ABSTRACT
With continuous improvement of people's living standards, great efforts have been paid to environmental protection. Among those environmental issues, soil contamination by petroleum hydrocarbons has received widespread concerns due to the persistence and the degradation difficulty of the pollutants. Among the various remediation technologies, in-situ microbial remediation enhancement technologies have become the current hotspot because of its low cost, environmental friendliness, and in-situ availability. This review summarizes several in-situ microbial remediation technologies such as bioaugmentation, biostimulation, and integrated remediation, as well as their engineering applications, providing references for the selection of in-situ bioremediation technologies in engineering applications. Moreover, this review discusses future research directions in this area.
Subject(s)
Humans , Biodegradation, Environmental , Hydrocarbons , Petroleum , Soil , Soil Microbiology , Soil PollutantsABSTRACT
Bacteria, actinomycetes and fungi are the three major groups of soil microbes. Soil microbes play a critical role in ecological and biodegradation processes in petroleum-contaminated soils. Based on the actual situation, this study took the oil polluted soil around the abandoned oil well in Shehong County, Suining City, Sichuan Province as the test soil. First, we determined the physiochemical properties of the tested soil; then we analyzed the changes of physiochemical properties and the three major microbes in petroleum contaminated soils. The number of the three major microbes in contaminated soils was relatively fewer than uncontaminated samples, and the water content of the soil was in positive correlation with the number of microbes. Also we assessed the soil bacteria community diversity and changes therein in petroleum-contaminated soils using 454 pyrosequencing of 16S rRNA genes. No less than 23 982 valid reads and 6 123 operational taxonomic units (OTUs) were obtained from all 4 studied samples. OTU richness was relatively higher in contaminated soils than uncontaminated samples. Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Planctomycetes and Proteobacteria were the dominant phyla among all the soil samples. However, the prokaryotes community abundance of phyla was significantly different in the four samples. The most abundant OTUs associated with petroleum-contaminated soil sample were the sequences related to Acidobacteria, Actinobacteria and Proteobacteria, whereas the most abundance sequences with uncontaminated sample were those related to Actinobacteria, Bacteroidetes and Proteobacteria.
ABSTRACT
The aim of this study was to investigate the feasibility of using apple filter cake, a fruit-processing waste to enhance the bioremediation of petroleum contaminated soil. A rotating barrel system was used to study the bioconversion of the xenobiotic compound by natural occurring microbial population. The soil had been accidentally polluted with a total petroleum hydrocarbon concentration of 41,000 ppm. Although this global value was maintained during the process, microbial intervention was evidenced through transformation of the petroleum fractions. Thus, fractions that represent a risk for the environment (GRO, Gasoline Range Organics i.e., C6 to C10-12; DRO, Diesel Range Organics i.e., C8-12 to C24-26 and RRO, Residual Range Organics i.e., C25 to C35) were significantly reduced, from 2.95 percent to 1.39 percent. On the contrary, heavier weight fraction from C35 plus other organics increased in value from 1.15 percent to 3.00 percent. The noticeable diminution of low molecular weight hydrocarbons content and hence environmental risk by the process plus the improvement of the physical characteristics of the soil, are promising results with regard to future application at large scale.
O objetivo deste estudo foi investigara viabilidade de aplicação de bagaço de maçã, um resíduo do processamento de frutas, para melhorar a biorremediação de solo contaminado com petróleo. Para estudar a bioconversão de compostos xenobióticos pela população microbiana naturalmente presente empregou-se um sistema de barril rotativo. O solo havia sido acidentalmente contaminado com um total de hidrocarbonetos de petróleo na concentração de 41.000 ppm. Embora esse valor tenha se mantido durante o processo, a intervenção microbiana ficou evidenciada através da transformação de frações do petróleo. Assim, as frações de risco para o meio ambiente (GRO, Gasoline Range Organics, i.e., C6 a C10-12; DRO, Diesel Ramge Organics, i.e. C8-12 a C24-26 e RRO, Residual Range Organics, i.e. C25 a C35) foram significativamente reduzidas de 2,95 por cento para 1,39 por cento. Por outro lado, frações mais pesadas, acima de C35, e outros compostos orgânicos aumentaram de 1,15 por cento para 3,00 por cento. A diminuição notável do conteúdo de hidrocarbonetos de baixo peso molecular e conseqüentemente do risco ambiental por esse processo, além da melhoria das características físicas do solo, são resultados promissores para uma futura aplicação em grande escala.