In the short-term bioassay using Porphyra yezoensis conchospores, it is basically important to clarify the most appropriate exposure period and end point to evaluate the effects of toxicants on the growth of Porphyra yezoensis conchospores. In this study, short-term bioassays (120 hours) were conducted on copper (Cu) and monochloramine (NH₂Cl), which have different chemical characteristics. Three kinds of end points (survival ratio, germination ratio and growth ratio) at exposure periods every 24 hours were compared to define the most appropriate exposure period and end point.
The minimum LOECs (lowest-observed-effect concentration) for Cu occurred at exposure period of 96 hours in the three kinds of end points. The 96-h LOECs from the survival ratio, the germination ratio and the growth ratio were 0.046 ± 0.026mg Cu·l^-1 (n=5), 0.033 ± 0.027mg Cu·l^-1 (n=5), 0.021 ± 0.019mg Cu·l^-1 (n=5), respectively. The minimum LOECs for NH₂Cl occurred at exposure period of 96 hours in the survival ratio and the growth ratio of 0.093 ± 0.026mg Cl₂·l^-1 (n=5) and 0.038 ± 0.016mg Cl₂·l^-1 (n=5), respectively. The minimum LOEC (0.036 ± 0.000mg Cl₂·l^-1, n=5) for NH₂Cl from the germination ratio occurred at the exposure period of 48 hours.
Therefore, taking into account of the simplicity of bioassay and its sensitivity to toxicants, it is concluded that the most appropriate exposure period and end point is 96 hours for Cu and 48 hours for NH₂Cl judging from the end point of the germination ratio.

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Formation of the sludge by ferrite process was studied by two methods. The one was the approach from oxidation-reduction potential (ORP) change in ferrite reaction process, the other was surface analysis of the sludge by X-ray photoelectron spectroscopy (XPS). The aqueous solution of various Ni ion concentrations as model wastewater was examined.
With increasing Ni ion concentration in original solution, the interval from the beginning of air oxidation to the rapid rising of ORP increased. As compared with the theoretical Ni ratio of the NiFe₂O₄, the experimental result suggests the existence of incomplete Ni ferrite or impure Ni compounds. XPS measurement of sludges formed by ferrite process indicated the existence of Ni(OH)₂ at surface of 1,000mg/dm³-Ni and 2,500mg/dm³-Ni sludges. Hydoroxide was also observed not only at surface but inside particles of 2,500mg/dm³-Ni sludge by the measurement after Xe⁺ sputterring.

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Constituents of oraganic pollutants in leachates from different types of landfill sites were measured by gas chromatograph - mass spectrometry (GC/MS). The leachates contained various volatile and semi-volatile compounds, some of which were regarded as endocrine disrupting chemicals. The leachate from a site filled with more plastic waste contained more micropollutants such as plastic additives than the leachte from a site filled mainly with incinerator ash waste. These micropollutants were decreased in their concentrations along the treatment processes of the leachates. Leachates from least controlled sites where only non hazardous industrial wastes can be dumped legally also contained micropollutants. The changes in the concentration along with the age of the sites were explained by water - octanol partitioning coefficient.

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Field experiments on treatment of human excreta were proceeded using FAT method designed for the use in the alpine zone. The experimental plant is consisted of three parts, that is, a filtration tank(2m³), a contact aeration tank(2m³) and trenches(39m). In this system, human excreata is treated by contact aeration process followed by gravity filtration. The secondary effluent is finally treated by land treatment process by the use of trenches depending on natural purifying ability of soil. Conclusions derived from the experiments can be summarized as follows.
1) SS, BOD, COD, TN and TP contained in raw human excreta were removed about 90, 50, 60, 20 and 50% respectively, through the first treatment process (filtration).
2) BOD, COD, TN and TP contained in the filtrate were removed about 98, 50, 40 and 10%, respectively, through the second treatment process (contact aeration).
3) BOD, COD, TN and TP contained in secondary effluent were removed more than 94, 98, 97 and 99%, respectively, through the third treatment process (land application).
4) Each of BOD, COD, TN and TP contained in raw human excreta was removeed more than 99% through the FAT method consisted of the three treament processes.

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Spectrofluorometry was applied to the detection of micropollutants in tap water. Tap water contains a small quantity of humic substances, such as chlorinated fulvic acids. Survey of tap water in various parts of Japan revealed that raw water from the river in big cities contains relatively large quantities of those substances. A part of fluorescent substances is eliminated in the purification process and it's fluorescence intensity is reduced by chlorination. Fluorescence intensity is also reduced by ozonation process, but changes little by subsequent chlorination. Thus, Ozone/AC (activated carbon) treatment enables us to reduce both fluorescence intensity and a trihalomethane formation potential. Tap waters in Japan show a lower fluorescence intensity, about 1/10 of those of various cities of the world. Although all the fluorescent substances are not always the chlorinated fulvic acid because of different disinfection processes in foreign countries, more attention should be paid to fluorescent substances in tap water.

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The HPLC analysis using gel chromatography with a small amount of dissoluble material sample in tap water has revealed 1) that specific chromatograms of all the dissoluble materials can be obtained by developing tap water with distilled water by use of the RI detector 2) that the concentration of total residue substances C can be obtained from the equation ; C (mg·l^-1) = 5.21 RI (×10^-6) when tap water is measured direct with the RI detector not using a column and 3) that specific chromatograms of fulvic acid and chlorinated fulvic acid that are contained in tap water can be obtained by developing tap water with 0.2mol·l^-1 sodium sulfate solution by use of the FL detecter.

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Much interest has been caused in the garbage recycling system like garbage disposer recently in Japan. To make clear the composition (quality), the discharge, and the loading characteristics of disposer wastewater from typical Japanese household is therefore of much importance, which is also regarded as one of the objectives of this research. Results of our investigation showed that the typical discharge of disposer wastewater was 5l·cap^-1·d^-1, the typical weight was 250g·cap^-1·d^-1, with its composition as vegetables 37%, fruits 30%, meat and seafood 16%, boiled rice 7.3%, used tea leaves 4.4%, and the others 5.3%. A typical garbage was selected and the loading characteristics were investigated. It was clear that the quality of the disposer wastewater was, T-BOD 5,500mg·l^-1, T-COD 5,100mg·l^-1, TOC 3,400mg·l^-1, T-N 270mg·l^-1, T-P 50mg·l^-1, n-Hex 700mg·l^-1, SS 7,100mg·l^-1, VSS 6,500mg·l^-1. Among them the undissolved part occupied about 75%. And the Solid Separate apparatus could reduce about 30% of the disposer wastewater pollution. In addition, it was also suggested that fresh residue exerted a larger influence on the loading disposer wastewater than vegetable. Moreover, disposer wastewater could increase the C/N ratio of domestic wastewater.

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