Abstract
The biofilm culturing device fixed on the slides was vertically placed in the commonly called small Li Lake of Jiangnan University. The adsorption experiment of Cu2+ was carried out by mature biofilm. Besides, scanning electron microscope (SEM), polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy spectrum (SEM-EDX) were used to analysis the effect of Cu2+ on the morphological structure of biofilm. The result indicated that when the initial concentration of Cu2+ was 5 mg·L-1, the absorption capacity of Cu2+ by unit mass biofilm is the maximum. More extracellular polymeric substances (EPS) were released by biofilm due to the stimulation of Cu2+. EPS was beneficial to the adsorption of Cu2+ by biofilm. After the adsorption of Cu2+, the bacterial diversity index decreased, while there were no significant differences in microbial communities on biofilm. Moreover, the main groups combining Cu2+ were the hydroxyl groups and amide groups in S-EPS and B-EPS. Ion exchange is a mechanism of the adsorption of Cu2+ by EPS.
Highlights
In recent years, the river contamination in China was serious, which led to degradation of the river ecosystems and deterioration of water quality
A large number of studies has shown that the extracellular polymeric substances (EPS) had a strong adsorption capacity of heavy metal ions, Liu et al ( ) indicated that removal efficiency of Zn2þ, Cu2þ and Cr2þ by EPS was above 95%
The biofilm samples cultured for 21 days were observed the morphology of biofilm under optical microscope and transmission electron microscope (TEM)
Summary
The river contamination in China was serious, which led to degradation of the river ecosystems and deterioration of water quality. Huang et al ( ) investigated that pH had a significant effect on the adsorption of biofilms It indicated that the adsorption capacity of Cu by biofilms reached the maximum (161.80 μg/g) when the pH value was 5. A large number of studies has shown that the EPS had a strong adsorption capacity of heavy metal ions, Liu et al ( ) indicated that removal efficiency of Zn2þ, Cu2þ and Cr2þ by EPS was above 95%. Water Science & Technology | 78.4 | 2018 and 0.50 mg/g EPS for the three heavy metal ions, which investigated the adsorption efficiency of EPS on Cu2þ, Cr3þ and Ni2þ. The experiments on the purification and adsorption of heavy metals by biofilms were mostly concentrated on deleterious Pb and Cd (Duong et al ), while the trace element copper was less studied. SEM, PCR-DGGE, FTIR and SEM-EDX were used to discuss the effect of Cu2þ on the morphological structure of biofilm
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