Laboratory-scale sequencing batch reactor (SBR) activated sludge process was fed with synthetic wastewater to clarify the possibility on simultaneous removal of nitrogen, phosphorus, and organic substances by modifying operational schedule. Anoxic and/or anaerobic reactions in addition to aerobic reaction were introduced into a cycle of batch operation.
The following conclusions can be made from this study :
1) Simultaneous removal of nitrogen, phosphorus and organic substances was shown to be possible by the modified operation of SBR in which an anoxic/anaerobic stage was introduced during the fill period.
2) Oxidized nitrogen and activated sludge remained in the reactor at the end of the former cycle was removed by denitrification during the fill. Phosphorus was removed by the anaerobic release from the sludge during the fill followed by the luxury uptake by aeration.
3) Both extension and reduction of the first anoxic/anaerobic stage damaged plant performance, thus an optimum length of time for these reactions must be chosen for successful operations. The best length of this stage coincided with that of the fill within the range of this study.
4) The second anoxic/anaerobic and aerobic stage was not always necessary for successful nutrient removal. However, the introduction of these stages caused no detrimental effects on plant performance.

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An addition method of hydoxylammonium chloride in wastewater containing mercury was examined experimentally as a new tertiary treatment to remove mercury by adsorption operation with regenerable chelate resins prepared for heavy metals. It was found that the amount of mercury adsorbed by the resins and the adsorption rate were increased by addition of 0.05-0.1w·v^-1% of hydroxylammonium chloride in the wastewater and by adjustment of pH between 3.0-4.0. By the batchwise experiment in which initial concentration of mercury was 1.0mg·1^-1, an addition ratio of hydroxylammonium chloride was 0.1w·v^-1%, adjusted pH was 4.0 and weight of resins was 1.0g, the concentration of mercury observed at equilibrium was 0.03mg·1^-1 but the other side the concentration of mercury without hydroxylammonium chloride was 0.31mg·1^-1. And the time to reach at the equilibrium was one third the time obtained without hydroxylammonium chloride. Larger amount of adsorption and higher adsorption rate were also observed by columnwise experiment.
It was more better to use two types of resins equivalently which have calcium-and hydrogen-form respectively. Active carbon was the most profitable as an adsorbent for the post-treatment of hydroxylammonium chloride and the adsorption ratio was 1.1g·g-carbon^-1.

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In recent years, brackish Lake Nakanoumi which is being converted into a fresh-water lake by reclaming is rapidly eutrophicated, and its waters are heavily polluted.
This study was performed special attention paid on the Yonago Embayment which is the most heavily polluted area in the Lake Nakanoumi waters, and the primary production was measured by the in situ method.
The environmental factors controlling the primary production were sought for by multiple regression analysis using the measured data.
For a water depth of 0.5m, the three variables, i, e., grobal solar radiation, chlorophyll-a and water temperature, were found to fit into the multiple regression equation, and a high multiple correlation coefficient (r=0.921) was obtained.
The total amount of the primary net production in 1982 in the Yonago Embayment area was also estimated.

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