貯溜屎尿中における蛔虫卵の死滅に及ぼす温度の影響
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概要
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As part of fundamental studies on the use of a special tank for converting.organic matter in night soil into more suitable form before night soil is disposed of by being used as manure, the author performed studies on the influence of temperature on the survival of Ascaris eggs in night soil in the process of digestion. The survival rate of Ascaris eggs in the tank would serve as an index for functional activities of the tank. Ascaris eggs were exposed to differing temperature, 45℃, 40℃, 37℃, 30℃, and 25℃, as well as to a normal room temperature, in tanks experimentally simulated, and their survival rates were investigated. On the other hand, the behavior of Ascaris eggs in some tanks already in practical operation was subjected to studies, and the results were correlated with those of experimental studies. (1) It was shown that higher the temperature to which eggs were exposed, the lower was the survival rate of them. (2) All the eggs exposed to 45℃ died in 8 hours. (3) The survival rate of the eggs exposed to 40℃ was reduced to less then 65 per cent in 2 hours. They all died in 4 to 5 days. (4) It was presumed that the eggs exposed to 37℃ would dieun 7 to 10 days, depending on circumstances. (5) It seemed that it would take 45 to 50 days for all of eggs to die if they were exposed to 30℃. (6) When eggs were exposed to 25℃ for 75 days, only 1 per cent of them survived. It would take 80 days for all of them to die in this condition. (7) When eggs in a simulated experimental tank were kept at a room temperature of 18.4℃, an average temperature for the period from February to October, 11 per cent of them survived in 190 days. They all died in 200 days. (8) Examinations of Ascaris eggs in the tank at Muroran, Hokkaido where night soil is stored for 15 days and heated at 35℃ showed that 76 per cent of the eggs found in raw night soil were live ones, while the rates of survival in the sludge deposited in the bottom and in the supernatant were 15 per cent and 15.5 per cent, respectively. (9) In the digestion tank at Sunamachi, Tokyo where night soil is heated at 30℃ and stored for 30 days, 88.1 per cent of Ascaris eggs found in raw night soil were live ones, while 35 per cent and 13.5 per cent of the eggs found in the sludge sedimented in the bottom and in the supernatant, respectively, were live ones. There were no live eggs in the dried sludge. (10) In the tank at Shuzenji, Shizuoka where night soil is stored for digestion without being heated, the survival rates of Ascaris eggs were 73.7 per cent in raw night soil, 47.5 per cent in the sludge and 17.8 par cent in the supernatant. Twenty-two per cent of the eggs found in the dried sludge were live ones. (11) In view of the results of present studies, it would seem that, while the temperature lower than 30℃.would have no effect on expediting digestion of night soil, extermination of Ascaris eggs would result if night soil were stored for 15 days and heated at 37℃.
- 千葉大学の論文
- 1958-11-28