基于弱电场调控的生物活性炭降解溴酸盐技术

Ozone-BAC technology is widely used to treat drinking-water, but for source-water containing bromide, ozone oxidation gives rise to carcinogenic bromate. Therefore, in this study, the removal of bromate in water as the main goal, the weak electric fields of 2 Vcm-1 was used to change the permeability of cytomembrane. The promotion of intracellular enzymes transporting through the membrane, consequently improves the bromate biodegradation activity. Besides the thickness of biofilm increased by weak electric fields can regulate the concentration gradient of dissolved oxygen (DO), and thereby avoided the competitive degradation of bromate. The concentration of intracellular and extracellular nitrate reductase were measured, it was for studying the effect of membrane transport modes on the biochemical metabolism of bromate; Based on the determination of EPS thickness and components of proteins and polysaccharides, in addition the studies of DO concentration gradient in biofilm, the XDLVO sorption theory in presence of weak electric fields was established; Last, the technique of weak electric fields mediated BAC was operated in bromate removal and the manipulating conditions was optimized. The use of electric fields to help the release of intracellular enzymes, providing a low DO micro-environment for avoiding competitive degradation of bromate, it is ultimately to enhance the BAC biodegradability of bromate in source water.

臭氧-生物活性炭技术广泛应用于处理饮用水水质，但是对于含溴离子的水源水来说，臭氧氧化会导致溴酸盐致癌物质的产生。为此，本研究以消减水中溴酸盐为主要目标，利用2Vcm-1的弱电场改变膜通透性，促进胞内酶在细胞膜上的运输，提高溴酸盐的生物降解活性；同时增加生物膜厚度，促进膜上溶解氧的浓度梯度形成，避免溶解氧对溴酸盐降解竞争。通过研究胞内和胞外硝酸盐还原酶的浓度，探讨细胞膜运输方式的改变对溴酸盐生化代谢的影响；测定生物膜EPS厚度以及其中蛋白质和多糖组分，研究生物膜厚度引起的溶解氧浓度梯度，建立电场调控的XDLVO生物膜吸附理论模型；最后，弱电场作用的生物膜活性炭操作技术应用在含溴酸盐水源水中，优化运行条件。总之，利用电场帮助胞内酶的释放，提供低溶解氧的微环境，提高生物活性炭对水源水中溴酸盐的生物降解能力。

水体中广泛分布的痕量污染问题已成为当前一大热点,而传统手段对其去除效果较差,因此针对这类污染物的新型去除技术已受到越来越多的关注。弱电场控制的生物活性炭处理技术是将活性炭吸附和生物降解，耦合到电场调控的杂交方法总称，包括利用电场刺激非极性、离子型污染物定向扩散进入活性炭内部被吸附，以及促进生物降解酶向胞外的跨膜运输。研究以电场引发电渗流 (EOF)为目标，数值解析基质表面电荷诱导产生的孔隙流EOF速度。基于了解部分离子型污染物会被电极直接还原的基础上，提出EOF能够促进污染物深入活性炭内部孔隙而被捕获的调控措施。通过比较施加电场前后非极性污染物被吸附和解吸的速率和程度，确定EOF速度与污染物吸附平衡所需吉布斯自由能() 之间的相关关系。此外还研究了电场调控下微生物细胞膜发生β-氧化，促进胞内降解酶释放到胞外的机制。由此，提出弱电场控制的生物活性炭处理技术可以作为一种动力学控制疏水性污染物与吸附剂相互作用的方法，保障孔隙吸附的污染物及时被胞外酶快速降解，达到吸附剂再生而深度处理的最终目标。