Abstract:

Chlorobenzene is an important intermediate and an organic solvent used in the organic chemical industry. In the process of production, transportation, and illegal emissions, chlorobenzene migrates into the soil, posing a serious threat to the ecological environment, even directly entering and endangering human health through the food chain. As a significant receiving environment for chlorobenzene, the pollution status and green efficient remediation of soil have always been a hot issue in the environmental field. Microbial remediation has attracted much attention in the field of environmental remediation owing to its advantages of low energy consumption, green production, and lack of secondary pollution. However, microbial remediation is often confronted with key technical problems in the practice of contaminated soil remediation, such as poor survival ability and low degradation efficiency of bacterial strains. Biochar can be used to immobilize microorganisms for efficient degradation; however, its performance is often limited by its specific surface area, functional groups, and other factors. In this study, iron sulfate, attapulgite, and reed straw were mixed at a ratio of 1꞉2꞉10 and then pyrolyzed at a high temperature of 500 ℃ for 2 h without oxygen. Reed biochar was modified to improve its immobilization capacity for degrading microorganisms. Furthermore, the immobilization conditions of Pseudomonas aeruginosa W3 were optimized to prepare an iron-modified biochar-attapulgite carrier-immobilized bacterial agent (BFAT@W3) for the application in the remediation of contaminated soil. The results showed that, after the combined modification with the Fe₂(SO₄)₃ and attapulgite, the specific surface area (210.7 m²·g^-1) and pore volume (0.13 cm³·g^-1) of BC-Fe-ATP were higher and the functional groups were more abundant. The optimal conditions for the immobilization of microorganisms were as follows: adsorption temperature of 37 ℃, the adsorption time of 16 h, and carrier dosage of 15 mg·mL^-1. Under these conditions, the concentration of live cells immobilized on the carrier was 2.10×10⁹·g^-1. In practical soil contaminated by chlorobenzene, the removal rate of chlorobenzene was higher (83.4%), while the proportion of BFAT@W3 was 3꞉100, which was 18.6% higher than that of W3. High-throughput sequencing of 16S rRNA showed that the application of 3꞉100 BFAT@W3 effectively increased the relative abundance of Proteobacteria and Pseudomonas in the soil. Compared with the same proportion of W3, the application of 3꞉100 BFAT@W3 effectively increased the relative abundance of Proteobacteria and Pseudomonas in the soil by 41.3% and 36.7%, respectively, enhancing the competitive advantage in soil microbial communities. In this study, an iron-modified biochar-attapulgite carrier with good performance was used to immobilize efficient degrading bacterial agents, which provided technical support for the bioremediation of chlorobenzene-contaminated soil.

Key words: biochar, microorganisms, immobilized bacterial agent, chlorobenzene, bioremediation

摘要：

氯苯是有机化工行业重要的中间体和有机溶剂，经生产、运输过程泄漏以及末端违规排放而迁移至土壤，严重威胁生态环境和人体健康。氯苯对土壤的污染状况及绿色高效修复一直是环境领域的热点问题。微生物修复技术具有能耗低、绿色无二次污染等优点，但其在污染土壤中的实践往往面临菌株存活能力差、降解效率低等关键技术难题。生物炭可作为载体固定化高效降解微生物，但其性能常受到比表面积、官能团等因素制约。将硫酸铁、凹凸棒石和芦苇秸秆以1꞉2꞉10的比例均匀混合后在500 ℃条件下无氧热解2 h，对芦苇生物炭进行改性以提高其对降解微生物的固定能力。进一步优化了载体固定化铜绿假单胞菌Pseudomonas aeruginosa W3的条件，制备铁改性生物炭-凹凸棒石载体固定化菌剂（BFAT@W3），并将其应用于污染土壤修复。结果表明，经硫酸铁和凹凸棒石改性后的生物炭比表面积（210.7 m²·g^-1）和孔体积（0.13 cm³·g^-1）较高，官能团种类丰富。固定化降解微生物的最佳条件为吸附温度37 ℃、吸附时间16 h、载体投加量15 mg·mL^-1，此条件下固定的有效活细胞浓度为2.10×10⁹ cell·g^-1。在实际氯苯污染土壤中，投加比例为3꞉100的BFAT@W3材料对氯苯去除率较高（83.4%），较相同比例的W3提高了18.6%。16S rRNA高通量测序结果显示，3꞉100的BFAT@W3能有效增加土壤中变形菌门（Proteobacteria）和假单胞菌属（Pseudomonas）的相对丰度，相较于同比例的W3处理组分别提高了41.3%和36.7%，增强了降解微生物在土壤群落中的竞争优势。该研究通过制备性能良好的铁改性生物炭-凹凸棒石载体固定化高效降解菌剂，可为氯苯污染土壤的生物修复提供技术支撑。

关键词: 生物炭, 微生物, 固定化菌剂, 氯苯, 生物修复