不同载体材料固定化耐低温混合菌修复PAHs污染土壤

Impacts of cold-resistant mixed strains immobilized by different carrier materials on remediation of PAHs polluted soils

低温条件下,向受多环芳烃污染的土壤投加高效耐冷混合菌(SDR4+JDR7),可提高土壤中PAHs的去除率,但菌体流失快,重复使用性差,微生物固定化技术在一定程度上可克服这些弊端。考虑到载体选择的微生物亲和性、吸附能力、被富集污染物的生物有效性3个可行性评价参数,本研究选用玉米芯(Y)、花生壳(H)、蛭石(Z)和泥炭土(N)作为供试载体,吸附固定化PAHs高效降解混合菌,观测各处理组对土壤中菲(Phe)、芘(Pyr)、苯并[a]芘(BaP)的降解,并采用Michaelis-Menton和Monod动力学模型对降解结果进行拟合。结果表明:60 d后,4种载体材料固定化菌Y-(SDR4+JDR7)、H-(SDR4+JDR7)、Z-(SDR4+JDR7)、N-(SDR4+JDR7)的降解能力优于游离菌。Z-(SDR4+JDR7)的降解效果最优,其对Phe、Pyr和BaP去除率分别为64.38%、48.71%和40.19%,其次为Y-(SDR4+JDR7),去除率分别为58.49%、45.91%和37.07%。Y-(SDR4+JDR7)对Phe的降解速率最大,为0.60 d^(-1),较游离菌高7.7%;Z-(SDR4+JDR7)对Pyr和BaP的降解速率最大,分别为0.54和0.20 d^(-1),较游离菌分别提高11.83%、10.85%。Z-(SDR4+JDR7)对高环BaP的降解半衰期最短,为86.64 d。本研究可为北方寒冷地区PAHs污染的土壤修复提供借鉴。

Removal of polycyclic aromatic hydrocarbons (PAHs)from soils can be enhanced by inoculation of cold-tolerant mixed strains (SDR4+JDR7)at low temperature.However,the inoc- ulated strains wouldget lost rapidly,being poor repeatability.Microbial immobilization technique can overcome these drawbacks to some extent.With affinity to microorganisms,adsorption abili- ty,and bioavailability of enriched contaminants as the three important factors for the selection of immobilization carriers,corn cob (Y),peanut shell (H),vermiculite (Z)and peat soil (N) were chosen as the carriers to adsorb and immobilize the mixed strains that are highly effective to degrade PAHs.Degradation of phenanthrene (Phe),pyrene (Pyr),and benzo (a)pyrene (BaP)in the contaminated soil was examined,and Michaelis-Menton and Mond kinetic models were applied to fit the degradation results.All the immobilized strains with the four carriers Y-(SDR4+JDRT),H-(SDR4+JDRT),Z-(SDR4+JDR7),N-(SDR4+JDRT))had better re- mediation abilities than the free strains after 60days.Among them,Z-(SDR4+JDR7)presented the best degradation abilities,with removals of Phe,Pyr and BaP being 64.38%,48.71%and 40.19%,respectively ;followed by Y-(SDR4+JDR7)with removals being 58.49%,45.91%and 37.07%,respectively.The degradation rate of Phe by Y-(SDR4+JDR7)was the highest,which was 0.60d ,7.7% higher than that by the free strains.Z一(SDR4+JDR7)showed the highest degradation rates of Pyr and BaP,which were 0.54 and 0.20 d^-1 ,respectively,with 11.83% and 10.85% increases compared to the corresponding free—living bacteria.Z-(SDR4+JDR7)had the shortest half—life of the high·ring BaP degradation,which was 86.64 d.Our results can provide reference for remediation of PAHs contaminated soil in northern China with cold climate.