Humic Acid can Enhance the Mineralization of Phenanthrene Sorbed on Biochars.

Biodegradation of hydrophobic organic contaminants by bacteria has been widely studied, but how dissolved organic matter (DOM) may affect their removal if accumulated on biochars is poorly understood. To address this knowledge gap, microbial mineralization of phenanthrene (PHE) spiked on various biochars by Mycobacterium vanbaalenii PYR-1 in the presence of humic acid (HA, a model DOM) at two concentrations was investigated. Our findings showed that HA greatly increased the rate and extent of PHE mineralization. This could be attributed to enhanced PHE desorption by HA which facilitated access to it by bacteria in the aqueous phase. Furthermore, the high HA affinity for PHE facilitated PHE flow towards the bacterial cells with HA acting as a carrier in the aqueous phase. The mineralization enhancement of PHE by HA within 480 h was negatively influenced by the aromatic carbon contents and micropore volumes in biochars. This shows the importance of the physicochemical properties of biochars in altering the HA effect. Results of this study provide novel information on how to achieve complete removal of PHE accumulated on biochars with a strong sorption affinity for it, using a microbial technique and natural DOM.

细菌对疏水性有机污染物的生物降解已被广泛研究，但对于溶解有机物（DOM）如果在生物炭上积累会如何影响其去除却知之甚少。为了填补这一知识空白，研究了在两种浓度的腐殖酸（HA，一种DOM模型）存在下，范氏分枝杆菌PYR - 1对添加在各种生物炭上的菲（PHE）的微生物矿化作用。我们的研究结果表明，HA极大地提高了PHE矿化的速率和程度。这可能归因于HA增强了PHE的解吸，从而有利于细菌在水相中获取PHE。此外，HA对PHE的高亲和力促进了PHE向细菌细胞流动，HA在水相中起到了载体的作用。在480小时内，HA对PHE矿化的增强作用受到生物炭中芳香碳含量和微孔体积的负面影响。这表明了生物炭的物理化学性质在改变HA效应方面的重要性。这项研究的结果为如何利用微生物技术和天然DOM完全去除在对其具有强吸附亲和力的生物炭上积累的PHE提供了新的信息。