过硫酸钠化学氧化预处理强化原位微生物修复土壤石油污染

Combining in situ chemical oxidation (ISCO) and in situ bioremediation (ISB) is one of the primary methods for treatment of petroleum-contaminated soil. ISCO can improve biodegradation by reducing contaminant concentrations to less toxic levels, by improving their availability, and by augmenting the mobilized nutrients. Sodium persulfate (PDS) is a promising oxidant for ISCO in soil due to the relative long half-life, large diffusion radius and the generated sulfate radical as a highly reactive species. However, compared with traditional oxidants (H2O2 and KMnO4), PDS showed much higher inhibition of indigenous microbial community also due to its persistence that could keep releasing sulfate radical to kill the microbes. To date, few studies have nevertheless been focused on the contradictory effects of PDS on microbial activity during remediation of petroleum-contaminated soil by ISCO-ISB. Controlling the releasing rate of sulfate radical by stepwise adding PDS or by using less efficient catalyst would decrease the destruction effects on microbes. Adding nutrients would stimulate the growth of indigenous microbes. Thus, this project will work on reducing the inhibition of PDS on soil microbial viability via regulating the operation conditions, or using different catalysts, or adding nutrients. Total petroleum hydrocarbons (TPH), total numbers of bacterial, microbial community structure and diversity will be determined under different conditions. Interaction mechanism between different PDS operation conditions and microbes will be proposed. Techniques for enhancing TPH removal and reducing the costs will be provided with consideration of final TPH removing rates and costs of all chemicals at different conditions. The successful completion of the proposed project will provide theoretical guidance for achieving effective ISCO-ISB performance with PDS at relative low cost for the remediation of petroleum-contaminated soil.

原位化学氧化(ISCO)与原位微生物修复(ISB)联合使用是修复石油污染土壤的主要手段之一。ISCO能降低石油烃的生物毒性、增加生物可利用性，促进ISB过程。过硫酸钠(PDS)在土壤中活性持续时间长、生成的硫酸根自由基氧化性强，对土壤有机污染物去除效果好，但其对土壤微生物的灭活作用远大于过氧化氢和高锰酸钾等氧化剂，不利于ISB处理。目前，国内外对调控和平衡PDS在ISCO-ISB修复中对土著微生物的“矛盾”作用研究较少。本项目拟通过改变PDS反应操作条件与外加不同催化剂以调控硫酸根自由基生成速率、添加营养物质刺激微生物生长，进而调节对土壤微生物的抑制作用，比较不同操作方式对细菌数量、群落结构和多样性的影响，结合TPH去除率，构建促进ISCO-ISB修复效果和降低成本的强化方法。为提升PDS用于ISCO-ISB联合处理石油污染土壤的修复效率和降低成本提供研究思路和技术支持。

原位化学氧化(ISCO)与原位微生物修复(ISB)联合使用是修复石油污染土壤的主要手段之一。ISCO能降低石油烃的生物毒性、增加生物可利用性，促进ISB过程，但ISCO同时对土壤微生物具有灭活作用，不利于ISB处理。.本项目针对氧化处理在ISCO-ISB修复石油污染土壤中对土著微生物的“矛盾”作用，采用H2O2、Na2S2O8在不同浓度、投加方式、外加催化剂、氮磷营养物质等条件下氧化处理石油污染土壤，监测反应体系中总石油烃（TPH）、氧化剂剩余量、pH、总水溶性营养物质（DOC、TN、TP）含量，通过高通量测序分析细菌群落结构和多样性，阐明各条件下TPH去除率、细菌群落结构和多样性与各环境因素的相关关系，构建促进ISCO-ISB修复效果和降低成本的强化方法。取得了以下3点重要结果，以期为提升ISCO-ISB联合处理石油污染土壤的修复效率和降低成本提供研究思路和技术支持。.（1）Na2S2O8在土壤中存留时间和对TPH的降解效果均优于H2O2。外加催化剂ZVI提高Na2S2O8在土壤中的持续有效性，显著促进了TPH持续降解和总降解率。分批次投加低浓度H2O2显著提高了对TPH的去除率。氧化处理使得石油烃长链烷烃变为较短链烷烃。.（2）在同等浓度氧化剂条件下，整个反应期间H2O2处理中DOC浓度远高于Na2S2O8处理；TN在Na2S2O8处理中的浓度显著高于H2O2处理和对照。在反应中后期需根据情况补充N、P营养物质，以给微生物恢复生长提供合适的C、N、P比例。.（3）不同氧化处理和反应培养时间均对土壤细菌群落结构具有重要影响。TPH含量相近的土壤拥有相似的物种组成结构；TP对Na2S2O8处理中细菌群落分布具有显著影响，但对H2O2处理中细菌群落分布无显著影响。在反应第0天添加N、P对土壤细菌群落结构变化的影响较小，而在反应第5天添加N、P可显著促进后续优势微生物的恢复，对通过添加营养物质刺激土壤细菌群落的恢复具有一定指示意义。.