Development of innovative hydrogel-GAC particles utilized in aerobic fluidized bed membrane bioreactor for enhancing high-saline organic wastewater treatment

Membrane bioreactors have been prevalently employed to treat high-saline organic wastewater. However, inadequate contaminant removal and severe membrane fouling significantly hamper their practical application. To address these challenges, this study employed an aerobic fluidized bed membrane bioreactor (AFMBR) to treat high-saline organic wastewaters based on the innovatively prepared hydrogel-granular activated carbon (GAC) composite particles, formed by calcium ions and sodium alginate (SA), acting as both biocarriers and media for membrane fouling control. The results showed that the Ca²⁺:SA ratio, pH and temperature significantly affected the properties of hydrogel-GAC particles. Compared with ordinary GAC, the biomass amount attached to hydrogel-GAC composite particle was significantly enhanced. The novel hydrogel-GAC composite particles loaded with halotolerant microorganisms were further utilized in AFMBR to treat high-saline organic wastewaters. Within 30 days of operation, the biomass amount on the particles stabilized at over 10,000 mg/L, with COD, NH₄⁺ and TN removal rates exceeding 92 %, 90 % and 76 %, respectively. Additionally, under a multi-flux operation of 5–15 L/m²·h, the transmembrane pressure in AFMBR remained at a low level, within 10 kPa without membrane cleaning. After operation, the membrane surface remained undamaged potentially due to the soft surface of hydrogel materials. Consequently, this work developed novel composite particles for use in AFMBR, achieving superior multi-pollutant removal and effective fouling control for the treatment of high-saline organic wastewater.