State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), School of Environment, Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin 150090, PR China; Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; Livinguard AG, Bahnhofstrasse 12, 6300 Zug, Switzerland.
Sci Total Environ. 2021 May 10;768:144758. doi: 10.1016/j.scitotenv.2020.144758. Epub 2020 Dec 31.
As a low-maintenance and cost-effective process, gravity-driven membrane (GDM) filtration is a promising alternative for decentralized drinking water supply, while the low flux impedes its extensive application. In order to address such issue, an integrated process consisting of granular activated carbon (GAC) layer and GDM was developed. The performance of virgin (fresh GAC) or preloaded GAC (saturated GAC) was compared. Flux stabilization was observed both in the fresh and saturated GAC/GDM process during long-term filtration and their stable fluxes were both improved by approximately 50% relative to the GDM control. Moreover, integrating GAC with GDM contributed to efficient removals for dissolved organic compounds (DOC), assimilable organic carbon (AOC) and low molecular weight substances both in fresh and saturated GAC/GDM filtration. Compared to GDM control, coupling GAC to GDM could significantly reduce the concentrations of extracellular polymeric substances (EPS) and total cell counts (TCC) within the biofouling layer, and engineer highly heterogeneous structures of biofouling layer on the membrane surface. In the fresh GAC/GDM process, the improved flux obtained was mainly related to less coverage of biofouling layer and lower EPS concentrations due to efficient removals of membrane foulants by GAC adsorption. The achieved higher stable flux can be maintained during long-term filtration (after GAC saturation) owing to the combined effects of EPS reduction and formation of highly heterogeneous structures of biofouling layer in the saturated GAC/GDM system. Overall, the integrated GAC/GDM process can hopefully facilitate improvements both in the stabilized flux and permeate quality, with practical relevance for GDM applications in decentralized drinking water supply.
作为一种低维护和具有成本效益的过程，重力驱动膜（GDM）过滤是分散式饮用水供应的一种很有前途的替代方案，但其通量低阻碍了其广泛应用。为了解决这个问题，开发了一种由颗粒活性炭（GAC）层和 GDM 组成的集成工艺。比较了新鲜（新鲜 GAC）或预加载 GAC（饱和 GAC）的性能。在长期过滤过程中，新鲜和饱和 GAC/GDM 过程中都观察到通量稳定，其稳定通量相对于 GDM 对照均提高了约 50%。此外，将 GAC 与 GDM 集成有助于在新鲜和饱和 GAC/GDM 过滤中有效去除溶解有机物（DOC）、可同化有机碳（AOC）和低分子量物质。与 GDM 对照相比，将 GAC 与 GDM 结合可以显著降低生物污垢层内的胞外聚合物物质（EPS）和总细胞计数（TCC）的浓度，并在膜表面形成高度不均匀的生物污垢层结构。在新鲜 GAC/GDM 过程中，获得的改善通量主要与生物污垢层的覆盖度降低和 EPS 浓度降低有关，这是由于 GAC 吸附对膜污染物的有效去除。在长期过滤（GAC 饱和后）过程中可以保持较高的稳定通量，这是由于在饱和 GAC/GDM 系统中 EPS 减少和生物污垢层形成高度不均匀结构的综合作用。总的来说，集成的 GAC/GDM 工艺有望在稳定通量和渗透水质方面都有所提高，对分散式饮用水供应中 GDM 的应用具有实际意义。
