This research was carried out to investigate effects of dredged soil (DS) addition to artificial tidal flat sediment on the emerging benthic ecosystem via this amendment of silt & clay content. Prior to use, DS was treated with poly aluminium chloride (PAC) or a paper sludge-derived agent (PS) for coagulation or solidification for ease of its treatability, whereas dewatered DS was also prepared without any treatment. These DSs were respectively mixed with mountain sand to attain 25% of silt & clay content on the basis of inorganic component, and then the mixtures were used for construction of artificial tidal flats. In the control experiment, natural tidal flat sediment with the same silt & clay content was used. The total wet-weight and number of macrobenthos in the artificial tidal flats were larger than those in the control tidal flat, while polychaetes Capitella sp. and a gastropod Batillaria cumingii were the dominant species in the constructed tidal flats. These results confirmed the feasibility of using DS as an additive of silt and clay to improve benthic ecosystems in constructed tidal flats. In use of DSs treated with PAC and PS, negative impact by these agents was not observed on the number and species of emerging macrobenthos.

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Heterotrophic bacteria isolated from finished and tap water samples were examined for hemolysis activity to determine their virulence factors. Eleven colonies expressing hemolysis activity were identified by partial 16S rDNA sequencing and phenotypic test using Biolog^TM. All eleven strains were identified at the genus level and eight strains were identified at the species level by 16S rDNA sequencing. On the other hand, phenotypic test could identify only two strains at the genus level and four strains at the species level. Furthermore, three of four strains identified at the species level by phenotypic test might have been misidentified. Therefore, it was suggested that phenotypic test is inadequate identifying heterotrophic bacteria in drinking water, whereas 16S rDNA sequencing is a useful identification tool for them. The eleven strains identified have been reported to be food poisoning bacteria or opportunistic pathogens. Since these opportunistic pathogens exist in heterotrophic bacteria, both appropriate water quality control and further study should be continued for safe tap water supply.

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A novel adsorbed phase ozonation process was developed, aiming at the low-cost treatment of Trichloroethylene (TCE)-polluted water. This process primarily consists of two operations: ‘adsorption of TCE’ and ‘regeneration of adsorbent by ozone’. In the step ‘adsorption of TCE’, TCE-polluted water is introduced to a bed packed with ZSM-5 (adsorbent) to realize a selective and high concentration of TCE inside the ZSM-5 owing to its molecular sieve effect and its strong affinity. In the subsequent step (‘regeneration of adsorbent by ozone’), the adsorbed TCE is decomposed by feeding an ozone aqueous solution into the packed bed instead of the TCE-polluted water, resulting in not only the selective decomposition of TCE in the adsorbed phase but also the quick regeneration of ZSM-5. To investigate its effectiveness, a prototype apparatus was designed and its performance was tested to estimate its initial and running costs. Results showed that this process could decompose TCE efficiently and economically.

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In recent years, It has been said that about one-third of the earth's land area is in danger of desertification. Therefore, topsoil, soil nutrients and domestic wastewater are washed away in the hydrosphere. Water pollution, particularly eutrophications has become a serious global problem. Moreover, the problem includes algal proliferation with the release of nutrient salts from the sediment and a decrease in the amount of reservoir water in dams and lakes. The purpose of this paper is to describe the preparation of colloidal-seed pellet for the purification of the hydrosphere. Dredging is an effective method to recover the amount of reservoir water. Sludge and colloidal sediments are considered as waste. However, organic resources are a sourse of nitrogen and phosphorus. The seed pellet was produced from the colloidal sediment of Lake Ezu, and the germination test was carried out with Komatsuna (Brassica campestris) as the material. The germination rate of Komatsuna was 60% or more, and it was effective as a greening material. Therefore, it is suggested that the seed pellet prepared using sediment is one of the useful technologies for the greening of land.

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