The present study was carried out to elucidate the effects of storage (freezing and thawing) of polluted water samples on concentration of nutrients and organic matters.
Water sample was collected on 17th May, 1978 at Nogawa River and filtered by Whatman GF/C filters. Concentration of nutrients and organic constituents was immediately analysed for a part of the filtered sample and the residue was stored in a deep-freezer at -20°C. When the frozen sample was thawed at room temperature, suspended particles were observed in the thawed sample. Chemical constituents were determined for filtered and unfiltered samples. The process of freezing and thawing was repeated three times during a series of the present study.
Little differences in concentration of nutrients were observed in unfrozen and frozen samples. It is considered that there is no effect of suspended particles formed during freezing and thawing on determination of nutrient concentration. The amount of suspended organic particles formed during these processes was about 4 mgC/l.
Changes in molecular weight distribution of dissolved organic matter were observed during the process of freezing and thawing. The amount of low-molecular weight fractions (molecular weight less than 500) did not change remarkably and constituted about 20% of the total dissolved organic carbon. However, macromolecular organic fractions (molecular weight greater than 100000), especially proteinaceous materials, were found to decrease after the process of freezing and thawing. Thus, it is considered that high molecular weight fractions are major constituents of suspended particles formed during freezing and thawing processes.

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The operation of wastewater treatment on the rotating biological contactor was simulated by a mathematical model. According to this model, effects of daily-fluctuation of the influent load on the effluent quality of water were quantitatively analysed through illustrative calculations and their comparisons with the experimental data, previously reported.
Under a constant influent load, the hydraulic retention time in the contactor θ does not affect on the effluent BOD.
When there exists daily-fluctuation in the influent load, the weighted average effluent BOD is usually higher than its value given under the condition of the averaged constant load. The increase in θ results in relaxation of the effect of daily-fluctuation on the effluent BOD as well as decrease in its weighted average value in some extent.
Use of an equalization tank in advance to the contactor will be more efficient to accomplish the same purposes. Under a constant liquid flow condition, the weighted average effluent BOD takes a constant value, independent of the concentration fluctuation of influent and the value of θ.

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For the characterization of advanced wastewater treatment process, it is not enough to express the water quality as BOD or COD which is the overall index of organic pollution. The treatability of organic wastewater has been characterized by the, molecular weight distribution and organic analysis. We here tried to introduce hydrophile-hydrophobic properties of organicfor evaluation of biodegradability and activated carbon adsorbability.
The biodegradability and activated carbon adsorbability were tested on 64 compounds based on BOD analysis and adsorption isotherm respectively. The relation to the hydrophile-hydrophobic ratio of organics which were determined by organic conceptional diagram developed by Fugita was investigated.
It was observed that the hydrophilic properties tended to promote the activated carbon adsorbability and the hydrohile properties tended to promote the biodegradability with some exceptions. Some informations on treatability were obtained when the organics were classified on the hydrophile-hydrophobic properties which corresponded to the ratio of biodegradability to activated carbon adsorbability.

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Optimal allocation scheme of feeding wastewater into aeration vessels is studied. So far a very few works have quantitatively evaluated advantages (or disadvantages) of modifing feeding scheme of inlet wastewater despite the long and practical use of step aeration processes. The evaluation herein is made based on the two criteria, i.e., “time average treatment efficiency” and “stability of time variation of effluent quality”.
The result implies the followings :
(1) The conventional way of step feeding is not always advantageous in terms of the above two criteria.
(2) The performance of aeration vessels is improved only by the optimized feeding scheme. Needed now is to accumulate practical data to ascertain the present numerical analysis.

