Bioremediation of polycyclic aromatic hydrocarbons: current knowledge and future directions

Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds that have accumulated in the natural environment mainly as a result of anthropogenic activities such as the combustion of fossil fuels. Interest has surrounded the occurrence and distribution of PAHs for many decades due to their potentially harmful effects to human health. This concern has prompted researchers to address ways to detoxify/remove these organic compounds from the natural environment. Bioremediation is one approach that has been used to remediate contaminated land and waters, and promotes the natural attenuation of the contaminants using the in situ microbial community of the site. This review discusses the variety of fungi and bacteria that are capable of these transformations, describes the major aerobic and anaerobic breakdown pathways, and highlights some of the bioremediation technologies that are currently available. Copyright © 2005 Society of Chemical Industry     

Biodegradation of catechol by Pseudomonas fluorescens isolated from petroleum‐impacted soil

Bioremediation strategies have been applied to clean up petroleum hydrocarbon (PHC) impacted sites. Introducing PHC degrading microorganisms (bioaugmentation) and enhancing the in‐situ nutrients availability (biostimulation) are widely used strategies. These strategies can be combined to lead to a better bioremediation performance. In this work, Pseudomonas fluorescens was isolated from a PHC impacted site. Through a 2³ factorial design plan, the effect of various combinations of nitrate, sulphate, and phosphate ions on the PHC bioremediation performance by P. fluorescens was investigated using catechol, an essential metabolic intermediate of BTEX degradation, as the sole carbon source. The maximum specific catechol degradation rate was chosen as the response to evaluate the catechol bioremediation performance. The ANOVA results indicated that the presence of nitrate ions alone lowered the maximum specific catechol degradation rate, which can be explained by the accumulation of nitrites and ammonia during the denitrification process by P. fluorescens. It was noted that dosing sulphate ions alone did not affect the bioremediation performance, which indicates P. fluorescens can grow in a sulphur‐limited environment. In contrast, the presence of sulphate and nitrate ions together can lead to a higher specific catechol degradation rate. This may be caused by the presence of sulphate that can suppress the production of nitrites. The importance of phosphate ions on catechol biodegradation was investigated. The absence of phosphate led to incomplete biodegradation. Introducing phosphate ions can accelerate catechol degradation, which can be explained by the secretion of organic acids.     

城区内河水环境的生物治理——以池州市清溪河为例

对清溪河污染的治理,可以采用一系列理化的方法,但相比之下,利用生物治理不仅操作简便,成本低廉,而且能很好的修复水生生态系统的结构,达到良性循环的效果。驳岸的植物是一道屏障,能有效阻止和减少地表污染物进入水体,水中微生物将有机态的污染物转化为无机养份被植物吸收,植物为水中的微生物提供附着表面,而草食性鱼类能抑制植物的过渡生长,最终实现生态系统的重建与修复,使河道进入可持续发展的良性循环体系。     

利用基因工程菌修复富营养化水体

以徐州市黄河故道应用基因工程菌修复富营养化水体为研究对象，对水体中富营养化指标进行了测定，并对水体中生物生长变化情况进行了观察，试验和分析了基因工程菌中的消氮细菌及沉淀细菌对水体进行生物修复的作用及其效果，指出了存在的问题，为利用生物修复技术处理天然湖泊的富营养化提供了参考数据．     

石油污染土壤生物修复与多技术联合修复策略研究进展及工程化应用

在传统石油污染土壤修复方法的基础上,综述了生物修复联合多技术修复石油污染土壤的方法、原理、研究现状及应用。并对如何更好地将生物修复与多技术相结合,提高修复效率和改善修复产物提出了展望,对采用以生物修复为核心的多技术联合修复策略在油田污染治理和生态环境恢复方面具有指导意义,以期为提高石油污染土壤修复效果提供依据。     

Remediation of phenol-contaminated soil by a bacterial consortium and Acinetobacter calcoaceticus isolated from an industrial wastewater treatment plant

