of replanted mangrove. Model experiments were planned based on this idea. The many physical phenomena related to this method include admixture, aggregation, sedimentation, diffusion, flow, and waves. Because it was difficult to make the physical model in our laboratory, we considered the qualitative model experiment a practical and easy way to demonstrate the effects of this method.
The fundamental concept for this method was examined and described, and a model was designed with an experimental cistern as a coral reef area. A construct was composed of a horizontal outlet and two step planes of planted mangrove belts. This distorted model should be useful for clarifying the effects of the method under several conditions of tide and discharge from a stream in the next phase. We examined the model experiments for effects on the leaves, branches, trunks and prop roots of a mangrove tree. The experiments were outlined as Froude or Reynolds models. We planned to do the experiments in tap water. Since we observed large differences in diffusion between preliminary experiments with tap water and salt water, real experiments were conducted in tap water containing dissolved salt.
Differences before and afte r setting the model were compared under two tide conditions (Experiment I and Experiment II). One was a low tide that reached the base of the model, and the other was a high tide under which the model was completely submerged. We investigated four cases (from (1) to (4)) in an experimental cistern under these two tide conditions. Case one did not have a model, case two had a horizontal outlet with one flat step, case three had an outlet with two flat steps, and case four was the former model with roughness comparable to mangrove belts. The experimental conditions were similar for all eight experiments.
Although the average amount of trapped deposit in the 49 petri dishes placed on the bottom of the cistern were anticipated to be in the order of (1)≥(2)≥(3)≥(4), it was actually in the order of (1)≥(2)≥(4)≥(3), in experiment I and (3)≥(4)≥(1)≥(2) in experiment II. These results demonstrated that the effects of the model were larger in Experiment I than in Experiment II. Discharged suspension flowed directly into salt water in Experiment II, and did not flow through the inlet and steps.
Experiment I contained a larger amount of trappe d deposit in each region of the model than did Experiment II. For the same experiment, the total amounts of trapped deposit and percentage of it against calculated total value of discharged suspension were larger in the order of (4)≥(3)≥(2), and the amount in Experiment I exceeded that in Experiment II. These results clarified that this method should be useful for the above-stated purpose.

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We will describe the potential usefulness of jellyfish (Aurelia aurita and Chrysaora melanaster), which have increased rapidly in coastal waters, as a fertilizer for vegetable fields. The jellyfish were found, by means of absorptiometry, flame photometry or ICP emission spectroscopy, to have five principal components of fertilizers: nitrogen, phosphorus, potassium, magnesium, and calcium. Concentrations of total nitrogen, total phosphorus, and potassium in Chrysaora melanaster (954, 153, and 667 mg/kg in fresh weight) were 2.8, 3.3, and 1.3 times higher than those in Aurelia aurita (336, 46, and 501 mg/kg), respectively. Concentrations of sodium, potassium, magnesium, and calcium were almost identical to those in seawater. Concentrations of chromium andcadmium in jellyfish were lower than the limit of quantification for ICP emission spectroscopy. Three kinds of vegetables, chingentsuai (a Chinese vegetable), green soybeans, and perilla were cultivated using a suspension of jellyfish as a izer. Jellyfish are inferred to be effective for growth of vegetables, especially chingentsuai.

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Deep ocean water (D. O. W), m eaning water 200 m below the surface, is expected to be a new oceanic resource characterized by cool heat-source, cleanliness and nutrition of plant. Recently in Japan, some prefectural laboratories have been built for researching characteristics of D. O. W, outside of economical studies. These laboratories have been used armored polyethylene pipe as upwelling pipeline with the safety of piping under long term use. A new economical laboratory was constructed using bare hard polyethylene pipe instead of armored polyethylene pipe on solitary island “Shimokoshiki-jima” near the Satsuma Peninsula in Kagoshima prefecture. Using polyethylene pipes they developed 3rd generation products since 1990, getting excellent strength under stressful conditions compared to those of older products. Engineering works of piping were established on board ship that is easier than those of equipment using armored polyethylene pipe because of the lightness of polyethylene, using electric fuse technique for prolongation of pipe and high tolerance for bending, stretching in the field. Economical studies of abalone cultivation on land were presumed to be promotion of an enterprise using D. O. W under economical construction system. Presumed results were fruitful and showed possibilities of commercializing D. O. W.

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