Mechanism of Biological Corrosion of Sewer Pipe and Its Control

本研究的目的是，（1）阐明微生物腐蚀的机理和（2）制定控制腐蚀的对策。1990年阐明了H_2S的产生与有机质（有机酸等）、硫酸盐浓度和硫酸盐还原菌的数量。1991年，我们研究了环境因素对污水管道腐蚀速率的影响。结果表明，H_2S浓度、含水量和温度是影响脱硫效果的重要因素。水线周围腐蚀严重。该部分的腐蚀速率范围为4至8 mm/年。产生的腐蚀材料取决于pH值。

Objectives of this research are, (l)to clarify the mechanism of microbial corrosion and(2)to develop the countermeasures in order to control the corrosion. Especially the focus was placed on the investigation from the aspect of microbiology.In 1990, it was clarified that there was the close relationship between H_2S production and some environmental factors such as organic matter(organic acids etc.), sulfate concentration, and the number of sulfate reducing bacteria. The H_2S was produced mostly from sediments in sewer pipes.In 1991, the effect of environmental factors on the corrosion rate were investigated. It was revealed that H_2S concentration, moisture contents and temperature are the important factors. The corrosion was serious at the portion around the water lebel. The corrosion rate of the portion ranged from 4 to 8 mm/year. The corroded materials produced depended on pH values.