Solvent extraction was performed to characterize adsorbed materials on activated carbon and to evaluate a effective method of regeneration of the carbon, which was used in night soil treatment process. The exhaused carbon was extracted by the Soxhlet apparatus with three kinds of organic solvents (i.e., ethanol, chloroform, hexane), and dry-weight, COD, UV and IR spectrum and HPLC were measured. The amount of each solvent extract increased as the following order ; hexane < < chloroform < ethanol. The ethanol extract almost consisted of acidic components and the hexane extracted only small amount of neutral compounds. It was assumed that the most components of the adsorbed materials on the carbon were acidic. Based on these results, regeneration of carbon was investigated in column exctraction experiments using NaOH and/or H₂SO₄ solution. 0.1N -NaOH solution extracted 14.5mgCOD/g-AC, which was about 8 times larger than O.1N -H₂SO₄ extract. In this case, the major part of extracts was desorbed by small amount of solvent (12.5ml/g-AC). Two-step extraction with 0.1N -NaOH and 0.1N -H₂SO₄ brought about 71.8% regeneration rate, which was measured by iodine sorption capacity. It was found that there was a linear relation between the absorbance at 240nm and extracted COD or regeneration rate.

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The sediment oxygen demand (SOD^t_T) can be assumed to be a 4-phase process as follows :
1. Oxidation of many unstable chemical substances (SOD^t_C);2. Biochemical reaction for rapid assimilation of organic nutrients into bacterial cell. From the experimental data, this phase consists of a two-stage reaction (SOD^t_i1, and SOD^t_i2);3. And a subsequent slow oxidation of biological cell material through endogenous respiration (SODte).
Each reaction given above can mathematically be expressed by a first-order kinetics. These reactions contain no fewer than ten unknown parameters : four ultimate oxygen demands, four rate-constants, and two time-lags, but these parameters are determined by the modification of Lee's graphical method.
The sediment used is taken from three sea areas, including a drain pipe near sewage works, an oyster farm, and shido Bay.
In all sediments the rate-constants of the chemical oxidation, the bacterial growth phase, and the endogenous respiration are 2.2 day^-1, 1.6 day^-1, and 0.10 day^-1, respectively. And a summary of other parameters is shown in Table 2.
The component curves of SOD^t_T can mathematically be determined by using these results, and the course of SOD^t_T is calculated by summing the four component curves.
Consequently, the calculated curve agrees well with the observed data.

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River pollution in a developing country who has already took off for industrialization was studied. The study site was Naktong River basin in Korea. Major factors for the pollution were analyzed and problems associated with monitoring were pointed out. The pollution in Naktong River basin was not spread over the wide range of the stream and only a tributary running through the vicinity of Daegu, Geumho River, was polluted seriously by the activity around the city. The pollution was largely dependent on flow rate of Geumho river ; i.e. serious pollution was noted only in the low water. Also, the pollution in the main stream was observed only in the downstream of the junction of Geumho R. into Naktong R. for a short range by the self purification. Monitoring of the water, especially for chemical analyses such as BOD and COD was unreliable compared to flow rate measurement. The necessity of the training for chemical analysis and increase in the number of monitoring was pointed out.

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