3种氧化剂对焦化场地多环芳烃的修复效果与土著微生物的响应关系

Remediation of Three Oxidants on Polycyclic Aromatic Hydrocarbons in Coking Contaminated Soil and Its Response to Indigenous Microorganisms

为了探究化学氧化对污染土壤修复过程土著微生物生理生态功能的影响,以焦化场地多环芳烃(PAHs)污染土壤为实验对象,研究了高锰酸钾、过硫酸钠和臭氧这3种氧化剂在不同液固比条件下对PAHs的修复效果和土著微生物的响应关系.结果表明,该焦化场地土壤∑PAHs含量为679.1 mg·kg^(-1),高锰酸钾和过硫酸钠投加量为1%时,液固比为6∶1条件下∑PAHs(16种PAHs)的去除率最高,分别为96.9%和95.7%,而臭氧剂量为72 mg·min^(-1)、液固比为8∶1时∑PAHs的去除率(82.3%)最高;不同液固比条件下低环PAHs(3~4环)的去除率高于高环PAHs(5~6环),去除率最高的是菲和二氢苊;而对于高环的苯并[a]芘,仅高锰酸钾对其去除效果较优,去除率达到97.4%;微生物数量分析表明,土壤微生物数量经高锰酸钾处理后骤降,由108copies·g^(-1)降至105copies·g^(-1),而过硫酸钠和臭氧处理变化不明显,数量级未发生显著变化;微生物群落结构分析表明,污染原土中Proteobacteria占绝对优势,相对丰度为99.5%,高锰酸钾和过硫酸钠处理后微生物多样性显著增加,多种能够降解PAHs的微生物(如Ralstonia和Acinetobacter等)相对丰度大幅提高;微生物代谢功能路径分析表明,化学氧化处理增加了PAHs降解菌的相对丰度,提高了有机物代谢能力.总体而言,液固比为6∶1时高锰酸钾处理会显著改变土著微生物数量,微生物群落结构和PAHs降解微生物相对丰度.

To explore the influences of chemical oxidation on the physiological and ecological functions of indigenous microorganisms during contaminated soil remediation,three oxidants,including KMnO_(4),Na_(2)S_(2)O_(8),and O_(3),were selected to investigate their remediation effects on PAHs and the responses to indigenous microorganisms under different liquid-solid ratios,in this study.The results showed that:when the ΣPAHs concentration was 679.1 mg·kg^(-1) and the dosage of KMnO_(4) and Na_(2)S_(2)O_(8) was 1%,the removal efficiency of ΣPAHs reached up to 96.9% and 95.7% under the liquid-solid ratio of 6:1;for the O_(3) treatment,the removal efficiency of ΣPAHs was the highest(82.3%)at the O_(3) dosage and the liquid-solid ratio of 72 mg·min^(-1) and 8:1,respectively.The removal efficiency of low ring(3-4 rings)PAHs was higher than that of high ring(5-6 rings)PAHs under different liquid-solid ratios.The highest removal efficiencies were observed for phenanthrene and acenaphthene,whereas for benzo[a]pyrene,only the KMnO_(4)treatment provided an effective performance,showing the highest removal efficiency of 97.4%.The microbial quantity analysis indicated that the quantity of soil microorganisms in the soil dropped sharply after being treated with KMnO_(4),decreasing from 108 copies·g^(-1) to 105 copies·g_(-1),whereas it changed only slightly after being treated with Na_(2)S_(2)O_(8) and O_(3).The community structure analysis showed that Proteobacteria were predominant in the contaminated soil,with the relative abundance of 99.5%.The addition of KMnO4 and Na_(2)S_(2)O_(8) significantly increased the microbial diversity;in particular,the relative abundance of a variety of microorganisms(such as Ralstonia and Acinetobacter)that can degrade PAHs was remarkably increased.The analysis of microbial metabolic function pathways revealed that chemical oxidation could simultaneously increase the relative abundance of PAHs-degrading bacteria and improve the ability of organic metabolism.Overall,the KMnO_(4) treatment greatly altered the quantity of microorganisms and the structure of the microbial community and the relative abundance of PAHs-degrading microorganisms at the liquid-solid ratio of 6:1.