Multifunctional modified polyvinyl alcohol: A powerful biomaterial for enhancing bioreactor performance in nitrate, Mn(II) and Cd(II) removal

Abstract

The co-existence of multiple pollutants in wastewater such as nitrate and heavy metal, is of high concern due to the potential environmental impact. In this study, a novel biomaterial PPy@Fe3O4/PVA was synthesized as a multifunctional bacteria immobilized carrier, to enhance simultaneous denitrification, Cd(II) and Mn(II) removal efficiency in bioreactor environments. The morphology and main components of the PPy@Fe3O4/PVA material were characterized by SEM and XRD. Using PPy@Fe3O4/PVA as a carrier, the maximum removal efficiencies for nitrate (0.207 mg L−1·h−1), Mn(II) (90.98%) and Cd(II) (98.78%) were increased by 27.05%, 30.27%, and 16.48%, respectively, compared to in the absence of PPy@Fe3O4/PVA. Regeneration experiments were performed, demonstrating the excellent stability and reusability of the PPy@Fe3O4/PVA material. Furthermore, effects of key factors were investigated on the performance of the PPy@Fe3O4/PVA bioreactor in simultaneous denitrification, Mn(II) and Cd(II) removal. Experimental results indicate that the highest nitrate, Mn(II) and Cd(II) removal efficiencies were obtained under the conditions of HRT of 10 h, initial Mn(II) concentration of 40 mg/L and initial Cd(II) concentration of 10 mg/L. Gas chromatography analysis indicated that N2 was the mainly final gaseous product. Moreover, the bioreactor community diversity was markedly influenced by the initial concentration of Cd(II) and Pseudomonas sp. H117 played a primary role in the process of simultaneous denitrification, Mn(II) and Cd(II) removal.