Since September 1984 when a large amount of foam was first found in lake Chuzenji, we have measured the concentrations of carbohydrate and protein in lake waters. The foam was present from late summer to autumn. The carbohydrate concentration was relatively high, while the protein concentration was almost below 0.1 mg·l^-1. Therefore, carbohydrate seemed to be one of the main causes of the foam while protein did not. We have thus investigated the origin of carbohydrate in the lake.
Because the primary production in the lake was much lower than the carbohydrate concentration during the foam was observed, carbohydrate from phytoplankton cannot be the main source for the foam. The concentration of carbohydrate having molecular weight above 100, 000, which seemed to be leached from fallen leaves and aquatic macrophytes, increased in autumn.
These results suggest that carbohydrate in the lake mainly originates from fallen leaves and aquatic macrophytes. The foam which was observed in autumn seems to be due to an increase in the concentration of high molecular weight carbohydrate.

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The adsorption behaviour of phosphate and the removal of phosphate from the primary effluent by the scoria and weathered pumice were investigated. The amount of phosphate adsorbed was significantly influenced by the equilibrium time, the concentration of phosphate, the equilibrium pH and the presence of competitive anions. The phosphate adsorption were analyzed by applying Langmuir equation. In the batch experiments the retention of phosphate were 370 μmol P·g^-1 for the red-colored scoria and 270 μmol P·g^-1 for the weathered pumice, which indicated higher adsorption capacity than other mineral soils. From the column experiment it is proved that the percolation is one of the most important factors in the removal of phosphate from the primary effluent. The scoria and weathered pumice were profitable materials to remove phosphate from the primary effluent.

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The treatment performance for a kind of kitchen wastewater has been studied by using a small scale laboratory apparatus in order to develop a pressurized type wastewater treating equipment with a biological carrier.
The first experiment showed that pressurized treating process is superior to atmospheric one in terms of oxygen transfer capability. It also showed that the higher the volume of circulated water continuously contacting with oxygen content shortage water in the apparatus is, the higher oxygen transfer capability becomes. It further showed that agitator blades in air/water dispersion tank are effective for oxygen transfer. In the second experiment, an actual kitchen wastewater was tested and TOD was measured. It showed that a BOD removal rate is 88 percent under a BOD load of 4.6kg BOD·m^-3·d^-1. The relation between BOD₅ of the kitchen wastewater and the BOD removal rate shows an equation of the first degree, Y = 0.025X + 0.62 and a correlation coefficient of r =0.87. The figures of MLSS ans MLVSS are low in case of a low BOD load, and becomes high in accordance with BOD load increase. The figure of MLSS is 6, 100 mg·l^-1 of carrier. The treating capability is 1.7 kg BOD m^-3·d^-1 under the condition of wastewater with 30 mg BOD·l^-1.

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[in Japanese]

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