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以我国北方某市政再生水厂的出水为研究对象,采用失重法和电化学测试法研究了该再生水对铸铁材料的腐蚀特性,同时考察了初始pH值和含盐量对腐蚀的影响效应。失重法和电化学测试结果均表明,该再生水对铸铁材料的腐蚀速率随时间的延长而逐渐降低,并最终趋于稳定。用失重法比较再生水和自来水对铸铁的腐蚀情况,发现在初期再生水的腐蚀速率大于自来水,但随着时间的延长,二者腐蚀速率的差异逐渐缩小。电化学测试结果表明,铸铁在再生水中能形成抑制腐蚀的保护层。当pH值为6.5～8.2时,铸铁在再生水中的腐蚀速率随pH值的升高而降低。经纯水稀释后的再生水对铸铁的腐蚀速率有增加的趋势,表明仅以含盐量和Larson指数等来评价再生水的腐蚀性是不可靠的。
Taking the effluent from a municipal wastewater treatment plant in the north of our country as the research object, the corrosion characteristics of the reclaimed water on cast iron were studied by weight loss method and electrochemical test, and the effects of initial pH value and salt content on corrosion were also studied. Both the weight loss method and the electrochemical test results show that the corrosion rate of the reclaimed water to the cast iron material gradually decreases with time and eventually tends to be stable. The corrosion of reclaimed water and tap water on cast iron was compared by weight loss method. It was found that the corrosion rate of reclaimed water was higher than that of tap water at initial stage, but the difference of corrosion rate gradually decreased with time. Electrochemical test results show that cast iron can form a protective coating that inhibits corrosion in reclaimed water. When the pH value is 6.5 ~ 8.2, the corrosion rate of cast iron in reclaimed water decreases with the increase of pH value. The corrosion rate of reclaimed water diluted with pure water tends to increase, indicating that it is unreliable to evaluate the reclaimed water’s corrosivity only with salt content and Larson index.