The CCE concentration, identification by capillary-column GC-MS, molecular mass distribution using gel permeation chromatography, and intraperitoneal injection tests to mice were carried out concerning to the organic compounds in a supplied water
(1) The components which taked part in the CCE were mainly hexane-insoluble neutral materials. Because the CCE concentration was about 0.02ppm, the supplied water examined was considered fairly clean.
(2) The organic compounds identified included organic halogenated agricultural chemicals (α-BHC, TCTP, oxadiazon), plastic compounds (DMP, DEP, DBP, DOP, TBP), and ordorous compounds (acetophenone, diacetylbenzene, trichloroanisole) from artifical pollution and fatty acids originating in nature.
(3) The basic and acidic materials and the hexane-insoluble neutral materials in the components of the CCE were distributed at molecular mass of 2100 or below with a median mass of 600 when compared to polystyrene. But the hexane-soluble neutral materials were distributed at molecular mass of 800 or below.
(4) The intraperitoneal injection tests showed that the hexane-insoluble neutral materials and the highest polarity hexane-soluble neutral compounds (fraction 7) in the components of the CCE, which was concentrated from 11.2 tons of the supplied water, killed mice 25g bodyweight within 48 hours. This result indicated the supplied water was fairly clean.

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Results of laboratory experiments on the behaviour of suspended solids (s), dissolved organic carbon (DOC) and dissolved solids (DS) during the freezing process of sewage sludge are presented. Several cylinders containing excess activated sludge were put in a freezer chamber maintained at a constant temperature -16.5°C. Each cylinder was taken out of the chamber one by one in sequence of freezing time. A cylinder taken out at the freezing halfway contained partially frozen part. The unfrozen part was separated from the frozen part by decantation, and the latter was thawed, and both parts were analyzed. Remarkable improvement of solid-liquid separation characteristics was observed after the sludge temperature fell under the freezing point of the sludge. This change was accompanied with the rapid increase of DOC and DS of frozen part due to the release of organic matter from the cell structure. The DOC concentration of the freeze-and-thawed sludge was about 250 mg·l^-1, which was only one twentieth as compared to the DOC increase with heat treatment for sludge conditioning.

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Simultaneous removal of BOD, nitrogen and phosphorus from synthetic wastewater by the sequencing batch reactor activated sludge process and effect of nitrogen-phosphorus ratio (N/P) on the process were investigated experimentally. Behavior of nutrients in a cycle of 24 hours was also observed in the cases that wastewater was fed instantaneously and for first 2 and 8 hours in the cycle and that anaerobic conditions were introduced into a various stage of the cycle.
BOD was removed remarkably regardless of the duration of feeding and anaerobic conditions. Nitrogen was removed well in the most cases as long as wastewater did not contain phosphorus in excess. In cases of instantaneous feeding of wastewater, release of phosphorus from sludge occurred under anaerobic conditions when they were kept in early stages of the cycle but not observed when kept in latter stage of the cycle. Furthermore, it was found that so-called “luxury uptake” of phosphorus occurred in treating the wastewater not containing nitrogen greatly in excess.
The most desirable operational scheme and N/P in the wastewater for simultaneous removal of nitrogen and phosphorus for 2 or 8 hours feeding were to set anaerobic duration for the first 2 or 4 hours respectively in a cycle of 24 hours and to set N/P from 5 to 7.

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[in Japanese]

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