Performance of biological ion exchange resin and gravity-driven ceramic membrane hybrid process for surface water treatment

In this study, the performance of a biological ion exchange (BIEX) resin and gravity-driven ceramic membrane (GDCM) filtration hybrid process in terms of membrane permeate quality, flux, and membrane biofilm characteristics during river water treatment for drinking water was investigated. The hybrid process results were compared with those of the GDCM process without the BIEX pre-treatment. Three types of previously synthesized microfiltration membranes were used: M1 (100 wt% kaolin), M2 (75 wt% kaolin + 25 wt% alumina), M3 (50 wt % kaolin + 50 wt% alumina), and M4 (commercial ceramic microfiltration membrane). In terms of permeate quality, the BIEX column removed approximately 74 % of the dissolved organic carbon (DOC) compared with the influent water, followed by 27 % DOC removal using M3 compared with the BIEX column effluent on day 65 (6,240 BV), which was mainly due to the removal of humic and fulvic acids. BIEX removed turbidity of the influent water from 2.20 NTU to 0.77 NTU, which was further decreased to 0.09 NTU by membranes. The maximum stabilized flux of the membranes was approximately 5.7 LMH, which was almost doubled compared to GDCM without pre-treatment. The membrane biofilm showed lower thickness and roughness in the hybrid process than that in GDCM without pre-treatment. Higher extracellular polymeric substance (EPS) concentration and biological activity were observed for M3, the membrane with the highest stabilized flux and highest DOC removal efficiency. The results indicate that the hybrid BIEX + GDCM is a robust, high-performance, and easy-touse process that can increase the flux and permeate quality of GDCM systems.