Advanced water treatment plants using ozonation are widely used for water treatment or wasetwater treatment facilities.
To explore the feasibility of rapid water quality evaluation technique, experiments were conducted on the application of high-performance liquid chromatography to each process in a treatment plant. The experiments have demonstrated that the water quality can be evaluated in a short time by following the procedures : pretreating a silica-gel-packed colum with sodium sulfate solution, exchanging with pure water, adding sample water, developing with pure water, and obtaining chromatograms that permit simultaneous detection by refractive index and fluorescence.

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We have studied an efficient biological process to treat alkaline wastewater containing sulphide by sulphur bacteria, which was acclimated from activated sludge by thiosulfate and active at neutral pH. The sulphide removal rate of the sulphur bacteria was 135-140 mgS^2-·g^-1 MLVSS·h^-1 at 20°C and fifty times as large as that of activated sludge. The sulphur bacteria finally oxidized sulphide to sulphate. Low water temperature and large sulphide-sludge loading tended to restrain the oxidation of sulphide to sulphate, which brought the accumulation of sulphur except sulphate in the reactor. The biological process by the sulphur bacteria could treat the alkaline wastewater containing sulphide of 300 to 600 mg·l^-1 with HRT 8 hours and the water temperature of 20°C. H₂S emission from the reactor was never observed. The sulphur bacteria could maintain good settleability under FeCl₃ addition and the gross yield coefficient was about 0.14 KgVSS·kgS^2-.

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Light scattering and fluorescence spectrophotometry with radiation of Xe lamp has been investigated to determine continuous water quality. The items of water quality of the determination are Suspended Solids (SS), Nitrate and Nitrite (NO_x-N), Chlorophyll a (Chl. a), Total Organic Carbon (TOC) and Dissolved Organic Carbon (DOC). Continuous and simultaneous determination of these items were conducted by the change of wavelengths for excitation and detection.
Water quality of Lake Biwa was almost constant during monitoring. Averages of errors on monitoring were 0.5mgN·l^-1 in SS, 0.13mgN·l^-1 in NO_x-N, 0.2μg·l^-1 in Chl.a, 0.2mgC·l^-1 in TOC and 0.4mgC·l^-1 in DOC. It was shown that this method responded rapidly to the water quality change by addition of tracers. We could calculate the instant specific growth rates of Microcystis aeruginosa from the continuous change of the Chl.a concentration of the culture. The result showed that M. aeruginosa were increased rapidly in daytime.
This method can determine rapidly water quality because it is not necessary that the samples are pre-treated with such as filtration and addition of reagent.

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Fertilizer which runs off from agricultural watershed was a big problem if the runoff flew into closed water body such as lakes and ponds.
Therefore, many researches were performed to verify the characteristics of behevior for water quality in such the watershed. However, for a case where there is the irrigation intakes from outside of the watershed, it will give great affection on the runoff of the water quality. The authors selected a small agricultural watershed which had irrigation from outside and tophographical chain in the watershed. We have made servey for water quality, rainfall, and runoff water quality from August 3, 1992 till now. As the results we knew irrigation affected greatly on runoff water quality and load. And we know also the tophographical chain decrease T-N concentrations when springing water from upland was again irrigated into lowland paddy fields becase denitrofication occurred there. The sharp decrease in T-N concentration appeared during irrigation period. We knew, then, in order to estimate water quality, LQ equation such as L=aQ^b or L=aQ+b might be difficult to apply. We must think about other ideas where irrigation area spread widely in the watershed.

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For the photo-production of hydrogen using photosynthetic bacterium, Rhodobacter sphae-roides S from the agroindustrial wastes, basic characteristics for hydrogen production were investigated. This strain produced hydrogen gas by nitrogenase enzyme. Nitrogenase of the bacterial strain was relatively loosely inactivated by ammonia in the culture broth. The maximum production of hydrogen (80.3 ml·g cell^-1·h^-1) was observed at 10 klux of light intensity in the pH 7.0±0.1 when malic acid and glutamic acid were used for carbon and nitrogen sources, respectively. Furthermore, hydrogen gas was also produced from glucose, acetate and propionate. The characteristics of photo-hydrogen production by R. sphaeroides S described above might be suitable for application to the anaerobic digestion of agroindustrial wastes accompained with energy production.

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The actual conditions of physical, chemical and biological properties and interrelationship between them in the eutrophic Lake Koyama in Tottori were investigated in 1991 and 1992.
In the both years, the blue-green algae made bloom in early summer (dominantly, Anabaena solitaria) and fall (dominantly, Microcystis wesenbergii). The outbreak of Anabaena might be brought about by low N, especially water soluble N of the water in May and June. Anabaena made the water rich in the non-soluble N. The soluble N of the water increased after the disappearance of Anabaena.
Microcystis became dominant soon after the disappearance of Anabaena. It made bloom in October. It seemed difficult to explain the outbreak of Microcystis by the change in the N concentration of the water. The concentration of P, however, was always enough for the growth of blue-green algae. It was found out that the both blue-green algae suppressed the growth of other algae.
The water temperature became maximum in August and seemed one of the major factors of bloom outbreak. It, however, was also difficult to explain the outbreak of Microcystis by the change in the water temperature.
The peak time of the CFU was close to that of the algae, which suggested the interrelationship between bacteria and algae.

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BOD₅ is an index used for evaluation of water environment and purification function of wastewater treatment facilities. This value indicates bio-chemical oxygen demand consuming by organic matter. However, the BOD₅ measurement is affected by oxygen demand of nitrification and BOD₅ sometimes indicates an abnormal higher value compared with COD_(Mn).
By examining the trend of DO, NO_x-N in incubation bottles and analyzing the change of effluent water quality in wastewater treatment facilities, we obtained some results shown bellow.
1. The nitrification in incubation bottle occurred in initial 2 days for cultivation period of 5 days and observed exponential increase of nitrate.
2. The BOD₅ values of effuents from wastewater treatment facilities often observed larger than the COD_(Mn) value and sometimes take 3 times higher than COD_(Mn) value.
3. The reaction rate of nitrification in incubation bottle was affected by NH₃-N concentration. At the higher concentration of NH₃-N in BOD₅ measurement sample, the rate was in inverse proportion to NH₃-N concentration. At the lower NH₃-N concentration, however, it was in direct proportion to NH₃-N concentration.
In case of being affected by nitrification in BOD₅ measurement, it is difficult to evaluate effluent water quality and purification function of wastewater treatment facilities by effluent BOD₅. So it is necessary to measure the values of ATU-BOD, NH₃-N, NO₂-N, NO₃-N with BOD₅ measurement for biological treatment effluents.

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