Responses of microbial communities to single-walled carbon nanotubes in phenol wastewater treatment systems.
The expanding use of single-walled carbon nanotubes (SWCNTs) raises environmental concerns. Wastewater treatment systems are potential recipients of SWCNTs containing influent, yet the impacts of SWCNTs on these systems are poorly documented. In this study, the microbial responses to SWCNTs in simulated phenol wastewater treatment systems were investigated. The phenol removal rates were improved in all SWCNTs-treated sequencing batch reactors during the first 20 days, but when facing higher phenol concentration (1000 mg/L) after 60 days, reactors with the highest concentration (3.5 g/L) of SWCNTs exhibited a notably decreased phenol removal capacity. Cell viability tests, scanning electron microscopy analysis and DNA leakage data suggested that SWCNTs protected microbes from inactivation, possibly by producing more bound extracellular polymeric substances (EPS), which could create a protective barrier for the microbes. Illumina sequencing of 16S rRNA gene amplicons revealed that the bacterial diversity did not change significantly except for a minor reduction after the immediate addition of SWCNTs. Bacterial community structure significantly shifted after SWCNTs addition and did not recover afterward. Zoogloea increased significantly upon SWCNTs shocking. At the final stage, Rudaea and Mobilicoccus increased, while Burkholderia, Singulisphaera, Labrys and Mucilaginibacter decreased notably. The shifts of these dominant genera may be associated with altered sludge settling, aromatic degradation and EPS production. This study suggested that SWCNTs exerted protective rather than cytotoxic effects on sludge microbes of phenol wastewater treatment systems and they affected the bacterial community structure and diversity at test concentrations. These findings provide new insights into our understanding of the potential effects of SWCNTs on wastewater treatment processes.
†Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.|‡Institute for Environmental Genomics (IEG), Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019, United States.
Yuanyuan
Y
Qu
†Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.|‡Institute for Environmental Genomics (IEG), Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019, United States.
Qiao
Q
Ma
‡Institute for Environmental Genomics (IEG), Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019, United States.
Jie
J
Deng
†Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
Wenli
W
Shen
†Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
Xuwang
X
Zhang
‡Institute for Environmental Genomics (IEG), Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019, United States.
Zhili
Z
He
‡Institute for Environmental Genomics (IEG), Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019, United States.
Joy D
JD
Van Nostrand
†Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
Jiti
J
Zhou
‡Institute for Environmental Genomics (IEG), Department of Microbiology and Plant Biology, University of Oklahoma, Norman, Oklahoma 73019, United States.|§Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.|⊥State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
Jizhong
J
Zhou
D064307:Microbiota / Q000187:drug effects* / Q000502:physiology; D037742:Nanotubes, Carbon / Q000633:toxicity*; D019800:Phenol / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D037742:Nanotubes, Carbon; D019800:Phenol; D062065:Wastewater; D014874:Water Pollutants, Chemical