Time-course performance of a phenol-degrading indigenous bacterial consortium, and of Acinetobacter calcoaceticus var. anitratus, isolated from an industrial coal wastewater treatment plant was evaluated. This bacterial consortium was able to survive in the presence of phenol concentrations as high as 1200mgL(-1) and the consortium was more fast in degrading phenol than a pure culture of the A. calcoaceticus strain. In a batch system, 86% of phenol biodegradation occurred in around 30h at pH 6.0, while at pH 3.0, 95.2% of phenol biodegradation occurred in 8h. A high phenol biodegradation (above 95%) by the mixed culture in a bioreactor was obtained in both continuous and batch systems, but when test was carried out in coke gasification wastewater, no biodegradation was observed after 10 days at pH 9-11 for both pure strain or the isolated consortium. An activated sludge with the same bacterial consortium characterized above was mixed with a textile sludge-contaminated soil with a phenol concentration of 19.48mgkg(-1). After 20 days of bioaugmentation, the remanescent phenol concentration of the sludge-soil matrix was 1.13mgkg(-1).     

Design and performance of biofilters for the removal of alkylbenzene vapors

Three identical biofilters, run under the same conditions but inoculated with different mixed cultures, were fed a mixture of toluene, ethylbenzene, and o-xylene (TEX) gases. Inert porous perlite was used as support material, in contrast to the more conventional biofiltration systems where natural supports are used. Biodegradation started in all three biofilters a few hours after inoculation, without previous adaptation of the inocula to the toxic mixture. Despite acidification of the systems to pH values below 4·5, the elimination capacities reached were fully satisfactory. The best performing biofilter, in which bacteria were dominant, showed an elimination capacity of 70 g TEX m⁻³ h⁻¹ with a near complete removal of the mixture up to an influent concentration of 1200 mg TEX m⁻³ at a gas residence time of 57 s. Most of the ingoing carbon was recovered as carbon dioxide in the outgoing gas. In the other biofilters fungi dominated and performance was slightly worse. With single substrates, the elimination capacity was higher for toluene and ethylbenzene than for the TEX mixture, whereas o-xylene removal was slowest in all cases. Also when feeding the mixture to the biofilters, o-xylene was removed most slowly.     

受污染含水层抽水——处理最优化及对地下水污染生物修复的基本认识

本文讨论了修复受污染含水层的抽水———处理技术的最优化问题,提出建立抽水———处理最优化模型时应注意的三个要素,以确定含水层修复的最佳战略。认为抽水———处理技术是一种好方法。涉及与地下水污染有关的问题,需要能够模拟在地下进行的生物修复和污染物运移的计算机模型。近年来,研发了许多数字程序来认识生物降解/生物变换过程。可是,对这种生物修复系统进行数值模拟,总是需要做出确实的计算上的努力。如果有一些恰当的解析解可作为适宜应用的筛选手段,则便于在详细研究以前进行生物修复评价。本文提出了模拟生物修复和有反应运移的解析模型的文献评论。     

分子生物学技术在土壤生物修复中的应用及展望

综述了分子生物学技术包括环境微生物群落降解基因分析、16S rRNA序列分析技术以及荧光原位杂交技术在生物修复技术中跟踪污染土壤中降解微生物行为、监测降解基因和微生物群落变化,揭示了其中的分子机制的应用现状,对各项技术应用中需要注意的问题进行了讨论并对其发展前景进行了展望。     

阴沟肠杆菌对石油烃污染物的降解特性

考察了阴沟肠杆菌E．cloacae对石油烃代表物十六烷及菲的降解特性,分析了菌在各碳源中的生长动力学曲线及各碳源的降解动力学曲线。结果表明E.cloacae在十六烷、菲、十六烷和菲的混合物这三种碳源中都能较好地生长,生长速率较高,生长过程中都有二次生长现象;E．cloacae对葡萄糖、十六烷、菲、以及十六烷和菲混合物中所含菲在1天内平均降解速率大小关系为十六烷〉葡萄糖〉菲（十六烷与菲混合）〉菲,E．cloacae对十六烷具有很强的降解能力,1天内其对十六烷的平均降解速率是其对葡萄糖的2．4倍,是对单独菲及混合菲的6200倍。最终结果表明E．cloacae是一种高效的石油烃降解菌。