Zheng Xiao-Ying, Lu Dan, Wang Ming-Yang, Chen Wei, Zhou Gan, Zhang Yuan
a Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes , Hohai University , Nanjing , People's Republic of China.
b College of Environment , Hohai University , Nanjing , People's Republic of China.
Environ Technol. 2018 Jul;39(13):1682-1696. doi: 10.1080/09593330.2017.1337230. Epub 2017 Jun 12.
The frequent appearance of Cr(VI) significantly impacts the microbial metabolism in wastewater. In this study, long-term effects of Cr(VI) on microbial community, nitrogen removal pathways and mechanism of aerobic granular sludge (AGS) were investigated. AGS had strong resistance ability to 1.0 mg/L Cr(VI). 3.0 mg/L Cr(VI) increased the heterotrophic-specific ammonia uptake rate (HSAUR) and heterotrophic-specific nitrate uptake rate (HSNUR) transiently, whereas 5.0 mg/L Cr(VI) sharply decreased the specific ammonia uptake rate (SAUR), specific nitrate uptake rate (SNUR) and simultaneous nitrification denitrification rate (SNDR). It was found that Cr (VI) has a greater inhibitory effect on autotrophic nitrification (ASAUR), and the maximal inhibition rate (IR) was 139.19%. Besides, the inhibition of Cr (VI) on nitrogen removal process belongs to non-competitive inhibition. Cr(VI) had a weaker negative impact on heterotrophic bacteria compared with that on autotrophic bacteria. Denaturing gradient gel electrophoresis analyses suggest that Acidovorax sp., flavobacterium sp., uncultured soil bacterium, uncultured nitrosospira sp., uncultured prokaryote, uncultured β-proteobacterium and uncultured pseudomonas sp. were the dominant species. The inhibition of Cr(VI) on nitrite-oxidizing bacteria was the strongest, followed by ammonia-oxidizing bacteria and denitrifying bacteria. Linear correlations between bacterial count and biomass-specific uptake rate were observed when the Cr(VI) concentration exceeded 3 mg/L. This study revealed the effect of Cr(VI) on nitrification is more serious than that on denitrification. Autotrophic and heterotrophic nitrification, heterotrophic denitrification and simultaneous nitrification denitrification played a significant role on nitrogen removal under Cr(VI) stress.
六价铬（Cr(VI)）的频繁出现对废水中的微生物代谢有显著影响。本研究考察了Cr(VI)对好氧颗粒污泥（AGS）微生物群落、氮去除途径及机制的长期影响。AGS对1.0 mg/L的Cr(VI)具有较强的抗性。3.0 mg/L的Cr(VI)使异养特异性氨摄取率（HSAUR）和异养特异性硝酸盐摄取率（HSNUR）短暂增加，而5.0 mg/L的Cr(VI)则使特异性氨摄取率（SAUR）、特异性硝酸盐摄取率（SNUR）和同步硝化反硝化率（SNDR）急剧下降。研究发现，Cr(VI)对自养硝化（ASAUR）的抑制作用更大，最大抑制率（IR）为139.19%。此外，Cr(VI)对氮去除过程的抑制属于非竞争性抑制。与自养细菌相比，Cr(VI)对异养细菌的负面影响较弱。变性梯度凝胶电泳分析表明，嗜酸菌属、黄杆菌属、未培养土壤细菌、未培养亚硝化螺菌属、未培养原核生物、未培养β-变形菌属和未培养假单胞菌属为优势菌种。Cr(VI)对亚硝酸盐氧化菌的抑制作用最强，其次是氨氧化菌和反硝化菌。当Cr(VI)浓度超过3 mg/L时，观察到细菌数量与生物量特异性摄取率之间存在线性相关性。本研究表明，Cr(VI)对硝化作用的影响比对反硝化作用的影响更严重。在Cr(VI)胁迫下，自养和异养硝化、异养反硝化及同步硝化反硝化对氮去除起重要作用。
