固态腐殖质作为电子受体强化苯系物厌氧微生物降解的研究

Anaerobic biodegradation of BTEX proceeds very slowly due to the limitation of electron acceptor in contaminated aquifer. The liquid reagents traditionally used for enhancing this process readily migrate away from the contaminated site while continuous addition of them would cause secondary pollution of the groundwater. In our previous study, we found that the anaerobic biodegradation of toluene was enhanced by solid-phase humic substances (humin), which are abundant and ubiquitous in the environment. However，the universality for the enhancement of other BTEX compound biodegradation has not been verified and the detail mechanism has not been determined yet. In this study, we will examine the feasibility of using solid-phase humin for biodegradation of BTEX compounds instead of the traditionally used liquid reagents. The role of humin during this process will also be determined. Benzene is selected as a representative BTEX compound due to its environmental persistence and high toxicity. Humin will be added to the enriched anaerobic BTEX degradation culture, to study the enhancement effects on BTEX biodegradation by means of examining the degradation metabolites、degradation rates and the response of microbial community. Furthermore, the role and effectiveness of using solid-phase humin will be resolved by gradually decreasing the use of liquid reagents to finally make the humin as the sole electron acceptor. After the optimization of biodegradation conditions，the functional microorganisms involved in the BTEX biodegradation process and the electron accepting moieties in the humin will be identified, and their relations will be established for exploring the electron transfer mechanisms between microorganisms and humin. This project will provide solid scientific basis for effective bioremediation of BTEX contaminated groundwater with an alternative and engineering favored material.

由于电子受体的缺乏，污染含水层中苯系物（BTEX）的厌氧降解速率非常缓慢。常规的用于强化该过程所使用的液态电子受体易流失，而连续添加又会造成二次污染。我们前期研究发现自然界中广泛分布的固态腐殖质可以强化甲苯的厌氧降解，但这种强化作用的普适性及强化机理尚不清楚。因此，本项目将以BTEX中毒性最强且难降解的苯为研究对象，探索使用固态腐殖质代替液态电子受体强化BTEX厌氧降解的可行性及机理。通过向BTEX厌氧降解菌群中添加固态腐殖质，研究其对BTEX降解效果的强化及相应的微生物群落响应。在此基础上，利用固态腐殖质逐步取代液态电子受体，进一步明确其在强化过程中起到了电子受体的作用。优化降解条件，识别BTEX降解功能微生物及固态腐殖质电子接受功能组分，并阐明二者之间的关系，进而探究功能微生物与固态腐殖质之间的电子传递机理。研究成果将为提高BTEX污染地下水生物修复效率提供可靠的理论基础和科学依据。

由于电子受体的缺乏，污染含水层中苯系物（BTEX）的厌氧降解速率非常缓慢。我们前期研究发现自然界中广泛分布的固态腐殖质在有硝酸盐存在的条件下可以强化苯系物的厌氧降解。本研究通过向不含有硝酸盐的甲苯厌氧降解菌群中添加固态腐殖质，发现甲苯依然能够降解同时胡敏素的还原力也增大了，说明胡敏素可能作为微生物呼吸的电子受体驱动了甲苯的氧化。由于苯的厌氧降解非常困难，受很多因素影响。我们在富集胡敏素依赖苯厌氧降解微生物的基础上，通过响应面曲线法对苯的厌氧降解条件进行了优化，发现苯的初始浓度对苯的厌氧降解效率影响最大，而溶解氧浓度在0.8 mg/L以下时对苯的厌氧降解影响不大。最后，我们通过分析化学还原前后胡敏素光谱特征的变化及利用微生物培养的近似方法，发现醌基是胡敏素主要的电子接受功能组分之一。本研究可为提高BTEX污染地下水生物修复效率提供可靠的理论基础和科学依据。