The characteristics of methane fermentation for treating bean-curd (tofu)-processing wastewater (BCW) containing waste bean curd frying oil were determined. To facilitate the dispersion and degradation of the oil in the wastewater, lipase and two emulsifiers were adopted. Lipase pretreatment accelerated methane fermentation. Three anaerobic digester series were continuously supplied with BCW and operated under the following conditions: Run 1, without lipase pretreatment, thermophilic methane fermentation (55°C); Run 2, with lipase pretreatment, thermophilic methane fermentation; Run 3, with lipase pretreatment, mesophilic methane fermentation (35°C). Triglycerides and long-chain fatty acids (LCFAs) were completely eliminated by lipase pretreatment in the digester (Runs 2 and 3). The calculation of mass balance demonstrated that 70% of the supplied COD_Cr in BCW was eliminated in Run 2, and that 60% of the supplied COD_Cr was converted to methane. However, only 30-40% of the supplied COD_Cr was converted to methane in Run 3 or 1. The analysis of the microbial community structure in the sludge of the three digesters showed that the sulfate-reducing activity in Run 2 was lower and sulfate-reducing population was also smaller than those in Runs 1 and 3. Lipase pretreatment and thermophilic methane fermentation conditions promote the prevalence of LCFA utilizing hydrogen-producing acetogenic bacteria in the sludge of Run 2.

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We studied the characteristics of adsorbents that were prepared by the reaction between crystallized molten slag formed from a melting process and high fatty acid with COO^- ions such as stearic acid and oleic acid. It was confirmed that the amount of oil adsorbed by the adsorbent with stearic acid treatment was larger than that by the adsorbent with oleic acid treatment and the amounts of carbon of the adsorbent and carbonized adsorbent with stearic acid were larger than those of the adsorbents with oleic acid treatment and the adsorbents with stearic acid treatment were more hydrophobic. IR analysis revealed that metallic soap salts such as stearic acid calcium salt and calcium oleate were formed on the surface of the slag. The oil floating on water was not emulsified and sunk under water. The oil-adsorbent agglomerates were not destroyed and the adsorbed oil was not desorbed. The optimum carbonization temperature was 200°C, and when the adsorbent was carbonized at more than 300°C, the oil could not be adsorbed because of carbon reduction. The amounts of adsorbed by the adsorbent and carbonized adsorbent with stearic acid treatment for A-level heavy oil were 0.37ml/g and 0.41ml/g, respectively, and those with oleic acid treatment were 0.18ml/g and 0.38ml/g, respectively. The A-level heavy oil adsorbed by the carbonized adsorbent was easily desorbed by n-hexane and the recovery ratio was approximately 90%.

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The water quality and discharge from a tea field area in Shizuoka were measured daily and the outflow loads of fertilizer components in runoff water estimated. The results are as follows: The amount of nitrogen fertilizer applied was about 1000kg·ha^-1·yr^-1 in the tea field. The annual of T-N effluent load from the tea field was 531kg·ha^-1·yr^-1 and it was 49% of the amount nitrogen fertilizer applied. 97% of the T-N load was composed of the NO₃-N load. Its outflow load, which consisted of storm water, was 51%. The outflow NO₂-N and NH₄-N loads were small in the first half of the investigation period. The T-P outflow load from the tea field was 0.18kg·ha^-1·yr^-1 and the leaching rate was very low, at 0.05%. Most of the phosphate fertilizer was absorbed by the red-yellow soil in the tea field. The average T-P concentration was as low as 0.01 mg·l^-1. However, the T-P concentration was very high after heavy rain in June and September of 2000. Storm water had a T-P outflow load concentration of 64%. The K⁺ outflow load was estimated to be 89kg·ha^-1 for the year. The leaching rate was 14%. The percentage was very low because K⁺ was absorbed by surface soil containing clay minerals. The annual Mg²⁺ and Ca²⁺ outflow loads were 292kg·ha^-1·yr^-1 and 266kg·ha^-1·yr^-1, respectively. Their leaching rates were 63% and 26%, respectively.

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Acid-decomposable organic carbon, proteins, carbohydrates, and lipids were analyzed to identify the organic substances in tideland sediment. Proteins, carbohydrates and lipids were analyzed as amino acids, sugars and fatty acids, respectively, after acid hydrolysis. The following results were obtained from the analyses of the sediments in three tidelands of the Ariake Sea and two tidelands of Hakata Bay.
(1) The percentage of acid-decomposable organic carbon decreased from 47.9% at a 0-10cm depth to 29.9% at a 100-110cm depth in the analysis of sediments in the Ariake tideland; however, the total organic carbon did not change significantly. This result shows that most organic substances were not decomposed to carbon dioxide or methane, but changed to humic acid and kerogen under anaerobic conditions.
(2) The percentage of acid-decomposable organic carbon in sediments (0-10cm) of the Wajiro tideland under aerobic conditions was as high as 48.6%, however, that of the Imazu tideland under anaerobic conditions was as low as 27.5%.
(3) The relative concentrations of amino acids and sugars were almost the same for all sediments; therefore, the protein and carbohydrate structures in the tideland sediments were considered to be similar.

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An economical and simple method of evaluating the impact of water discharged into natural ecosystems was examined using an ecosystem model. An ecosystem model containing medaka and water grass (Egeria densa) was prepared. The three water types used were underground water polluted with volatile organic compounds (VOCs) including trichloroethylene, and diluted with tap water, effluent water that was treated with a biological treatment system; and tap water. Spawning and hatching, mainained hepato-somatic index (HSI), gonac somatic index (GSI) and concentration of vitellogenin (VTG) were monitored. The polluted water, the spawning and hatching of medaka were normal, but the growth of the water grass was restricted although trichloroethylene had been volatilized by pumping air through the water. In contrast, fish that were held in aquarium that contained treated water appeared almost the same as fish bred in tap water, exhibiting no abnormalities in spawning, hatching, or growth. In addition, water grass did not degenerate in such an environment. The areas for improvement of this evaluation method were identified. It is not yet known which types of water are the best controls for the tests.

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Slag has been considered to be a useful biofilm support because of the continual release of minerals in water environments. In this study, the characteristics of a converter slag as a biofilm support were examined from aspects of mineral sources and surface microstructure. Four types of support material: converter slag, the slag melted at 1700°C, basalt, and limestone, were prepared for comparative experiments. The highest density of biomass was found in the converter slag, followed by the melted slag, basalt, and limestone. From the observation of support surface by a scanning electron microscope, it was found that the slag had an intricate microstructure, and basalt and limestone were rather flat. The melting process of slag destroyed the surface microstructure and decreased the adherence of biofilm. However, the process did not change amounts of mineral released from the slag. Results suggest that the surface microstructure of slag, rather than release of mineral from slag, has an important role for the attachment of high-density biomass.

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