Coagulation and adsorption are gradually adopted as pre-treatments to produce reclaimed potable water. However, previous researches on membrane fouling mechanisms were currently insufficient to minimize dual membrane fouling. This study aimed at investigating the effects of pre-coagulation and pre-adsorption on the removal performance and membrane fouling alleviation of dual membrane UF/NF process in treating secondary effluent from a wastewater treatment plant. The results indicated that both types of pretreatments conferred positive effects on organic membrane fouling removal of the UF process whereas diverse effects on NF process. Pre-coagulation could enhance the removal of nitrogen and phosphorus to contribute towards producing microbiologically-stable water. On the other hand, introduction of Al³⁺ reduced the removal efficiency of UF/NF systems on heavy metals. From the perspective of UF membrane fouling, two pretreatments employed could increase the flux of UF, but simultaneously aggravating irreversible membrane fouling. Hermia and Tansel models revealed an unstable cake filtration was caused by pre-coagulation and pre-adsorption. Both the models consistently demonstrated the rapid formation of cake filtration onto UF membrane surface. Interestingly, the powdered activated carbon (PAC) adsorption could significantly reduce cake layer fouling onto the surface of NF membrane, while pre-coagulation aggravated the NF fouling. These results are essential to developing robust, cost-effective and energy-efficient strategies based on membranes to produce reclaimed potable water.

逐渐采用混凝和吸附作为预处理来生产再生饮用水。但是，对膜污染机理的先前研究目前不足以使双膜污染最小化。这项研究旨在研究预凝结和预吸附对双膜超滤/纳滤工艺在处理污水处理厂二次废水中的去除性能和膜结垢缓解的影响。结果表明，两种预处理都对去除超滤过程的有机膜结垢产生了积极影响，而对纳滤过程则产生了多种影响。预凝结可以增强氮和磷的去除，从而有助于产生微生物稳定的水。另一方面，Al ^3+的引入降低了UF / NF系统对重金属的去除效率。从超滤膜结垢的角度来看，采用两种预处理可以增加超滤的通量，但同时加剧了不可逆膜的结垢。Hermia和Tansel模型显示，不稳定的滤饼过滤是由预凝结和预吸附引起的。两种模型都一致地证明了滤饼在超滤膜表面的快速形成。有趣的是，粉状活性炭（PAC）的吸附可以显着减少NF膜表面上的滤饼层结垢，而预凝结会加剧NF结垢。这些结果对于开发基于膜的健壮，具有成本效益和能源效率的策略以生产再生饮用水至关重要。