Seasonal characteristics of the spatial distributions of NO₃-N, NH₄-N and PO₄-P in Tokyo Bay were revealed by applying statistical methods to the monitoring data obtained at 41 observation points every month from April 1985 to March 1990.
In the surface layer, the concentrations of the three nutrients were always high near the mouths of the big rivers which are located at the head and the west coast of the bay, and those were low at the mouth of the bay. The difference between the concentrations of NO₃-N at the mouths of the rivers and those at the offing was relatively larger during spring to autumn comparing with that in winter, and difference in NH₄-N was largest in spring. At the offing of the mouth of the R. Tama and at the southwestern part of the bay, the concentration of PO₄-P bacame lower comparing with those at their circumferences.
On the other hand, in the bottom layer, the concentration of the three nutrients were always high at the northern part of the bay where the Shallows lie. The concentrations of NO₃-N and NH₄-N in summer and in autumn were lower than those in the other seasons. That of PO₄-P took its peak in August and in September, and it was higher than that in the surface layer.

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Factors affecting the performance of ammonia removal by ozone under the existence of bromide were investigated. Under the existence of bromide, both the reactions of nitrogen gas formation (TN removal) and nitrate formation were found to be in near zero-order kinetics with respect to ammonia concentration. The nitrogen gas formation rate increased linearly with the increase of initial bromide concentration, while the nitrate formation rate was decreased by the increase of initial bromide concentration. In addition to the initial bromide concentration, the ratio of Br to N (NH₄⁺-N) was also found to be an important parameter in controlling nitrate formation : nitrate formation rate decreased with increasing the Br/N ratio. In the pH range of 4 to 9, the nitrate formation rate increased with the increase of pH, while a maximum nitrogen gas formation rate existed around pH 6. From the view points of reaction rate and nitrate formation control, the optimum pH value was around 6. The nitrogen gas formation rate increased by 50% when temperature was increased from 13 to 39°C, while the nitrate formation rate remained constant. ORP (oxidation-reduction potential) showed an instant response when ammonia was completely removed, and therefore was considered to be an effective parameter for process control.

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Effect of soluble microbial products (SMP) on permeate flux in a cross-flow type ultrafiltration was investigated.
Synthetic wastewater (phenol) was continuously treated by an activated sludge process incorporating membrane solid-liquid separation. Hydraulic retention times and the sludge concentrations of the reactor were kept at 12 hours and 5,000 mg VSS·l^-1, respectively. At certain intervals, batch filtration tests using mixed liquor of the reactor were conducted to investigate the mechanism of membrane fouling. The permeate flux dropped gradually, due to increase of SMP concentrations and of fouling mass adhered onto the membrane surface.
Batch phenol-degradation reactor and aerobic sludge digestion reactor were operated, and batch filtration tests were conducted to examine which type of SMP has more important role in flux drop. Higher flux drop was observed when the mixed liquor of the sludge digestion reactor was tested at a same level TOC concentrations of SMP. It was found by gel-chromatogram that high-molecular-weight SMP was dominant in the sludge digestion reactor. The results suggest that SMP_e (SMP resulted from endogenous cell decomposition) has more significant effect on flux drop.

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Denitrification of nitrified wastewater was investigated by using a bioelectro reactor which consisted of immobilized denitrifying bacteria electrode as cathode and carbon electrode as anode.
Experiments were performed to investigate the effects of electric current, influent nitrate concentration, HRT and ORP on the denitrification rate, nitrite production and hydrogen utilization.
The denitrification rate and hydrogen utilization were varied with mol ratio (λ) of hydrogen and nitrate which were supplied to the bio-electro reactor, and those muximum values were observed at λ=1.4. Nitrate remained under λ=1.4 in the effluent, and residual hydrogen occurred upper λ=1.4.
The nitrite production was not effected by change of λ value and ORP and DO have to control in the proper values because nitrite production was enhanced in the higher value ranges of ORP and DO.

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In the Inland Sea of Japan, with increasing the inflow of nitrogen and phosphorus phytoplankton proliferated, resulting in deterioration of water quality. The water area what is called eutrophication is progressing was investigated.
In 1995, red tide appearance was observed in Okayama prefecture. Damage was not done to fishery but it is necessary to pay attention. Skeletonema costatum, it's phytoplankton was observed in sea water of a bathing resort in Okayama Prefecture. COD was increased to 3.1 (mg·l^-1).
Kojima lake is a man-made fresh-water lake and values of water quality parameters for instance COD, T-N, T-P, are two times as much as environmental standards. During summer in 1995, fresh waterred tide was observed and characterized by the appearance of Aphanocapsa rivularis and Anabaena spiroides at the point of Himon in Kojima Lake. And it needs to survey the mechanism of burst appearance.

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