The emission amounts of CH₄ and N₂O discharged through each treatment process at a municipal wastewater treatment plant using an activated sludge process as well as their emission characteristics have been examined, taking into consideration such factors as whether the wastewater treatment plant uses nitrification acceleration as well as differences in water temperature between warm and cold seasons. The emission of CH₄ was noticeable from both the aeration tank and the sludge thickener. The former is attributable to the fact that the density of CH₄ in the wastewater influent increased as the compound passed through the primary sedimentation tank, which tends to be anaerobic, then flowed into the aeration tank and was driven out of it by the aeration action. The latter is attributable to the fact that the high-density organic compound had been stored for a long time. Also, it was revealed that the emission of CH₄ is strongly influenced by the water temperature. The emission of N₂O from the aeration tank was remarkable and strongly influenced by whether nitrification was occurred or not, and exponentially increased with the amount of NO₃ generated during aeration process, which was attributable to variations of both microscopic pH and DO inside the activated sludge. The emission amounts of CH₄ and N₂O were estimated to be 6,7×10⁹g and 2.5×10⁸g per year in 1995, respectively, based on this study.

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Microorganisms capable of lysing filamentous bacteria were isolated from activated sludge by screening for their ability to form plaques on an agar plate seeded with cells of Sphaerotilus natans. The supernatant obtained by culturing of those microorganisms lysed S. natans in a liquid culture. Nine strains in the isolated microorganisms revealed very strong lytic activity. The surpernatants were capable of lysing S. natans, Type 021N and Type 1701. However, Type 0041 and Nocardia were not lysed. After purification using column chromatography followed by anion-exchange, gel-filtration and hydroxyapatite chromatography, the lytic substance produced by B. polymyxa showed the highest lytic activity in all of screened bacteria. However, a specific band representing the substance responsible for the lytic activity could not be observed.

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Effective treatment of livestock feces and urine is necessary to prevent surface and ground water from being polluted. In this study, thermophilic oxic process (TOP) was applied to the treatment of swine waste. The proper environment condition for the thermophilic bacteria was investigated. The results were summarized as follows : It was impossible to treat swine waste by TOP. As for the reason, the calorie of swine waste lacked for the calorie of water evaporation and temperature rising. However, it could be treated by adding food oil as an assistant calorie source. When BOD₅ load was 3 kg·m^-3·day^-1, aeration rate was 100l·m^-3·min^-1 and 120ml of food oil was added, 86% of carbon was converted to CO₂ and 98% of water was evaporated in one cycle. ATP concentration and the number of thermophilic bacteria became the highest values under 55% of average water content in one cycle. And in this experiment 7 hours for the duration time of over 60°C in one cycle was suitable for maintaining 55% of average water content. The temperature condition of over 60°C was also very important to increase microbial activity.

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A microbial substance that lyses filamentous bacteria was purified and characterized. It could not be rendered inactive by various enzyme denaturing treatment. The substance had properties similar to those of a biosurfactant that is often produced by B. subtilis. Lysing of filamentous bacteria with synthetic surfactants was also examined. Several synthetic surfactants were found to be capable of lysing filamentous bacteria. Nonionic synthetic surfactants with an HLB of 14 were found to lyse Spaerotilus natans, Type 1701, Thiothrix, Haliscomenobacter, Type 0961 and Type 021N in activated sludges sampled from wastewater treatment plants. Use of the synthetic surfactant to lyse filamentous bacteria was also demonstrated in a continuous-feed aeration tank, and settleability of sludge was improved. The surfactent did not adversely effect floc-forming microorganisms as evidenced by the high rate of TOC removal. The results indicate that synthetic surfactants can be used to prevent filamentous bulking in the activated sludge process.

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Inorganic mercury was detected at a level above the limit of Japanese water quality standard (0.5 μg·l^-1) in well waters in Fukuoka city. Contamination due to industrial waste was not found in this area and the water quality was otherwise good for drinking.
Measurement of mercury gas in the soil have been used to investigate faults in geothermal areas, because such gas is thought to originate from magma along the faults. Although there are no geothermal areas, there are a lot of faults in Fukuoka City. Then, from the estimation which mercury in well water would come from magma, mercury concentration in soil gas and well water were measured in the polluted areas.
The polluted well waters were located along a line straight from north to south on the map and two mercury gas contour lines could be drawn in this area, and high mercury gas concentrations were detected near highly polluted well waters. From the results above, perhaps due to the presence of faults in this area the source of mercury in well water is thought to be mercury gas from magma.

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Volatile organic compounds (VOCs) in the river water and the sea water were analyzed by the purgetrap-gaschromatography-massspectrometric (P&T-GC/MS) method in order to elucidate the characteristics.
Seventeen river water samples and sixteen sea water samplesin Kawasaki city area were collected. Fortyseven kinds of VOCs were identified in the river water and thirtyone kinds of VOCs were identified in the sea water. We found eighteen kinds of alkane and alkene halogenic compounds in the river water and thirteen kinds of alkane and alkene halogenic compounds in the river water.
A Panamanian tanker Diamond Grace, has broken on July 2,1997 in the Tokyo Bay. A total of 1556Kl of crude oil has been spilled into the sea from the tanker. To determine sources of the drifted oils, n-alkanes (C11-C15), benzene and toluene were identified from a drifted oil in the sea and n-alkanes (C7-Cl5), benzene, toluene and xylenein the crude oil.

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