生物磁小体活化过硫酸盐原位修复PAHs污染地下水研究

Many studies focus on in-situ remediation of organic polluted groundwater, but it is still hard to treat non-biodegradation organics. Advanced chemical oxidation method especially activation of persulfate to form sulfate radicals (SO4-o) is a potential tool for the remediation of non-biodegradation organics . But the materials which is proper to activate persulfate in aquifer has not been studied clearly. The key point of using persulfate for advanced oxidation technology is to activate persulfate to generate persulfate radical. The objective of this study is to develop a in-situ reaction zone technology to remediate polluted groundwater by activating sulfate with magnetosome, because of its excellent features of cheap, environment-friendly and high activated performance. The major research topics include: PAHs decomposition mechanisms of activated persulfate by magnetosome; the migration and transformation mechanisms of magnetosome and persulfate; the major controlling factors impacted on PAHs removal; the PAHs removal ability of activated persulfate with magnetosome; the variation characteristics of geochmicals situation and microbial community. The findings of this project will provide strong theory support for the developing of in-situ remediation technologies in non-biodegradable organics polluted groundwater.

地下水有机污染的原位修复是目前国际上研究的热点和前沿，但难生物降解有机污染物的原位修复仍存在一定困难。高级化学氧化方法受到青睐，活化过硫酸盐原位化学氧化就是其中最有效的方法之一，但适用于地下水环境污染修复的活化方法尚待开发。本项目基于生物源磁性纳米颗粒-磁小体具有廉价、环境友好、活化性能高的优良特性，拟对磁小体活化过硫酸盐的PAHs污染地下水原位反应带修复方法进行研究。揭示磁小体活化过硫酸盐氧化降解PAHs的机理；明确磁小体和过硫酸盐在地下环境中的传质过程和原位反应带的分布规律；识别影响PAHs去除的主控因素；阐明利用磁小体活化过硫酸盐原位修复PAHs污染地下水的效能及引起的微生态效应。本项目的研究对开发地下水难降解有机污染物去除的实用性新技术具有理论指导意义。

本项目基于生物源磁性纳米颗粒-磁小体具有分散性优异、活化性能高的优良特性，通过筛选、分离和培养获得了趋磁细菌及生物磁小体，考察了其结构、形态及组成，并研究了其活化过硫酸盐的能力。为改善磁小体产量有限等问题，研发了人工合成的类生物磁小体-茶皂素(Saponin)改性纳米Fe3O4，S-Fe3O4的分散性能很好，较Fe3O4其活化性能还得到了大大提高。影响污染物降解的主控环境因素研究结果表明地下水中常见离子Mg2+、Ca2+、Cl-、HCO3-、NO3-和SO42-对S-Fe3O4活化过硫酸盐去除污染物效能影响较大的离子为Cl- 和HCO3-，原因是这两种离子会淬灭硫酸根自由基。而Ca2+有影响但较小的原因是CaSO4为微溶于水的沉淀，沉积在活化剂的表面，遮盖了部分的活化位点。另外还研究明确了类磁小体在地下环境中的传质过程和分布规律。未改性的Fe3O4经一次性注入后会立即堵塞在注入口处，此后尽管以1 m/d的地下水流速进行冲刷，材料也几乎不能继续迁移。而S- Fe3O4则随着注入的开始就即刻在模拟柱内发生迁移现象，然后随着1m/d的地下水流速会继续迁移，直至迁移到模拟柱的最顶端，从顶端出水口流出。总之人工构建的类生物磁小体不仅性能稳定、活化能力高、而且迁移及修复性能良好，是具有广阔前景及实用价值的新型修复材料，基于磁小体的地下水难降解有机污染物的高级氧化原位修复技术具有重要的价值和意义。