Cr(VI) removal performance and the characteristics of microbial communities influenced by the core-shell maifanite/ZnAl-layered double hydroxides (LDHs) substrates for chromium-containing surface water

Biological mechanisms for Cr(VI) removing induced by ZnAl-LDHs coated on maifanite substrate were explored in constructed rapid infiltration systems (CRIS). Characteristics of maifanite/ZnAl-LDHs and natural maifanite by scanning electron microscope (SEM) and X-ray fluorescence spectrometer (XRF) confirmed the feasibility of the LDHs coating way. The purification experiments showed that the CRIS with maifanite/ZnAl-LDHs substrate displayed higher Cr(VI) removal performance induced by microorganism than that with natural maifanite. High throughput sequencing results of microorganism immobilized on the two substrates revealed that Methyloversatilis, Novosphingobium, Dongia and Paludibaculum were more abundant in maifanite/ZnAl-LDHs. We conclude that maifanite/ZnAl-LDHs adsorbed more Cr(VI) than natural maifanite, ZnAl-LDHs and the high Cr (VI) concentration ambient of maifanite/ZnAl-LDHs enhanced enzymatic activities and altered microbial community, which leading to higher Cr(VI) removal performance in turn. The present study may provide essential information for exploring whether the LDHs coated on natural substrate will affect the microorganism in CRIS.