直流电场对凝胶型膜污染层的作用

Impact from direct electric field on gel-type membrane fouling

膜污染制约着膜技术的发展与应用,形成膜污染的物质多带有负电荷,理论上电场可有效控制膜污染形成和发展.本研究采用富含形成凝胶型污染物质的膜生物反应器上清液为过滤原液,考察直流电场对形成中和形成后的污染层的作用.研究发现,对形成中的膜污染层,膜通量随电压强度的升高而升高;而对已形成的膜污染层,则需要合适的电压和通电时间以提高其膜通量.对膜污染层的结构和成分的分析表明,电场可使膜表面凝胶层的交联度降低、孔隙率增大,从而有效降低凝胶类污染;但高电压(如15V)下水的电解会导致已形成的膜污染层沉积大量颗粒沉淀而使得膜通量快速下降.

Development and application of membrane technologies were restricted by fouling.Foulants were majorly negatively charged,thus,in theory,electric field could effectively suppress the formation and evolution of fouling.In this study,membrane-bioreactor supernatant,which contained great amount of foulants to form gel-type fouling during filtration,were adopted as the feed water,and the effect of a direct electric field on both developing and developed fouling layer were investigated respectively.It was observed that the flux during the fouling layer formation increased with the increment of voltage,while specific voltage and time could increase the flux of a fouled membrane.The analysis of the structure and component of the fouling layer illustrated that gel-type fouling layer would be loosen thereby the porosity were increased.But large number of precipitates were observed on the fouled membrane surface due to electrolysis of water under high voltage（15 V）,which led to an advanced reduction of flux.