Wetsus Centre of Excellence for Sustainable Water Technology, P.O. Box 1113, 8900 CC Leeuwarden, The Netherlands; BIOMATH, Department of Mathematical Modelling, Statistics and Bioinformatics, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
BIOMATH, Department of Mathematical Modelling, Statistics and Bioinformatics, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium; modelEAU, Département de génie civil et de génie des eaux, Université Laval, 1065 Avenue de la Médecine, Québec QC G1V 0A6, Canada.
Water Res. 2015 Jun 1;76:99-109. doi: 10.1016/j.watres.2015.02.057. Epub 2015 Mar 5.
While most membrane bioreactor (MBR) research focuses on improving membrane filtration through air scour, backwashing and chemical cleaning to physically counteract fouling, relatively few studies have dealt with fouling prevention, e.g. minimizing the impact of operational settings that negatively impact sludge filterability. To evaluate the importance of those settings, the effects of bioreactor aeration intensity variations on membrane fouling have been studied in a lab-scale MBR setup while simultaneously monitoring a unique set of key sludge parameters. In particular, this paper focuses on the impact of shear dynamics resulting from fine air bubbles on the activated sludge quality and flocculation state, impacting membrane fouling. When augmenting the fine bubble aeration intensity both the total and irreversible fouling rate increased. Major indications for sludge filterability deterioration were found to be a shift in the particle size distribution (PSD) in the 3-300 μm range towards smaller sludge flocs, and increasing concentrations of submicron particles (10-1000 nm), soluble microbial products and biopolymers. When lowering the aeration intensity, both the sludge characteristics and fouling either went back to background values or stabilized, respectively indicating a temporary or more permanent effect, with or without time delay. The shift in PSD to smaller flocs and fragments likely increased the total fouling through the formation of a less permeable cake layer, while high concentrations of submicron particles were likely causing increased irreversible fouling through pore blocking. The insights from the performed fouling experiments can be used to optimize system operation with respect to influent dynamics.
虽然大多数膜生物反应器 (MBR) 研究都侧重于通过空气冲洗、反冲洗和化学清洗来改善膜过滤，以物理方式抵抗污染，但很少有研究涉及防污，例如尽量减少对污泥过滤性能产生负面影响的操作设置的影响。为了评估这些设置的重要性，在实验室规模的 MBR 装置中研究了生物反应器曝气强度变化对膜污染的影响，同时同时监测一组独特的关键污泥参数。特别是，本文重点研究了由于细小气泡产生的剪切动力学对活性污泥质量和絮凝状态的影响，从而影响膜污染。当增加细小气泡曝气强度时，总污染率和不可逆污染率均增加。污泥过滤性能恶化的主要迹象是 3-300 μm 范围内的颗粒尺寸分布 (PSD) 向更小的污泥絮体转移，以及亚微米颗粒（10-1000nm）、可溶性微生物产物和生物聚合物的浓度增加。当降低曝气强度时，污泥特性和污染分别恢复到背景值或稳定，这分别表明存在暂时或更永久的影响，是否存在时间延迟。PSD 向更小的絮体和碎片的转移可能通过形成更不可渗透的滤饼层而增加总污染，而亚微米颗粒的高浓度可能通过孔阻塞导致不可逆污染增加。从进行的污染实验中获得的见解可用于根据进水动力学优化系统运行。
