环境扫描电镜对废水生物样品形态结构的表征研究

采用环境扫描电镜(ESEM)分析颗粒污泥和悬浮填料生物膜的微生物群落形态,并与扫描电镜(SEM)观察结果进行比较.结果表明,ESEM观察悬浮填料生物膜的适宜条件为样品台温度5℃,样品室汽压5.91×102Pa,相对湿度75%,加速电压15.00kV.观察颗粒污泥样品的适宜条件为样品台温度0℃,样品室汽压7.00×102Pa,相对湿度100%,加速电压10.00kV.表面存在的水滴凝聚和含水量高、结构脆弱的样品易因气压和入射电子束轰击收缩变形,是影响ESEM观察样品真实面貌的主要因素.悬浮填料生物膜的ESEM观察说明,相较于SEM,未经任何处理的载体生物膜样品在合适的ESEM条件下可得到的高放大倍数的清晰照片,能更真实的表征生物膜的微生物群落结构.含水量高、结构脆弱,承受能力差的颗粒污泥样品,则需要通过锇酸或者戊二醛等固定剂进行化学固定,降低ESEM的加速电压,并且尽量缩短观察时间,避免因气压和高速入射电子束的轰击而收缩变形,获得其原始形貌照片.

Application of ESEM in the visualization of microbial community of granule sludge and suspended carrier biofilm

The structure of the microbial community of suspended carder biofilms and granule sludge was visualized by ESEM, and the images were compared with SEM. The optimal condition for suspended carder biofilms was temperature of 5℃, chamber pressure of 5.91×10~2 Pa, the relative humidity of 75%, accelerating voltage of 15.00kV, and that for granule sludge was temperature of 0℃, chamber pressure of 7.00×10~2 Pa, the relative humidity of 100%, accelerating voltage of 10.00kV. The partial coverage of the samples by free water and the potential damage to the fragile nature of the wet samples with the electronbeam and air pressure were the main technical constraints to obtain good quality images. ESEM permits the the observation of wet samples without complex sample preparation or conductive coating, which provide a novel tool for characterizing granule sludge and suspended carder biofilm.