Yu Wenzheng, Brown Matthew, Graham Nigel J D
Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
Sci Rep. 2016 Jul 20;6:30144. doi: 10.1038/srep30144.
Pre-treatment is normally required to reduce or control the fouling of ultrafiltration (UF) membranes in drinking water treatment process. Current pre-treatment methods, such as coagulation, are only partially effective to prevent long-term fouling. Since biological activities are a major contributor to accumulated fouling, the application of an oxidation/disinfection step can be an effective complement to coagulation. In this study, a novel pre-treatment method has been evaluated at laboratory scale consisting of the addition of low dose ozone into the UF membrane tank after coagulation and the use of a hollow-fibre membrane coated with/without MnO2 nanoparticles over a test period of 70 days. The results showed that there was minimal fouling of the MnO2 coated membrane (0.5 kPa for 70 days), while the uncoated membrane experienced both reversible and irreversible fouling. The difference was attributed to the greatly reduced presence of bacteria and organic matter because of the catalytic decomposition of ozone to hydroxyl radicals and increase of the hydrophilicity of the membrane surface. In particular, the MnO2 coated membrane had a much thinner cake layer, with significantly less polysaccharides and proteins, and much less accumulated organic matter within the membrane pores.
在饮用水处理过程中，通常需要进行预处理以减少或控制超滤（UF）膜的污染。目前的预处理方法，如混凝，在防止长期污染方面仅部分有效。由于生物活性是累积污染的主要因素，氧化/消毒步骤的应用可以成为混凝的有效补充。在本研究中，在实验室规模下评估了一种新型预处理方法，即在混凝后向超滤膜池中添加低剂量臭氧，并在70天的测试期内使用涂覆/未涂覆MnO₂纳米颗粒的中空纤维膜。结果表明，涂覆MnO₂的膜污染极小（70天内为0.5kPa），而未涂覆的膜经历了可逆和不可逆污染。这种差异归因于臭氧催化分解为羟基自由基导致细菌和有机物的存在大大减少，以及膜表面亲水性的增加。特别是，涂覆MnO₂的膜具有更薄的滤饼层，多糖和蛋白质明显更少，膜孔内累积的有机物也更少。
