River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
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.
Chemosphere. 2020 Feb;241:125035. doi: 10.1016/j.chemosphere.2019.125035. Epub 2019 Oct 3.
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 for Cd(II), Pb(II) and 1-100 mg L 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, while Rhodanobacter thiooxydans resisted to all heavy metal concentrations except Cu(II) 100 mg L. 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.
重金属在特定浓度下对微生物有毒，会对生物废水处理厂的效率产生严重影响。在 30 天的时间内，在一个控制良好的半连续反应器中，研究了不同重金属浓度（Cd(II)为 0.1-10mg/L，Pb(II)为 1-100mg/L，Cu(II)）下活性污泥的废水处理性能和细菌群落。在整个实验过程中，每 8 小时添加一次葡萄糖作为碳源。重金属毒性与化学需氧量（COD）、总有机碳（TOC）、三维荧光激发-发射矩阵（EEM）光谱、细菌活性和群落组成有关。与对照相比，葡萄糖的一级消耗速率表明活性在下降。在所有不同重金属浓度处理的反应器中，COD 去除效率也从 87%下降到 26%。PCR-DGGE 和测序结果表明，由于重金属的潜在毒性，细菌多样性在重金属胁迫下表现出明显的变化。在属水平上，只有 Pedobacter steynii 和 Flavobacterium 能够耐受 100mg/L 的 Cu(II)，而 Rhodanobacter thiooxydans 能够耐受除 100mg/L Cu(II)以外的所有重金属浓度。聚类分析和主成分分析（PCA）表明，Cu(II)处理的微生物群落与 Cd(II)和 Pb(II)浓度处理的污泥样本不同。该研究表明，有必要确定耐金属细菌的种类，以维持生物废水处理厂的良好性能。
