The distribution of polyoxyethylene nonionic surfactants [as iodobismuthate active substances (BIAS)] in river waters in Kanagawa Prefecture (the Tama, the Tsurumi, the Katabira, the Hirasaku, the Sakai, the Hikichi, the Sagami, the Kaname and the Sakawa) from 1978 to 1979 were investigated.
The concentrations of BIAS in 91 samples were below 0.02 - 9.5 mg/l, and about 22% of the whole were below 0.02 mg/l and about 80% of the whole were below 0.20 mg-/l.
The concentrations of BIAS in sea waters (14 samples; the Tokyo Bay and the Sagami Bay) were below 0.02 mg/l.
The mean value of BIAS was 1.5 mg/l for the R. Katabira and it was higher than that of the other rivers.
Water pollution of the R. Katabira was strongly effected by the textile industrial wastes.
The correlations between BIAS and the other water quality indexes in river waters were discussed.

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An experimental pilot plant study has been carried out for about two years. It is concluded that single sludge intermittent aeration process should be feasible for the denitrification of night soil, and has following advantages; 1) Construction and running cost should be reduced. 2) 98% of nitrogen is removed by the condition of five times diluted waters. 3) Carbonaceos source applied for denitrification stage is reduced. 4) The pH value is maintained 6.7 to 7.6 without using alkali by the condition of five times dilution with water.

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Adsorption of linear alkylbenzene sulfonate (LAS) by activated sludge has been studied, and the following results are obtained;
(1) The adsorption of LAS attained equilibrium in 1 hour.
(2) No effect of temperature on the adsorption of LAS was observed.
(3) The adsorption of LAS took place according to Freundlich's isotherm.
(4) The adsorption of LAS homologues isomers depended on the structure of hydrophobic group of LAS. That is, the longer the alkyl chain length and the shorter the distance of phenyl group from the far end of alkyl chain, the adsorption of these surfactants became increasing. This tendency was consistent with the biodedgradability of LAS homologues/isomers.
(5) The minus charge of activated sludge decreased with lowering of pH, and its isoelectric point was observed at pH 3.0.
(6) Furthermore, the adsorption of LAS increased with decreasing of minus charge of activated sludge, and then became constant below isoelectric point.
From these results, it was concluded that the adsorption of LAS by activated sludge depended on the structure of hydrophobic group of LAS.

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Reaction mechanism of humic acids of different origin with chlorine was investigated.
Two kinds of humic acids showed the different patterns of formation of chloroform and the other chlorinated substances under various conditions for chlorination. High performance liquid chromatography, Sephadex gel chromato graphy and infrared spectrophotometry of humic acid and chlorinated one demonstrated that these differences are derived from the different functional groups in a molecule of humic acid, and, in addition, humic acid is decomposed to lower molecular weight substances having molecular weight of about several thousand and higher chloroform formation potential.

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A procedure for the determination of nitrate in eutrophic freshwater and sea water is presented. Before the determination of nitrate in sea water, magnesium and calcium were removed by precipitation as hydroxides. The nitrite initially present in the sample solutions was decomposed with ammonium amidesulfate under acidic condition. Then nitrate was reduced to nitrite with hydrazine sulfate under an alkline condition (pH 12.3) catalyzed by Cu²⁺for 30 min at 33°C. Zn was also added to the catalyst solution at a concentration in excess of the Cu²⁺ (Cu²⁺ : Zn²⁺=1 : 200) to saturate the complexing capacity of any water sample and to minimize the complexing of cupric ions. Nitrite thus produced was measured spectrophotometrically following a diazotization and coupling reaction.
In the above conditions, the applicable range is 0.05-0.7 mg/l as nitrate nitrogen. Variations in salinity have no significant effect up to 40 parts per thousand. In natural water samples interferences of soluble organic substances were eliminated by addition of Zn²⁺ to the Cu²⁺ catalyst solution and the proposed method was compared favourably with the automated copperized cadmium column technique for freshwater and sea water samples containing 0.1-1.7 mg/l as nitrate nitrogen.

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Activated sludge flocs were completely disrupted employing homogenization and sonication, and the total number of bacteria in activated sludges was microscopically counted with a Thoma blood corpuscle counting chamber after stain by methylene blue. In four different types of activated sludges, total numbers of bacteria were well correlated with MLVSS rather than MLSS, and the correlation coefficient was 0.99. The total number of bacteria per 1 mg MLSS was counted 1.02×10⁹ and that of bacteria per 1 mg MLVSS counted 1.32×10⁹, resulted in both numbers showing 10 to 100 times greater than the numbers of vial bacteria which were reported in many papers. The total number of bacteria increased according as an increase of SRT with which the activated sludge process was controlled in the bench scale plants, It, however, indi-cated to reach an upper limited value. Both numbers of bacteria per 1 mg MLSS and MLVSS showed a tendency to decrease when the process was controlled with longer SRT.

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An analytical method for benzo (a) pyrene (B (a) P) in sediment was devised by using high performance liquid chromatography with fluorescent detection. Sample was freeze-dried, extracted into acetonitrile with ultra-sonic vibration and analysed by reverse phase chromatography. Detection was made with fluorescence detector by observing emission intensity at 406nm after the excitation at 366nm. A surveilance in Kawasaki Port revealed that B (a) P concentration is high in the vicinity of petroleum chemistry industries. It was also noticed that some kind of heavy metals such as copper and zink are correlated to B (a) P level in the sediment.

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