产表面活性剂菌对焦化废水中多环芳烃好氧生物降解的增效机制

Coking industrial wastewater is characterized by high organic carbon content and extremely high concentrations of polycyclic aromatic hydrocarbons (PAHs). Majority of the PAHs are bound on sludge particles and cannot be removed via aerobic biodegradation processes. They are often discharged along with sludge, possessing high environmental risk. It is known that certain bacteria in wastewater treatment systems can produce surfactant-like biomolecules while also utilizing hydrophobic organic compounds as their carbon sources. These microorganisms are much preferred in treating coking wastewater as the secreted biosurfactants can enhance the aqueous solubility of PAHs, indirectly promote mass transfer processes for the sludge bound PAHs, and hence potentially increase the rates of PAHs degradation and improve the efficiency of coking wastewater treatment. This project aims to add surfactant-producing bacteria labeled with green fluorescent protein into the coking wastewater during aerobic treatment process. We will use microbial high-throughput sequencing technology and advanced detection technology for environmental microbiological analysis. We will quantify the effects of microbial community on PAHs biodegradation by surfactant-producing bacteria and will analyze the role of the different types of microflora in PAHs removal. Special attention will be paid to different physicochemical factors that may promote or inhibit surfactant-producing microflora and the microbial communities for degrading PAHs in the wastewater- treatment system. The optimal microbial community structure and preferred operational conditions will be sought for most efficiently degrading sludge bound PAHs. The ultimate goal of this project will be to maximize biological reduction of PAHs within the coking wastewater treatment system, hence reducing the PAHs concentrations in the discharged sludge. The study will be an example of implementation of functional microbial community for treating targeted pollutants in wastewater industry.

以疏水性有机物占主导的焦化废水，多环芳烃（PAHs）含量高，易被污泥吸附难以实现生物降解，其主要归趋为污泥的富集作用，普遍的浓度达到3-10 g/kg干污泥的水平，环境风险非常高。表面活性剂产生菌能利用废水中疏水性有机物分泌表面活性剂从而增溶PAHs，提高PAHs传质及生物降解效率。项目拟在焦化废水好氧处理阶段投加有绿色荧光蛋白分子标记的产表面活性剂菌种，利用微生物高通量测序技术及环境分析先进检测技术，研究产表面活性剂菌群加入后的生态效应演变及对PAHs生物降解的影响；分析不同类型菌群在焦化废水处理中的角色/功能，寻找表面活性剂菌群和多环芳烃降解菌群在废水处理系统中的相互促进或制约因子；寻求PAHs生物降解最佳效率的菌群构成及运行条件，实现煤焦化废水PAHs的原位生物削减，大幅度降低外排污泥的PAHs含量。构建从微生物功能水平上实现废水中靶向污染物（如PAHs）有效去除的方法学案例。

以疏水性有机物占主导的焦化废水，多环芳烃（PAHs）含量高，易被污泥吸附难以实现生物降解，环境风险非常高。表面活性剂产生菌能利用废水中疏水性有机物分泌表面活性剂而增溶PAHs，提高PAHs传质及生物降解效率。本项目利用焦化废水中筛选的土著产表面活性剂菌Pseudomonas aeruginosa S5，原位强化焦化废水中PAHs的生物降解，研究了S5加入后对PAHs生物降解的影响及污泥群落结构演变、S5菌和PAHs降解菌群在废水处理系统中的促进/制约因子。主要研究结果如下：.（1）S5菌和PAHs降解菌混合培养，促进了PAHs降解菌对PAHs的降解效率，对大于5环的PAHs，降解率提高了3.5-4倍，表现出很强的协同增效作用。针对实际焦化废水，用O1/H/O2生物流化床处理工艺，在O1和O2阶段投分别加污泥比10%的产表面活性剂细菌S5，与对照组相比去，整个工艺的PAHs去除率增加了4倍。.（2）S5接种之后对污泥微生物群落门水平的演变影响不大，但对属水平上微生物的结构演变影响较大，提高了污泥中PAHs及大分子有机物降解菌属的相对丰度。在S5接种浓度为10%时，与 PAHs降解代谢通路相关的功能基因相对丰度最高；其中PAH-RHDa GN基因拷贝数随S5接种浓度的增加而增加；相对于游离接种，S5固定化后接种到实际焦化废水中可以提高PAHs的降解。.（3）焦化废水原水中的大宗污染物苯酚抑制S5的生长，但可以增加每单位菌体对PAHs的溶解浓度，因而苯酚的存在可以促进PAHs降解，在低COD的O2工段，葡萄糖碳源的添加也有利于S5的生长及PAHs的削减。.研究确定了PAHs生物降解最佳效率的菌群构成及运行条件，提高了焦化废水PAHs的原位生物削减，增加了高含量PAHs废水处理中微生物群落功能菌的研究范围和群落功能角色的分类，构建了从微生物功能水平上实现PAHs有效去除的方法案例。