Effectiveness Of Bioremediation Process Research Articles

Effectiveness of bioremediation process in hydrocarbon - contaminated soils

The present study was undertaken to evaluate the efficacy of introduced indigenousbacterial isolates for ex situ bioremediation of fuel oil contaminated soil. For this purposethree hydrocarbon-degrading indigenous bacterial isolates were screened from petroleumoil contaminated soil and repeatedly used for inoculation of fuel oil contaminated soil.The total petroleum hydrocarbons (TPH) content was determined by gravimetric method,Hydrocarbon fractions (alkanes, aromatics, asphaltenes and resins) present in TPH wereobtained by silica gel column chromatography. The study showed that some introducedbacterial isolates effectively adapted to the contaminated soil. The bioaugmentation effectwas calculated to raise the numbers of bacteria by approximately one order of magnitudefrom the indigenous population at the site. Ex situ study showed that the introducedbacterial consortium effectively adapted to the local environment of the soil at thebioremediation site.Our results indicated that disappearance of TPH from inoculated soil samples dependedon the general soil impurity, term of bacterial treatment, level of TPH contamination andindividual microorganism efficacy. With application of bacterial consortium andfertilizers, the TPH level was reduced to 60 - 66% after three months.

Quantitative detection of isotopically enriched E. coli cells by SERS.

It is clear that investigating how bacterial cells work by analysing their functional roles in microbial communities is very important in environmental, clinical and industrial microbiology. The benefits of linking genes to their respective functions include the reliable identification of the causative agents of various diseases, which would permit appropriate and timely treatment in healthcare systems. In industrial and municipal wastewater treatment and management, such knowledge may allow for the manipulation of microbial communities, such as through bioaugmentation, in order to improve the efficiency and effectiveness of bioremediation processes. Stable isotope probing coupled with identification techniques has emerged to be a potentially reliable tool for the discrimination, identification and characterization of bacteria at community and single cell levels, knowledge which can be utilized to link microbially mediated bioprocesses to phylogeny. Development of the surface-enhanced Raman scattering (SERS) technique offers an exciting alternative to the Raman and Fourier-transform infrared spectroscopic techniques in understanding the metabolic processes of microorganisms in situ. SERS employing Ag and Au nanoparticles can significantly enhance the Raman signal, making it an exciting candidate for the analysis of the cellular components of microorganisms. In this study, Escherichia coli cells were cultivated in minimal medium containing different ratios of 12C/13C glucose and/or 14N/15N ammonium chloride as the only carbon and nitrogen sources respectively, with the overall final concentrations of these substrates being constant. After growth, the E. coli cells were analyzed with SERS employing an in situ synthesis of Ag nanoparticles. This novel investigation of the SERS spectral data with multivariate chemometrics demonstrated clear clusters which could be correlated to the SERS spectral shifts of biomolecules from cells grown and hence labelled with 13C and 15N atoms. These shifts reflect the isotopic content of the bacteria and quantification of the isotope levels could be established using chemometrics based on partial least squares regression.

Microbial removal of weathered hydrocarbons by well adapted-bacteria

The effectiveness of bioremediation processes may be limited by the physical and chemical properties of the pollutant, such as availability, recalcitrance, concentration and weathering, among others. The aim of this work was to evaluate the removal of recalcitrant oil fractions (aliphatic-aromatic and asphaltenic fractions) from a weathered soil, by two bacteria adapted to a high concentration of oil hydrocarbons, isolated from a soil with a concentration of 227,000 mg of total petroleum hydrocarbons per kg soil. Kinetics of hydrocarbons removal by Bacillus coagulans and/or Serratia liquefasciens was performed in liquid culture for 168 h; hydrocarbons from soil as sole carbon and energy source (600 mg/l) were added and each of the microorganisms was inoculated for evaluation independently or as a mixed culture. The aromatic fraction was removed by B. coagulans at 330 mg/l; by S. liquefasciens at 130 mg/l; and by both microorganisms at 360 mg/l. The asphaltenic fraction was removed by B. coagulans at 23 mg/l; by S. liquefasciens at 15 mg/l; and by both microorganisms at 34 mg/l. Chromatographic analysis of the aliphatic-aromatic fraction showed the presence of branched aliphatic C6 to C26, polyaromatic substituted compounds of two and three rings, and heteroaromatic compounds of dibenzothiphene type. The compounds that were removed from the aliphatic-aromatic fraction were of all types in the range of C6 to C13. Keywords : Asphaltenes, aliphatic-aromatic fraction, weathered, biodegradation African Journal of Biotechnology Vol. 12(9), pp. 941-948

