混凝-微滤膜组合净水工艺中膜过滤特性及其影响因素

采用混凝-微滤膜组合工艺处理微污染原水,间歇抽吸的运行方式连续运行,考察了膜组件的抽吸时间,抽/停时间比和曝气量对膜过滤性能的影响.采用膜通透性J/p作为膜过滤性能的评价指标.结果表明,在各操作条件下,膜通透性J/p由于膜污染的发生均先快速降低,随后随时间缓慢下降.但J/p的初期下降速度和缓慢下降阶段的相对稳定值因操作条件的不同而不同.抽吸时间对膜通透性影响较大,其次为抽/停时间比.在一定的条件下,抽吸时间缩短1/2,产水率可提高2倍;抽/停时间比缩短,产水率可提高50%.当抽吸时间和抽/停时间比分别为15min和3.8时,J/p值较高.曝气量在一定范围内的增加有利于提高膜通透性.本试验中,曝气量由2m³/h增加至4m³/h时,膜通透性可提高约15%,但当曝气量增加到6m3/h时,膜通透性并无显著改善.膜面污染物分析表明,在本研究使用的原水条件下,Si和Ca是主要的无机污染元素.

Membrane Filtration Characteristics and Its Influencing Factors in Coa-gulation-Microfiltration Combination Process for Water Purification

A coagulation microfiltration combination process was used to treat micro polluted raw water in the intermittent operation mode. The effect of the operational parameters such as filtration time and aeration intensity, on the membrane filtration characteristics was investigated. An indicator J/p, defined as flux per unit pressure, was employed. At all the experimental conditions, J/p always fell down fast at first owing to membrane fouling, and then decreased slowly. But the initial decreasing rate and relative stable value of J/p in the latter period depended on the different operational parameters.J/p was greatly influenced by the filtration time, then the ratio of the filtration time to the ceasing time. Under the condition the filtration time was shortened by 1/2, the flux will increase by two times; when the ratio of filtration time/ceasing time was shortened, the flux was increased by only 50%. Higher J/p value could be achieved at the filtration time of 15 min and the ratio of filtration time/ceasing time of 3.8. Increased aeration intensity could enhance J/p to some extent. In the experiments, when the aeration intensity was increased from 2 to 4m³/h, the membrane permeability was increased by about 15%; and the membrane permeability would not increased if the aeration intensity was continuously increased to 6m³/h. Primary inorganic elements on the membrane surface at the present experimental condition were found to be Si and Ca from the element analysis.