Li Wen-Jiang, Yu Li-Fang, Miao Rui, Ma Bai-Wen
School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Huan Jing Ke Xue. 2018 Mar 8;39(3):1248-1255. doi: 10.13227/j.hjkx.201706137.
In recent years, the integrated ultrafiltration (UF) membrane process has been widely used due to its high removal efficiency, slight membrane fouling, and small land use. However, a number of problems gradually occurred regarding the integrated UF process caused by the granular adsorbents used, such as powdered activated carbon, carbon nano-tube, nanoscale zerovalent iron, etc. Severe membrane surface damage was easily caused by these granular adsorbents after a long running time, and the cost of most adsorbents was very high. In this study, to effectively overcome these problems, cheap and loose aluminum hydrolyzed flocs were directly injected into the membrane tank in the presence of humic acid (HA), with the aim of investigating the removal efficiency of HA and the corresponding membrane behavior. The results showed that the removal efficiency of HA could be influenced by aeration mode, floc injection frequency, and floc dosage. Compared with intermittent aeration and one-time injection, a loose "protection membrane" layer was formed with continuous aeration and batch injections. Therefore, HA molecules were largely removed, leading to the dramatic alleviation of membrane fouling. The transmembrane pressure significantly increased to 74.8 kPa in the absence of flocs after running for 5 days, but that only increased by 6.3 kPa with continuous aeration and an injection frequency of once every 2 d (each addition consisted of 5.4 mmol·L flocs) after running for 8 days. The removal efficiency of HA was 73.3% (8 d), which was much higher than in the absence of flocs (5 d, 32.1%). Additionally, only a few HA molecules were adsorbed onto the membrane pores with the batch injections, and a loose cake layer was the main fouling mechanism. With higher dosages of flocs injected each time, the average membrane pore diameter was larger after washing. Based on this excellent performance, this floc-integrated UF membrane technology indeed shows large application potential in water treatment.
近年来，集成超滤（UF）膜工艺因其去除效率高、膜污染轻微且占地面积小而被广泛应用。然而，由于使用了颗粒状吸附剂，如粉末活性炭、碳纳米管、纳米零价铁等，集成超滤工艺逐渐出现了一些问题。这些颗粒状吸附剂在长时间运行后很容易造成严重的膜表面损伤，而且大多数吸附剂成本很高。在本研究中，为了有效克服这些问题，在腐殖酸（HA）存在的情况下，将廉价且松散的氢氧化铝絮体直接注入膜池，旨在研究HA的去除效率及相应的膜行为。结果表明，HA的去除效率会受到曝气方式、絮体注入频率和絮体投加量的影响。与间歇曝气和一次性注入相比，连续曝气和分批注入形成了一层松散的“保护膜”层。因此，HA分子被大量去除，从而显著减轻了膜污染。运行5天后，无絮体时跨膜压力显著增加至74.8 kPa，但连续曝气且注入频率为每2天一次（每次投加5.4 mmol·L絮体）运行8天后，跨膜压力仅增加了6.3 kPa。HA的去除效率为73.3%（8天），远高于无絮体时（5天，32.1%）。此外，分批注入时只有少数HA分子吸附在膜孔上，主要的污染机制是形成松散的滤饼层。每次注入的絮体剂量越高，清洗后平均膜孔径越大。基于这种优异的性能，这种絮体集成超滤膜技术在水处理中确实显示出巨大的应用潜力。