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Marine planktons being dominant in the Inland Sea of Seto, Gymnodinium sp. (Gym. sp.), Hemieutreptia antiqua HADA (H. antiqua), Chiamydomonas sp. (Chl. sp.), Skeletonema sp. (Ske. sp.) and Nayicula sp. (Nav. sp.) were studied to examine the nutritional requirements for the growth and an applicability of eutrophication assessment of the sea water from the Hiroshima Bay.
Nitrogen source as nitrate and phosphorus source as phosphate were essential nutrients for the growth, however, some overplus uptake of phosphorus at the beginning of the growth could further support the growth on phosphorus free media. Cell yields based on nitrogen, ×10⁵cells/μg N and phosphorus, ×10⁵ cells/μg P were measured to be 0.4 and 3.1 for Gym. sp., 3.0 and 28.0 for Chl. sp., and 7.0 and 28.6 for Ske. sp., respectively. The mixture of vitamin B₁ and B₁₂, and biotin enhanced the growths of Gym. sp., H. antiqua and Nav. sp. whereas Chl. sp. and Ske. sp. did not require the vitamins for their growths. Vitamin B₁₂ was an essential growth factor for the growths of Gym. sp. and Nav. sp.
The growth activities of Chl. sp. and Ske. sp. when they were grown on the media based on sea water from St. 1 to 3 either with or without spiking N or P or N and P suggested that nitrogen concentration in the sea water might be a growth limiting nutrient for the planktons rather than phosphorus. Relatively low concentrations of nitrogen and phosphorus might be classified the sea water of the Hiroshima Bay as a mesotrophy. The increases of growth activities of Gym. sp., H, antiqua and Nav. sp. when vitamin B₁₂ was spiked in the samples from St. 2 suggested that vitamin B₁₂ or its related substance might be a growth limiting factor for vitamin B₁₂-requiring plankton in St. 2.

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In the road pavement works at Yame in Fukuoka prefecture in 1975, the well water along the work area were suddenly contaminated by Mn.
Since there were no obvious sources of Mn, the origin of Mn and the cause of Mn elution were studied with respect to the interaction between the soil and the road construction materials.
It was found that Mn was eluted neither from the road construction materials nor from the soil alone. However, Mn was eluted out from the soil when it was treated with the water contacted with the slag. The following results were found in relation to the mechanism of Mn elution.
(1) When the slag was extracted with water a considerable amounts of Ca²⁺, Na⁺, K⁺ and S^2-_ were eluted out.
(2) A model “slag-water” prepared by dissolving an appropriate salt of Ca²⁺, Mg²⁺, Na⁺ or S^2- in distilled water showed a remarkable ability to elute Mn from the soil.
(3) The slag used in the pavement works was the “fresh” one that was obtained just after production.
The “fresh” slag gave much more amounts of those ions mentioned in (1) than the “aged” slag. It was concluded that the Mn elution in the road pavement works involved the following sequence of events : elution of Ca²⁺, Na⁺, K⁺ and S^2- from the slag, reduction of Mn³⁺ to Mn²⁺ in the soil, and the elution of Mn²⁺ into solution through ion-exchange with Ca²⁺, Na⁺ and K⁺.

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Fluorescence spectra of 4 river waters at 36 points in Kanagawa prefecture were measured to investigate the possibility as a predictor of COD, MBAS, nitrate and phosphorous compounds. The river waters showed a highly significant correlation statistically between fluorescence and COD. Correlation of fluorescence with MBAS, T-N, NH₃-N, Org-N, T-P and PO₄-P were also found to be very good. The results showed that fluorescence could be used as a predictor of COD and the other 6 pollutants.
From the reason that high correlation existed between fluorescence and pollutants discharged by human activity, origin of fluorescence was studied focussing on fluorescent whitening agents (FWAs) used in detergents, textiles and papers. Two types of FWAs, diaminostilbene disulphonic acid type and bis (sulphostyryl) diphenyl type, could be identified in river waters by using the extraction method developed in this study and thin layer chromatography. The experimental results suggested that fluorescence of FWAs comprised 5070% of that observed in river waters.

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The synthetic investigations of mercury contamination in the Agano River were carried out for two years from 1976 to 1977 spending over 40 million yen. Since, higher concentration of mercury than the temporary standard of elimination was detected in a bottom sediment near the place of the discharge of “Kanose Denko Corp.” factory on the periodical investigations of mercury in August, 1975.
From investigations, in general, distribution of mercury concentration in bottom sediment of Agano River seemed to be the level of other noncontaminated rivers. High concentrations of mercury were found out from soil and the industrial waste deposit near the factory, but there was no worry for influences of mercury on the river, because the mercury in soil was confined in soil, solubility seemed very small, and there was little amount of methyl-mercury.
The concentrations of mercury in the industrial waste water and the water of the Agano River were not beyond the effluent standard or the environmental quality standard. But locally, from the place of the discharge to 150m downstream on right hand shore, there were some effects of mercury contents on some biological groups by the discharge of the factory. However, after the settling tank newly established, the effects of mercury in the dischage on the organisms were becoming small and the water environment concentration of mercury was near the value of natural fluctuations.
In general, influences of artificial contamination of mercury seemed to be almost cancelled in the Agano River.

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