电动-微生物修复对胶质结构的改变及毒性的削减

我国开采原油的稠油比重大、胶质含量高、环境风险突出,亟需解决石油污染土壤中胶质组分的解毒问题.由于胶质结构复杂、难以降解,所以对胶质结构变化的研究较少,其降解率也并不足以说明胶质污染土壤的修复效果,因此本文着重分析了修复过程中胶质结构与毒性的变化,为污染土壤修复体系提供重要指标.本文从辽河油田原油中提取胶质配制污染土,并加入构建的混合菌群.设计微生物修复(Bio)、电动-微生物修复(EK+Bio1)、电动-微生物补充营养修复(EK+Bio2)及间断电动-微生物修复(EK+Bio3)共4种处理.结果表明,胶质平均降解率EK+Bio2EK+Bio3EK+Bio1Bio,降解率最高为9.67%,为Bio处理的3.05倍(3.15%).元素分析结果表明,修复前后胶质平均化学式为C_(106)H_(157)N、C_(96)H_(174)N,碳氢比降低,不饱和度降低.光谱分析与~1H-核磁共振结果表明,修复后胶质碳链变短,芳香环、羧基与酚类结构数量减少.根据B-L法计算胶质芳碳率(f_A)由0.28减少到0.11,可推测胶质的结构模型.MicroResp~(TM)与小麦种子发芽实验结果表明,修复后土壤中微生物活性增强,小麦种子发芽率大大提高,说明结构的变化使胶质毒性降低.因此,电动-微生物修复使胶质结构发生变化,并在一定程度上有效削减了胶质毒性,较好的对胶质污染土壤进行了修复.

The structure variation and toxicity reduction of resin via electrokinetic-bioremediation

Heavy oil could expose high environmental risks attributed to one of the hazardous components known as resin. Researches of such contaminant is restrained due to its complicated structures and thus is hard to degrade. Since there are limited studies of the structure changes, current techniques that only implementing degradation rate of resin could not sufficiently reflect the remediation of petroleum-contaminated soil. This study focused on analyzing the changes of structure and toxicity of resin in order to provide significant index of the remediation system. Soil, obtained from Liaohe oilfield, was prepared by mixing bacterium and resin for the remediation experiments. There were four groups of treatments experiments designed for soil remediation including bioremediation (Bio), electrokinetic-bioremediation (EK+Bio1), electrokinetic-bioremediation with nutrient matters (EK+Bio2) and discontinuous electrokinetic-bioremediation (EK+Bio3). The results showed that the average degradation rate followed the order EK+Bio2 > EK+Bio3 > EK+Bio1 > Bio, among which the best degradation rate achieved by EK+Bio2 was 9.67%, which was 3.05 times higher than Bio (3.15%). Elemental analysis indicated that the average chemical formulas of resin before and after remediation were C₁₀₆H₁₅₇N, and C₉₆H₁₇₄N, respectively. The carbon hydrogen ratio, as well as the degree of unsaturation, was reduced after the treatment process. In addition, Spectral analysis and ¹H-NMR analysis showed that there were less aromatic nucleus, carboxyl and phenolic groups and carbon chains were shorter as well. B-L method could be used to calculate the aromatic carbon rate (f_A), which was reduced from 0.28 to 0.11 after remediation. Potential structure models of resin could be obtained based on the above-mentioned results. Meanwhile, combined MicroResp^TM analysis with wheat seed germination rate, the results showed that both the microbial activity and germination rate have been increased. Thus, it indicated that the change of structure has efficiently reduced the toxicity of resin. As a result, electrokinetic-bioremediation could change the structure and reduce the toxicity of resin, which was beneficial for remediation of resin-contaminated soil.