Mixed pollution of nitrate, tetracycline (TC) and cadmium (Cd2+) induced by improper discharge of various wastewater from industry and agriculture has attracted extensive attention. A novel biocarrier (MBF@FMJSB) assembled with modified basalt fiber and modified wild jujube seed biochar (FMJSB) was used to construct fixed-biofilm reactor (FBR) for concurrent removal of nitrate, TC, and Cd2+. The removal efficiencies of nitrate, TC, and Cd2+ of the bioreactor were 79.34%, 85.45%, and 88.02%, respectively, when HRT was 6.0 h, C/N ratio was 1.5, influent nitrate concentration was 25 mg L-1, pH was 6.5, and TC and Cd2+ concentrations was 0.6 and 1 mg L-1. The addition of FMJSB was not only beneficial for bacteria to resist the stress of TC and Cd2+, but also contributed to the removal of TC and Cd2+ pollutants. In addition, microbial metabolism was a key pathway for pollutant removal in FBR. Microflora with Zoogloea as a core genus can dynamically regulate the community structure and expression of microbial metabolism related genes to adapt to TC and Cd2+ stresses. This study was valuable for the treatment of wastewater containing mixed pollutants.
