Effect of heavy metals on the performance and bacterial profiles of activated sludge in a semi-continuous reactor

Sartaj Ahmad Bhat; Guangyu Cui; Wenjiao Li; Yongfen Wei; Fusheng Li

doi:10.1016/j.chemosphere.2019.125035

Effect of heavy metals on the performance and bacterial profiles of activated sludge in a semi-continuous reactor

Chemosphere. 2020 Feb:241:125035. doi: 10.1016/j.chemosphere.2019.125035. Epub 2019 Oct 3.

Authors

Sartaj Ahmad Bhat¹, Guangyu Cui², Wenjiao Li³, Yongfen Wei⁴, Fusheng Li⁵

Affiliations

¹ River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan. Electronic address: sartajbhat88@gmail.com.
² River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan; State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, 200092, China.
³ Graduate School of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
⁴ River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
⁵ River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan; Graduate School of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.

PMID: 31606576
DOI: 10.1016/j.chemosphere.2019.125035

Abstract

Heavy metals are toxic to microorganisms at specific concentrations and can have a serious effect on the efficiency of biological wastewater treatment plants. The wastewater treatment performance and bacterial communities of activated sludge were investigated at different heavy metal concentrations (0.1-10 mg L^-1 for Cd(II), Pb(II) and 1-100 mg L^-1 for Cu(II)) in a well-controlled semi-continuous reactor in 30 d period. Glucose was added once every 8 h as the carbon source throughout the experiment. The heavy metal toxicity was related to chemical oxygen demand (COD), total organic carbon (TOC), three-dimensional fluorescence excitation-emission matrix (EEM) spectroscopy, bacterial activity and community composition. The first-order consumption rate for glucose showed that the activity was decreasing in comparison to the control. The COD removal efficiency was also decreased from 87% to 26% in all the reactors under different heavy metal concentrations treatment. The PCR-DGGE and sequencing results revealed that the bacterial diversity showed evident variations under heavy metal stress owing to the potential toxicity of heavy metals. At the genus level, Pedobacter steynii and Flavobacterium, were only tolerant to Cu(II) at 100 mg L^-1, while Rhodanobacter thiooxydans resisted to all heavy metal concentrations except Cu(II) 100 mg L^-1. Cluster analysis and Principal component analysis (PCA) revealed that the microbial community in Cu(II) was different from the sludge samples treated with Cd(II) and Pb(II) concentrations. The study indicated that it is necessary to identify the metal tolerant species of bacteria for maintaining good performance of biological wastewater treatment plants.

Keywords: Activated sludge; Heavy metals; Microbial community; Toxicity.

MeSH terms

Bacteria / drug effects*
Bioreactors*
Drug Resistance, Bacterial
Metals, Heavy / analysis
Metals, Heavy / toxicity*
Microbiota / drug effects
Sewage / chemistry
Sewage / microbiology*
Wastewater / analysis
Water Purification

Substances

Metals, Heavy
Sewage
Waste Water