反渗透(RO)系统已越来越多地用于循环冷却水(CCW)回收。增塑剂,可以在塑料制造业中溶解到CCW系统中,不能通过RO系统之前的预处理完全去除,可能导致严重的膜生物污染。在痕量增塑剂的存在下,破译RO膜生物污染的特征和机理对于开发有效的污染控制策略至关重要。在这里,我们证明,暴露于低浓度(1-10μg/L)的三种典型的增塑剂(邻苯二甲酸二丁酯(DBP),在预处理的真实CCW中检测到的磷酸三丁酯(TBP)和2,2,4-三甲基戊烷-1,3-二醇(TMPD))促进了大肠杆菌生物膜的形成。DBP,TBP和TMPD在5或10μg/L时显示出最高的刺激,生物量增加55.7±8.2%,分别为35.9±9.5%和32.2±14.7%,相对于未暴露的控件。因此,细菌暴露于微量增塑剂后显示出增强的三磷酸腺苷(ATP)活性,刺激细胞外聚合物(EPS)的排泄和抑制细胞内活性氧(ROS)的诱导,由相关基因的上调引起。长期研究进一步表明,在聚丙烯工厂中,经过预处理的真实CCW流动的RO膜表现出比暴露对照更严重的生物污染行为。而DBP和TBP部分对细菌增殖的刺激作用起关键作用。总的来说,我们证明,RO膜暴露于预处理的CCW中的微量增塑剂可以上调分子过程和生理反应,加速膜生物污染,这对基于膜的CCW处理系统中的生物污染控制策略具有重要意义。
Reverse osmosis (RO) system has been increasingly applied for circulating cooling water (CCW) reclamation. Plasticizers, which may be dissolved into CCW system in plastic manufacturing industry, cannot be completely removed by the pretreatment prior to RO system, possibly leading to severe membrane
biofouling. Deciphering the characteristics and mechanisms of RO membrane
biofouling in the presence of trace plasticizers are of paramount importance to the development of effective fouling control strategies. Herein, we demonstrate that exposure to a low concentration (1 - 10 μg/L) of three typical plasticizers (Dibutyl phthalate (DBP), Tributyl phosphate (TBP) and 2,2,4-Trimethylpentane-1,3-diol (TMPD)) detected in pretreated real CCW promoted Escherichia coli biofilm formation. DBP, TBP and TMPD showed the highest stimulation at 5 or 10 μg/L with biomass increasing by 55.7 ± 8.2 %, 35.9 ± 9.5 % and 32.2 ± 14.7 % respectively, relative to the unexposed control. Accordingly, the bacteria upon exposure to trace plasticizers showed enhanced adenosine triphosphate (ATP) activity, stimulated extracellular polymeric substances (EPS) excretion and suppressed intracellular reactive oxygen species (ROS) induction, causing by upregulation of related genes. Long-term study further showed that the RO membranes flowing by the pretreated real CCW in a polypropylene plant exhibited a severer
biofouling behavior than exposed control, and DBP and TBP parts played a key role in stimulation effects on bacterial proliferation. Overall, we demonstrate that RO membrane exposure to trace plasticizers in pretreated CCW can upregulate molecular processes and physiologic responses that accelerate membrane
biofouling, which provides important implications for
biofouling control strategies in membrane-based CCW treatment systems.