供水管网中微生物对铸铁管材腐蚀的影响

Influence of Microorganisms in Water Distribution System on Cast Iron Pipe Corrosion

硫酸盐还原菌和铁细菌是供水系统中影响管材腐蚀的主要微生物,从供水管线中提取这两种微生物,通过对样片的腐蚀情况分析获得微生物的生长曲线及相应的腐蚀速率。结果发现,两种微生物的生长曲线都在第3天和第4天后趋于稳定,不同于二者共存时的结果。在35℃时,铁细菌数量增长最快。浸泡在微生物中样片的腐蚀速率明显大于浸泡在灭菌水中的腐蚀速率。硫酸盐还原菌对铸铁腐蚀的影响最大,两种微生物混合时,样片的腐蚀速率最小,说明当硫酸盐还原菌和铁细菌共存时,铸铁管材的腐蚀过程受到抑制。在不同介质中浸泡过的铸铁样片,其腐蚀电位也存在较大差异。

Sulfate reducing bacteria （SRB） and iron bacteria are the main microorganisms that af- fect the corrosion process in water distribution systems. Localized corrosion behavior of cast iron pipelines was investigated in the presence of SRB and iron bacteria isolated from water distribution systems. Cou- pon tests were conducted to acquire the corrosion rate and the growth curve of bacteria. Ecorr of SRB and iron bacteria differed from each other and the growth curve varied when they coexisted. The growth curve of bacteria inclined towards steady state after 3 or 4 days. The growth curve of iron bacteria was different from that of mixed bacteria. The quantity of iron bacteria increased the most quickly at 35 ~C. With the immersion in the bacteria, the corrosion rate increased obviously compared to that exposed to drinking water. SRB had greater impact on the corrosion process than iron bacteria. The sample within the mixture of bacteria presented the lowest corrosion rate, showing that cast iron pipe corrosion process was inhibited when SRB and iron bacteria coexisted. The corrosion potentials of cast iron coupons immersed in different media were quite different.