The applicability of ozonation combined with electrolysis to removal of persistent organic matter and nitrogen from wastewater was experimentally investigated. Treated night soil was selected as wastewater containing ammonia and organic matter. A cation exchange membrane was used as a solid electrolyte. As a result, 1,4-dioxane as a persistent organic matter and other types of organic matter were rapidly decomposed by hydroxyl radicals generated via cathodic reduction of ozone. Organic matter in treated night soil did not interfere with 1,4-dioxane decomposition. At the anode, free chlorine was electrochemically generated and ammonia nitrogen was finally removed through break point chlorination. Ammonia nitrogen produced via decomposition of organic nitrogen was also removed. The electrolytic current required for ammonia removal was 6.5kC · mmol-NH₃^-1. However, a portion of ammonia and chloramines transformed into nitrate nitrogen by reaction with ozone and hydroxyl radical at the cathodic compartment. Although ammonium ion passed through the cation exchange membrane from the anodic compartment to the cathodic compartment, the ratios of the amount of nitrogen removed to that of ammonia nitrogen reacted were in the range from 0.71 to 0.76. The terminal voltage for electrolysis was successfully decreased using a solid electrolyte.

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The occurrence of sixteen synthetic fragrance materials and nine organic UV filters was investigated in influent, effluent, and excess sludge in 47 sewage treatment plants (STPs) in Japan. Their loads into the STPs and into an aquatic environment via STPs were estimated according to their influent and effluent concentrations. Highest loads in influent into the STPs and effluent into the aquatic environment were 1.79 mg · day^-1 · inch^-1 for homosalate and 0.31 mg · day^-1 · inch^-1 for ethylhexyl methoxy cinnamate (EHMC), respectively. Removal ratios of the fragrance materials and organic UV filters in the STPs were also calculated. The removal ratios varied markedly among compounds. The minimums of the removal ratios were higher than 90 % for benzyl acetate, methyl dihydrojasmonate, octyl salicylate, homosalate, benzyl salicylate, isoamyl-p-methoxycinnamate, and octocrylene, moreover, the lowest removal ratio was approximately 50 % for EHMC. The removal ratios due to adsorption onto the sludge to the total removal ratio were evaluated from the concentrations of compounds in the return sludge. The highest ratio of the removal due to adsorption onto the sludge to the total removal ratio was 40 % for 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclo-penta-[g]-2-benzo-pyrane and 7-acetyl-1,1,3,4,4,6-hexamethyl tetrahydro-naphthalene. Many of the organic UV filters measured were evaluated to be less removed by adsorption because of the markedly higher adsorption to the influent sludge than to the return sludge. Further research on their adsorption and biodegradation in the STPs is required.

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The concentrations and loadings of herbicides were investigated in paddy fields (40.5ha) located around Lake Biwa from May to October in 2005 and 2006. The herbicide losses from the basin determined from the cumulative load from May to July and the application amount determined by the questionnaire method by Japan Agricultural Cooperatives (JA) were estimated in 2005 and 2006, respectively, to be 26.3% and 36.5% for Daimuron, 24.5% and 30.8% for Bomobutide, 21.5% and 18.6% for Simetryn, 15.7% and 9.30% for Benfresate, 9.14% and 11.3% for Pretilachlor, 5.49% and 5.33% for Mefenacet, and 0.32% and 0.84% for Esprocarb, and in 2005 to be 5.52% for Thenylchlor and 4.74% for Cafenstrol. A Simple model was developed to estimate herbicide losses by multiple regression analysis. The specific loss, which is calculated from the total loss and the average discharge on nonrainy days, was used as the criterion variable. The water solubility, Henry's law constant and soil adsorption constant were used as explanatory variables. The most important contributor to herbicide losses is the adsorption constant of soil. The specific losses calculated from the result of multiple regression analysis were consistent with the observed values. The errors between the observed and calculated values were within ± 0.5% for four herbicides and almost ± 1.0% for five herbicides.

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The ability of a typical soil to remove nonionic surfactants from wastewater was investigated. A packed bed using the above soil, with suction filtering of Polyoxyethylenenonylphenylether (NP10,15,20) solution through the packed bed, was prepared. We found that the removal efficiency decreased as the concentration of the NP10 solution is increased and that the Freundlich equation could be used to describe the relationship between the concentration and the removal efficiency in the concentration range of 20-200 ppm. In addition, the removal efficiency tended to decrease as the mole number of added ethyleneoxide (EO) units is increased. This method was found to have a high removal efficiency with regard to wastewater including these solutions of such low concentration that would be discharged into the environment.

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The purpose of this study was to estimate water pollution in minor rivers of a densely inhabited district (DID). The watershed of the rivers studied is a flourishing area for tea production in Kakegawa, Shizuoka, Japan. The quality of river water was observed from Apr. 2001 to Feb. 2007. The results are as follows. The pH values of the rivers ranged from 7.1 to 9.8, because phytoplankton performs photosynthesis. Seasonal changes in BOD and Org-N concentration were particularly pronounced in winter and low in summer, with periodical changes. The net effluent loadings by the basic unit method for T-N and T-P were 605.6 t · y^-1, and 65.70 t · y^-1, respectively. It is estimated that the majority of the T-N and T-P loads came from domestic wastewater loads in DID.

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The present distributions of exotic fishes were investigated in creeks flowing into farmlands around northern Ariake and Yatsushiro Bay, Kyushu Island, Japan. Six exotic species introduced from foreign countries and six exotic species introduced from other internal regions in Japan were captured from several creeks in this area. In particular, Carassius cuvieri, Gambusia affinis, Opsariichthys uncirostris uncirostris, and Lepomis macrochirus were found in 83, 29, 29 and 20 sites, respectively. As other exotic species, Oreochromis niloticus, Ischikauia steenackeri, and Squalidus chankaensis tsuchigae were first recorded from this area. The tendencies on sympatric or allopatric appearances were investigated on the basis of the distributions of each of the exotic and native species. A few exotics such as C. cuvieri, G. affinis, and L. macrochirus, and a few natives such as Pseudorasbora parva and Abbottina rivularis indicated their sympatric appearances. In contrast, the allopatric appearances were indicated between these exotics and several natives. The allopatric tendency was estimated to be attributed to differences in habitat that each species preferred. Although Oryzias latipes preferred the dead water regions similarly to these exotics, this species showed its allopatric appearances with G. affinis and L. macrochirus. The distribution of this species was estimated to be limited by the distributions of these exotics.

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