Various mutagens and carcinogens are formed during the chlorine disinfection of raw drinking water. Among them, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), exhibits a high mutagenic activity against Salmonella typhimurium TA100 without S9 mix, which is comparable to aflatoxin B₁. Recently, it has been demonstrated that MX induces stomach tumor to rats in the 2-stage carcinogenicity test using N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). In this review, we summarize the distribution of MX in several water samples including drinking water and its chemical, biological and genotoxic properties.

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We propose a useful exposure analysis technique based on the analytical framework linking multivariable analysis and regression analysis through the classification of monitoring points using observed concentrations of 4-nonylphenol, some surrogate indexes for emission quantity and basin characteristics in Japan. In order to accomplish this work, we constructed a nationwide basin database from data of chemical emission and watershed landscape. By cross tabulation and discriminant analysis using three variables, namely, pollutant load factor, sewage treatment factor and scaling factor, we classified the monitoring sites of 4-nonylphenol concentration into five groups: ‘emission from manufacturing industry’, ‘emission from wastewater treatment plant’, ‘emission from unsewered area’, ‘dilution and removal’, and ‘the others’. Then, we employed the principal component analysis with pollutant load factor, sewage treatment factor, scaling factor, population density and urban activity to characterize the classification groups. We obtained regression equations that explained 4-nonylphenol concentrations within a confidential interval of 10 percent for samples of the ‘emission from manufacturing industry’ group. This method can be utilized for the preliminary exposure analysis of chemicals based on their basin characteristics.

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Anaerobic ammonium removal was observed in batch tests using a denitrifying sludge from an industrial wastewater treatment plant and an intermittent nitrifying-denitrifying sludge from a mixed piggery domestic wastewater treatment plant after 92 and 84 days, respectively. The simultaneous removals of ammonium and nitrite with nitrate production at ratios corresponding to that reported for the Anammox process were observed. Their specific ammonium conversion rates following one year of incubation after the first detection were 0.260 and 0.281 g N·g protein-d^-1, respectively. Using 16S rDNA sequence analysis, one of the sludges was confirmed to have an organism with a 99.2% similarity to the first reported Anammox bacterium, a deeply branching planctomycete, Candidatus Brocadia anammoxidans. In addition, the other sludge contained an organism with a 98.9% similarity to the Anammox planctomycete, Candidatus Kuenenia stuttgartiensis.

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A cylindrical-anode wetted-wall corona discharge reactor was used to degrade phenol in water. Acetic acid and some aromatic intermediates, such as resorcinol, pyrocatechol, hydroxinon, and 1,4-benzoquinone, were detected as by-products. From the concentration change with time of these by-products, the aromatic by-products were considered to be converted to relatively stable acetic acid before the total carbons were mineralized. By using the present method, TOC and COD were reduced to negligible levels. The energy efficiency of this reactor was higher than that of the previous plate-anode reactor, and also than that of other reported physico chemical techniques such as pulsed discharge or photocatalysis.

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In Kuriyama Town, Hokkaido, slags that contained a high concentration of hexavalent chromium(Cr(VI))from a chromium factory was disposed in landfills, both inside and outside the town. Because leachate from landfills was caused environmental problems, we have carried out water quality surveys twice at the rivers and wastewater pipes of Kuriyama Town in 1971. It was found that although many sites had no concentration or relatively low concentration of Cr(VI), the rest of the sites had a high concentration of Cr(VI). The Cr(VI) concentration was lowered because the large-scale landfills were covered with a reducing substance, asphalt, and the small-scale landfills, which were used by households, was managed according to sewage guidelines. The ratio of Cr(VI) found in total Cr varied at different locations depending on whether a reducing substance was present or not. In most cases, Cr(VI) in the rivers was not detected when irrigation water flowed into the river. The Cr(VI) volume discharged from the Tagami landfill was calculated to be approximately 82ton and 27% of content Cr(VI). If other landfills were included, it was estimated that water-discharged Cr(VI) could be more than 100t.

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This research analyzes the responses of residents to a questionnaire regarding watershed environment issues. The questionnaire was implemented by the government of Gifu Prefecture. The purpose of the questionnaire and analyses was to understand not only the residents' perceptions of issues and problems, but also their ideas for policies and countermeasures. To begin with, the replies to the questionnaire were analyzed for statistical occurrence of key words. These key words are listed, and shown in a scatter plot diagram on the basis of a correspondence analysis. The results show that residents are concerned with three major issues; water quality, water quantity, and desirable relationships among people and the water. Based on these results, several watershed-management recommendations are presented to the Prefectural government. These include clarification of objectives, integration or consolidation of responsibility for water management policy in the prefecture, and closer cooperation and information-exchange among government and residents.

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