污水环境下硫氧化细菌形成的生物被膜及其对砂浆微观性能的影响

Biofilm Formed by Sulfur-Oxidizing Bacteria in Sewage and its Effect on Micro-Properties of Mortar

使用电化学阻抗谱、扫描电子显微镜、热分析仪、X射线衍射仪等测试手段研究污水环境下硫氧化细菌形成的生物被膜基本特征及其对砂浆微观性能的影响。结果表明:30 d砂浆表面已经附着成熟的生物被膜,从宏观研究发现生物被膜是透明且含有白色物质的黏稠物,从微观研究发现生物被膜是由棒状硫氧化细菌包裹着胞外聚合物(EPS)形成的一种膜结构;90d生物被膜厚度、蛋白质含量光密度(OD)值、微生物数量OD值分别比30d生物被膜厚度、蛋白质OD值、微生物数量OD值低1.59 mm、0.086、1.614,表明90 d砂浆表面生物被膜已经处于解体阶段。随着龄期的增加,砂浆试样电化学阻抗谱前半部分半圆半径逐渐变大且后半部分直线倾斜角度变大,砂浆内部逐渐产生板状的产物石膏,其内部孔隙逐渐被石膏填充。与30 d龄期相比,90 d试样石膏含量相对较多,而且90 d附着生物被膜试样内部石膏脱水含量比90 d未附着生物被膜试样内部石膏脱水含量多0.248%。硫氧化细菌形成的生物被膜对砂浆起到腐蚀加深的作用。

Biofilm and the microscopic properties of mortar were investigated by electrochemical impedance spectroscopy,scanning electron microscopy,thermal analysis and X-ray diffraction.The results show that a mature biofilm can be formed on the surface of mortar at 30 d.In a macroscopic study,the biofilm is a transparent and viscous substance containing white matter.In a microscopic study,the biofilm is a film structure formed by rod-shaped sulfur-oxidizing bacteria wrapped with extracellular polymeric substances(EPS).The biofilm on the surface of 90 d mortar is in the disintegration stage.The thickness,protein optical density(OD)value and microorganism number OD value of the 30 d biofilm are 1.59 mm,0.086,and 1.614,respectively,which are higher than those of the 90 d biofilm.Based on the results of a microscopic study,the plate-like mineralized gypsum gradually occurs in mortar,the semicircular diameter of the first half of the electrochemical impedance spectrum gradually becomes larger and the inclination angle of the second half of the straight line becomes larger,and some pores in mortar fill with gypsum when the test age increases.Compared to the 30 d test age,the 90 d gypsum content is relatively larger,and the 90 d adhered biofilm dehydrated content of gypsum is 0.248%greater than the 90 d unattached biofilm dehydrated content of gypsum.This indicates that the biofilm formed by sulfur-oxidizing bacteria could have a corrosive deepening effect on mortar.