In shallow rivers that are enriched with nutrients, considerable amount of periphytons grow on the surface of stone and other material in river bed. This periphytons contribute to the increase in organic matters, because they slough continuously to the river water. For the precise estimation of water quality of above river condition, the rate of production of organic matters is to be determined.
In the study, the material balance of organics was determined by the experimental stream by means of the dissolved oxygen balance method proposed by H. T. Odum and the experimental results were compared with the calculated results.
According to this work the dissolved oxygen balance method was proved to be reasonable method for the estimation of the material balance of organics in the experimental stream.

View full abstract

The removal characteristics of several indicator microorganisms, in the treatment processes of municipal sewage, night soil and septic tank sludge were investigated.
As a result, the removal characteristics of bacteria in the processes of treatment varied according to the kinds of wastewaters and species of indicator microorganisms. In some cases, the heterotrophic bacteria multiplied in the treatment processes. In night soil treatment, coliforms and fecal coliformrs declined sharply in the wet oxidation process, while Clostridium perfringens and SPC bacteria remained almost in the same level. However, in sewage treatment and sludge treatment, the most effective process was found to be the activated sludge process and centrifugation process respectively, and nearly same efficiencies of reduction were observed in every species of indicator microorganisms.
Throughout the experiments, it was found that the chlorination process was not effective for the reduction of C. perfringens, while the activated sludge process could reduce all of the indicator microorganisms in the same efficiency.
Consequently, C. perfringens is recommended as the indicator for the evaluation of the treatment performance of microorganisms in physical and predative processes.

View full abstract

Mutagenicity test of humics after chlorination was carried out according to the liquid-cultivation method of Bacillus subtilis rec-assay.
An increase in mutagenic activity was observed with the increase of Cl₂/TOC in the range of Cl₂/ TOC = 1 10.
The DEAE Sephadex A-25 anionic exchange chromatography was employed for the fractionation of humic water before and after chlorination to characterize the mutagenic compounds. Chlorinated humics were fractionated into the nonanionic fraction (Group 1), the weak anionic fraction (Group 2), and the strong anionic fraction retained in column (Group 3). It was found out that mutagenic compounds are hydrophobic compounds extractable by dichloromethane in non-anionic fraction (Group 1).

View full abstract

The statistical analysis used by the observed data is attempted in this paper to present the degree of influence on the groundwater for chemical grouting coagulants such as water glass type liquid chemicals. The water qualities are investigated at observation wells in the vicinity of sewerage construction. The modified data excepting the characteristics of circumference are reevaluated in new independent variables which are exchanged the observed water quality items depend on each others.
The modified data induced by principal component analysis are clearly classified into the contaminated, the non-contaminated and the intermediate water quality groups. The data on intermediate group are dispersed in the boundary zone placed between the two groups.
The relationship between the principal component and the observation variables will be explained as follows ; the first principal component represents the degree of pollution by coagulant constituents such as Na, SiO² and M-alkality, the second principal component total hardness and the third principal component pH. And it is shown in the groundwater qualities contaminated by the coagulants, the values on first and third principal components are increased in opposite the second principal components. During the short period when coagulants are injected into groundwater, Na, SiO², M-alkality and the total hardess increased concurrently to form the intermediate group. Only in analysis of the contaminated group, the principal component axis is rotated for clarification and the result is obtained where pH and RpH correspond to the second principal component and total hardness corresponds to the third principal component.

View full abstract