Abstract

Activated carbon cloths (ACCs) were used as biofilms supports in the anaerobic biotransformation of 4-nitrophenol (4NP). As received ACC material (AW) was oxidized with HNO₃ (OX) and then functionalized with anthraquinone-2,6-disulfonate (AQ). The three ACCs were packed in hybrid UASB reactors and seeded with anaerobic granular sludge for biotransformation experiments. The results indicated that ACC-packed bioreactors improved the biotransformation of 4NP by twofold as compared to the control reactor without support materials. However, the biotransformation effciency of AW, OX and AQ was very similar (59%), indicating the role of ACC as biofilm support and not as redox mediator. After 4NP biotransformation several physicochemical and biological changes were observed like (1) the point of zero charge (pH_PZC) shift from acidic values (AW = 5.0, OX = 3.4, AQ = 3.1) to neutral values (pH_PZC = 7.6 on average), (2) increase in the concentration of acidic and basic surface functional groups over ACC materials and the amount of supported biomass on ACCs due to biofilm formation, and (3) enrichment of exoelectrogenic microorganisms belonging to the genera Geobacter over carbonyl-rich ACC surface as revealed by 16S rRNA amplicon sequencing. Overall, the results suggest that chemical modifications of ACCs changed the microbial composition of the biofilm, but the higher concentration of carbonyl groups on ACC did not affect the biotransformation of 4NP.

Graphic Abstract

中文翻译：

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由于4-硝基苯酚的生物转化中活性炭布的表面化学修饰不同，生物膜微生物组成也会发生变化。

摘要

活性炭布（ACC）用作4-硝基苯酚（4NP）厌氧生物转化中的生物膜载体。收到的ACC材料（AW）用HNO ₃（OX）氧化，然后用2,6-二磺酸蒽醌（AQ）官能化。将三种ACC装在UASB混合反应器中，并接种厌氧颗粒污泥以进行生物转化实验。结果表明，与没有载体材料的对照反应器相比，装有ACC的生物反应器将4NP的生物转化提高了两倍。但是，AW，OX和AQ的生物转化效率非常相似（59％），表明ACC作为生物膜支持物而不是氧化还原介质的作用。经过4NP生物转化后，观察到一些物理化学和生物学变化，如（1）零电荷点（pH_PZC）从酸性值（AW = 5.0，OX = 3.4，AQ = 3.1）转变为中性值（pH _PZC  =平均7.6），（2）与ACC材料相比，酸性和碱性表面官能团的浓度增加（16）rRNA扩增子测序表明，由于生物膜形成，ACC上受支持的生物质的量增加；（3）富含羰基的ACC表面富集属于Geobacter属的外生电微生物。总体而言，结果表明ACC的化学修饰改变了生物膜的微生物组成，但ACC上较高的羰基浓度并未影响4NP的生物转化。

图形摘要