生物膜对给水铸铁管腐蚀结垢的影响

Effect of Biofilm on the Corrosion and Fouling of Cast Iron Pipe for Water Supply

采用XRD、XPS对给水铸铁管腐蚀结垢产物进行表征,结合水相中总铁浓度变化规律,研究了生物膜生长对给水铸铁管腐蚀结垢的影响.结果表明,0～7d时生物膜存在条件下水相中总铁浓度更高,而15～30d时无生物膜生长的对照组水相中总铁浓度更高.有生物膜生长时,锈垢的XRD图谱主峰为铁氧化物;无生物膜生长时,主峰为CaCO3,次峰为铁氧化物,表明生物膜的存在会影响锈垢中晶体的生长及组成.7d时有生物膜生长组锈垢中铁的质量分数更高,而15d和30d时对照组锈垢中铁的质量分数更高.有生物膜生长组锈垢中钙的质量分数始终低于对照组,可能是胞外多聚物吸附或微生物生长消耗钙离子所致.上述结果表明,生物膜发育7d时会促进铸铁管的腐蚀,而发育15～30d时会抑制铸铁管的腐蚀;存在生物膜生长会对铸铁管锈垢的形态和组成产生重要影响.生物膜对腐蚀的抑制作用为控制配水管网管道的腐蚀提供了一条新的途径.

The crystalline phase and the element composition in the scales on cast iron pipe for drinking water was identified with XRD and XPS respectively to investigate the effect of hiofilm existence on the corrosion and fouling of cast iron pipe. The total iron concentration in the water phase was measured simultaneously. The results showed that on 0 -7 d the total iron concentration was higher in the water phase of the group with biofilm growth, but on 15-30 d it was higher in the water phase of the control without biofilm growth. The major peak of XRD patterns for the scales with biofilm growth was characterized as Fe oxide, while for the scales in the control it was always characterized as CaCO3. As presented by XPS atomic ratio, the Ca atomic percentage in the scales with biofilm growth was lower than that in the scales in the control, which might be contributed to the Ca^2＋ absorption by extracellular polymeric substances or Ca^2＋ consumption by microorganism growth. In comparison with that in the scales in the control, the iron atomic percentage in the scales with biofilm growth was higher on 7 d, while lower after 7 d. It can be concluded that on 0 -7 d the existence of biofilm could promote the corrosion of cast iron pipe while inhibit corrosion after 7 d. The variance of major peak of XRD pattern and XPS atomic ratio indicated that biofilm had important effect on the configuration and composition of the scales of cast iron pipe. The corrosion inhibition of biofilm thus provided a new pathway to control the corrosion of metal pipes in drinking water distribution system.