Wang Xiao-Mao, Li Xiao-Yan
Environmental Engineering Research Centre, Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Water Res. 2008 Feb;42(4-5):855-62. doi: 10.1016/j.watres.2007.08.031. Epub 2007 Sep 7.
A laboratory-scale submerged membrane bioreactor (SMBR) with a hollow-fibre membrane module was used to investigate membrane fouling under various operational conditions. The results showed that the sludge supernatant inside the SMBR had a consistently higher organic content than the MBR effluent. Detailed analysis revealed a pool of organic substances, classified as biopolymer clusters (BPC), in the SMBR system that were larger in size than the soluble microbial products (SMP). The BPC content in the MBR sludge mixture ranged from 0.7 to 18.8 mg/L in terms of the total organic carbon (TOC), with an average of 5.6+/-3.5mg/L, which was about twice the SMP concentration in the suspension. Under a fluorescent microscope and using DAPI staining, the BPC in the sludge supernatant after centrifugation were found to be particulate organic substances that were independent of the sludge flocs and had a size distribution up to 50 microm. The findings of the experiment suggest that BPC are an important foulant and have a profound effect on membrane fouling. The fouling rate in the reactor, as indicated by the increase in trans-membrane pressure (TMP), correlates to a certain extent with the BPC concentration in the sludge suspension under various conditions. It is argued that BPC are a special form of organic substances that are formed by the adsorption and affinity clustering of mainly SMP within the sludge layer deposited on the membrane surface. The BPC can be detached with the sludge from the membrane and returned to the suspension. The accumulation of BPC in the SMBR sludge mixture would facilitate the formation of a sludge fouling layer on the membrane surface, thus causing a serious fouling problem.
使用带有中空纤维膜组件的实验室规模的浸没式膜生物反应器（SMBR）来研究各种运行条件下的膜污染情况。结果表明，SMBR内部的污泥上清液中的有机物含量始终高于MBR出水。详细分析表明，SMBR系统中存在一类被归类为生物聚合物聚集体（BPC）的有机物质，其尺寸大于可溶性微生物产物（SMP）。就总有机碳（TOC）而言，MBR污泥混合物中的BPC含量在0.7至18.8mg/L之间，平均为5.6±3.5mg/L，约为悬浮液中SMP浓度的两倍。在荧光显微镜下使用DAPI染色，发现离心后的污泥上清液中的BPC是独立于污泥絮体的颗粒状有机物质，尺寸分布可达50微米。实验结果表明，BPC是一种重要的污染物，对膜污染有深远影响。由跨膜压力（TMP）增加所表明的反应器中的污染速率在一定程度上与各种条件下污泥悬浮液中的BPC浓度相关。有人认为，BPC是一种特殊形式的有机物质，主要由沉积在膜表面的污泥层内的SMP吸附和亲和聚集形成。BPC可以与污泥一起从膜上脱离并返回悬浮液中。SMBR污泥混合物中BPC的积累将促进膜表面形成污泥污染层，从而导致严重的污染问题。
