Groundwater contamination with hazardous substances such as trichloroethylene, tetrachloroethylene and others have disputed until now. The water Pollution Prevention ACT was revised in June, 1989 (the first year of Heisei) . It has been obliged and started to always exercise surveillance of groundwater from the 1989 fiscal year. It was executed to measure water quality at three hundred fifteen points in Okayama prefecture from the 1989 till the 1994 fiscal year. (30 points; the 1989 fiscal year, 285 points; from the 1989 fiscal year through the 1994 fiscal year.) Forty points were investigated in the 1995 fiscal year in the same way in Okayama Prefectural Institute for Environmental Science and Public Health. The measurement of NO₃-N executed in seventy-two points in Okayama Prefectural Institute for Environmental Science and Public Health in the 1994-1995 fiscal year. The point of measurement was selected in all area in Okayama Prefecture and the points that is densely populated and make use of ground water frequently were selected preferentially. We measured all items as undermentioned in the area of many factories and places of business in Okayama city and Kurashiki city and the environs of a city area. Accoding to the data for the last seven years hazardous substances were not detected and the value of measurement was lower than the estimated standards as provided by the Environmental Agency. The result of measurements was no matter regionally and pointedly. These doesn't produce injurious results. NO₃-N concentration was 0.1-3.4mg/l (the 1994 fiscal year) and 0.2-3.7mg/l (the 1995 fiscal year) and far lower than the drinking water standards (10mg/l) .NO₃-N is concerned in the source of life what is the food production and waste matters treatment. We should provide for the future the way agriculture and lifestyle should adopt. We must take this matter into account seriously.

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Field studies of water quality and phytoplankton community at the stabilization ponds of Osaka North Port Solid Waste Disposal Site (ONPSWDS) were carried out to analyze the relationship between eutrophication and the succession of phytoplankton of the red tide.
Water temperature of the stabilization ponds varied from 6.5°C in winter to 30.0°C in summer. Its water salinity ranged from 27.2 to 29.2. The ponds were found to be hyper-eutrophic because they contained much total nitrogen (5 to 15mg/l) and total phosphorous (0.5 to 2mg/l) .Chlorophyll a concentrations showed a stepwise increase and decrease pattern with values varying at about 20, above 90 and 50, μg/l in the first, second and last step, respectively. pCOD variation followed the same pattern as chlorophyll a concentration with values varying at about 5, above 10 and 10 mg/l. Phytoplankton cell number varied from 10³cells/ml level in the first twenty months of reclamation to 10⁵cells/ml level in the advanced stage of reclamation.The flora of Bacillariophyceae species was abundant and diversified at the earlier stage of reclamation. Other groups such as Flagellata and Chlorophyceae became dominant as reclamation and eutrophication proceeded. It was also observed that when Bacillariophyceae occurred in abundance, Flagellata or Chlorophyceae disappeared or appeared in low number conversely.The increase in Bacillariophyceae cell number was followed by the increase in silica concentration. These findings indicate that silica plays important roles as a thriving compound for Bacillariophyceae.

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Performances of disinfection process were investigated at small domestic wastewater treatment plants (Johkasou) which have an important role for excreta/wastewater treatment in individual houses. As disinfection apparatuses were well maintained by owner or qualified contractor, residual chlorine in effluent was detected in most cases even when wastewater from bathtub was discharged. Disinfection efficiency, however, was not perfect, because there were many cases which residual chlorine and coliform/fecal coliform group were detected together in effluent. It became clear that the concentrations of ammonia nitrogen and nitrite nitrogen in treated water should be at least lower than 10 mg/l to pass the effluent standard of coliform group, 3000 number/ml, with using the current disinfection method.

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Lakes and ponds located around parks, gardens play an important role in recreational and amenity purposes, such as bathing, boating and fishing. However, the contamination of water with microorganisms may be increased when the ecosystem is unbalanced, such as during the summer, and when a lot of animal feces and an excess of food from people. Furthermore, lakes and ponds also store non poisonous water from municipal and agricultural areas and generally accumulates nutrients from municipal, agricultural and animal origins. If the amount of nutrients in the reservoir water is greater than the ability of its self purification, many problems arise, such as aesthetic problems, annoying odors and pollution. It is important to estimate the behavior of microbial indicators in such public water areas.
The removal characteristics of microbial indicators such as fecal coliform, heterotrophic bacteria, using biological filter treatment systems, were evaluated with two kinds of biological filter media, namely ringlace and nonwoven fabric in a polluted pond. The removal of bacteria ranges from 70-80% for both the ringlace and the nonwoven filter media. The reduction of fecal coliforms by predators in the laboratory batch culture was studied. The results show that protozoa have an effect on the reduction of fecal coliforms. The specific growth rates of Opercularia sp. and Tetrahymena sp. are 1.6 and 1.9, respectively.

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The denitrification system was examined under separating from a hydrogen donor by silicon rubber membrane. In this system, the denitrification was accomplished using immobilized denitrifing bacteria on a silicon membrane which was previously treated by glutaraldehyde followed by the treatment of γ-aminopropyl-triethoxysilane. Methanol as a hydrogen donor could be supplied through the membrane, to the denitrifier which exist on the opposite side of the membrane. In case of nitrate solution (23mg-N/l) containing only inorganic elements applied tothis reactor, 90% of the nitrate is removed from the solution at 1.5 hour hydraulic retention time. On the other hand, effects of the bubbling condition on the increasing of organic substances inthe effluent, was not so serious in air bubbling, but there is a large influence in nitrogen gas bubbling. In the actual experiment under aerobic conditions at the sewage treatment plant, the denitrification ability of the membrane reached approximately 0.8g-N/m²/day at above 20°C, but the ability decreased to a quarter at below 15°C.

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Metabolites occurring during bisphenol A (BPA) degradation by a bacterial strain Pseudomonas paucimobilis FJ-4 were identified by using liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC-MS) in order to clarify the BPA metabolic pathway in this strain, resulting in the detection of p-hydroxyacetophenone (p-HAP), p-hydroxybenzaldehyde (p-HBAL), p-hydroxybenzoic acid, 1, 2-bis (4-hydroxyphenyl) -2-propanol, 2, 2-bis (4-hydroxyphenyl) -1-propanol, 2, 3-bis (4-hydroxyphenyl) -1, 2-propanediol, p-hydroxyphenacyl alcohol, 2, 2-bis (4-hydroxyphenyl propanoic acid, and 4, 4-dihydroxyl-α-methylstilbene.
Among them, p-HAP and p-HBAL were main metabolites: 0.8 mole of each was formed when l mole of BPA was removed, after which both metabolites were completely removed. This suggests that BPA is mainly degraded by the cleavage of its propane part to produce p-HAP and p-HBAL, followed by the complete degradation of both metabolites (main pathway) . On the other hand, 2, 3-bis (4-hydroxyphenyl) -1, 2-propanediol and p-hydroxyphenacyl alcohol were accumulated in the culture during BPA degradation though small amounts. As they have structures which cannot be produced by the cleavage of the propane part of BPA, it is suggested that there is another pathway in which the propane part is oxidized without its cleavage (side pathway) . Interestingly, these side pathway metabolites could not removed by the prolonged cultivation, indicating that side pathway seems to produce more recalcitrant metabolites than the original chemical BPA.

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