Efficiency analysis of enhanced Sb(V) removal via dynamic preloaded floc in coordination with ultrafiltration

Abstract

Sb(V) can cause chronic or acute poisoning to animals and plants; Unfortunately, traditional coagulation–flocculation–sedimentation (CFS) process has limited effect on Sb removal. In this study, flocs produced by CF process were preloaded on the surface of the UF membrane, and the coordinated coagulation-floc preloaded-ultrafiltration (CFPLU) process was proposed. The removal effect of the CFPLU process on composite pollutants and the fouling degree of the UF membrane were studied under different solid contents of floc-preloaded water samples. Moreover, the removal mechanism of Sb(V) and membrane fouling mechanism in CFPLU process were also investigated. The results indicated that, compared with the CFS process, UF process, CF ultrafiltration (CF-UF) process, preloaded UF (PL-UF) process, the CFPLU process has the highest removal rate for Sb(V) and the lowest degree of membrane fouling. When the solid content is 1.5%, Sb(V) removal rate reaches the highest value of 97.29% and Sb(V) concentrations of CFPLU under all solid contents are < 5 μg/L and. The preloaded floc layer on the surface of UF membrane has adsorption and interception effects generated via electrostatic forces and chemical bonds. Furthermore, the preloaded floc layer can serve as a barrier toward the surface of the UF membrane, and then reduce the chance of the UF membrane-contacting contaminants such that membrane fouling is effectively alleviated. Thus, the CFPLU process not only enhances the removal of contaminants and mitigates membrane fouling but also provides new ideas for disposing coagulated sludge, which reduces the energy consumption of sludge disposal and realizes resource utilization.