Comparison of biostimulation and bioaugmentation techniques for the remediation of used motor oil contaminated soil

This study was carried out on the bioremediation of used motor oil contaminated soil artificially contaminated to a pollutant level of 40,000ppm using biostimulation and bioaugmentation remediation techniques for 42 days. Four treatment options were investigated in wooden microcosms: Control (T1), water amended (T2), biostimulation (T3) and hybrid of biostimulation and bioaugmentation (T4). The effectiveness of bioremediation processes were monitored using the total petroleum hydrocarbon removal (TPH) and total bacterial count (TBC). T3 had the highest TPH removal rate (69.2±0.05%), followed by T4 (65.2±0.25%) and T2 (58.4±0.5%); the control (T1) had the lowest TPH removal rate (43.2±1.5%). TBC revealed that bioremediation actually took place; T4 had the highest maximum bacterial growth of 9.6E+07CFU/g, followed by T3 (7.2E+07CFU/g), T2 (1.7E+05CFU/g) and T1 (1.65E+05CFU/g). In addition, T3 had the highest metal removal rate (2.172%) and T4 had the lowest metal removal rate (0.203%).

Evaluating the biodegradation of aromatic hydrocarbons by monitoring of several functional genes

Various microbial activities determine the effectiveness of bioremediation processes. In this work, we evaluated the feasibility of gene array hybridization for monitoring the efficiency of biodegradation processes. Biodegradation of 14C-labelled naphthalene and toluene by the aromatic hydrocarbon-degrading Pseudomonas putida F1, P. putida mt-2 and P. putida G7 was followed in mixed liquid culture microcosm by a preliminary, nylon membrane-based gene array. In the beginning of the study, toluene was degraded rapidly and increased amount of toluene degradation genes was detected by the preliminary gene array developed for the study. After toluene was degraded, naphthalene mineralization started and the amount of naphthalene degradation genes increased as biodegradation proceeded. The amount of toluene degradation genes decreased towards the end of the study. The hybridization signal intensities determined by preliminary gene array were in good agreement with mineralization of naphthalene and toluene and with the amount of naphthalene dioxygenase and toluene dioxygenase genes quantified by dot blot hybridization. The clear correlation between the results obtained by the preliminary array and the biodegradation process suggests that gene array methods can be considered as a promising tool for monitoring the efficiency of biodegradation processes.

Changes in Toxicity and Mobility Resulting from Bioremediation Processes

Bioremediation is a commonly used process for the remediation of soils and sludges containing hydrocarbon compounds. The extent of chemical concentration reduction that occurs in bioremediation processes and the concentration of residual chemicals varies widely for different soils and sludges and for different processes. Along with changes in chemical concentration, measures of toxicity and chemical mobility are important information as site remediation decisions are increasingly being made within a risk-based corrective action framework. This review article presents illustrative data from studies that evaluated the effectiveness of bioremediation processes and that contained information about changes in chemical mobility and soil or sludge toxicity. The weight-of-evidence data presented indicated that, as part of the bioremediation process, there is a reduction of the apparent toxicity of the soils and sludges that were treated. In addition, remaining chemical constituents generally were less mobile. The patterns were consistent for both laboratory and field-scale bioremediation studies.