Bioremediation Of Toluene Research Articles

Power generation and toluene bioremediation through single chamber benthic microbial fuel cell fed with sugarcane waste as a substrate

The water polluted with toluene could be treated using a membrane less single chamber benthic microbial fuel cells (SBMFCs) by using sugar cane waste as a substrate producing energy. Toluene oxidizes into intermediate benzoic acid and completely converts into non-toxic carbon dioxide. The BMFC generated a voltage of 0.530 V between 40 and 80 days when the external resistance was 1 kΩ. The highest power density and current density generated about 34.7 mW/m2 and 120 mA/m2 within 41 days. Furthermore, toluene remediation rate was 98.22% by BMFC. On the 41st day, redox curves were measured around −0.6 V (forward peak) and −0.5 V (reverse peak) while specific capacitance of 0.141 F/g. The Nyquist plot was fitted equivalent circuit from electro-impedance spectroscopy performed to measure overall internal resistance (54.81 Ω). The scanning electron micrographs showed that pores over multi-anode surface were improperly spaced, but these pores were for biofilm growth. The 16S rRNA pyro-sequencing results identified the Staphylococcus sp. and Pseudomonas sp. These results showed that BMFC could be used for the power production and the toluene remediation. In this work, sugarcane waste was used as a substrate in a multi-anode system, as well as toluene treatment and energy production with the help of SBMFC without membrane.

Bioremediation of toluene by bioaugmentation, biostimulation and natural attenuation

Contamination in subsurface environment is a serious environmental hazard. Main sources of the contamination are petrol, diesel fuel, gasoline at oil refineries, underground storage tanks, transmission pipelines and different industries. Permeable reactive barriers (PRBs), which is a promising technology to remediate groundwater in-situ, are filled with reactive materials for the removal of the contaminants present in groundwater. In this study, groundwater contaminated with toluene is treated in reactor columns by biological processes. This study was conducted to assess the impact of bioaugmentation (BA) and biostimulation (BS) on toluene degradation efficiency. After 44 days of treatment, toluene concentrations were decreased from 5 mg/l to 4.304 mg/l by the natural attenuation treatment (Reactor 2), which represents a 13.9% removal efficiency. Toluene was reduced to 0.0239 mg/l in the biostimulation and bioaugmentation treatment (Reactor 1), which represents a toluene removal efficiency of 99.5%. This study showed that the toluene removal efficiency in the combined BA and BS process was much higher than in natural attenuation (NA) process tested.

Characterization of Multi-Potential Toluene Metabolizing Bacteria Isolated from Tannery Effluents

The focus of present study was to isolate and characterize toluene metabolizing bacteria and evaluate their bioremediation potential. During present study bacteria were isolated from the tannery effluents using selective enrichment and serial dilution methods. The growth behavior, toluene removal efficiencies, biochemical and molecular characteristics and antibiotic resistance profiles of isolated bacteria were documented through standard procedures. Toluene degradation was also confirmed using GC-MS and LC-MS analysis of metabolites. Present study isolates (n = 20) showed top BLAST sequence similarity with Brevibacillus agri strain NBRC 15538 (75%), Bacillus paralicheniformis strain KJ-16 (20%) and Burkholderia lata strain 383 (5%). The rRNA gene sequences have been submitted to GeneBank. All present study isolates exhibited remarkable toluene removal potential and most of these were slow-growing. Biochemical characterization indicated bacteria positive for alkaline phosphatases (100%), D-glucosaminidase (35%), naphthylaminopeptidase (15%), esculinase (65%), mannitol (75%), sorbitol (95%) and inulin (90%) fermentation. Biochemical profile suggests the use of isolated bacteria for future exploitation in several fields like toluene bioremediation, ethanol production, biomass hydrolysis, biosensors, biofertilizers, as a marker for milk pasteurization in dairy industries.

Application of encapsulated magnesium peroxide (MgO2) nanoparticles in permeable reactive barrier (PRB) for naphthalene and toluene bioremediation from groundwater

One of the challenges in the petroleum hydrocarbon contaminated groundwater remediation by oxygen releasing compounds (ORCs) is to identify the remediation mechanism and determine the impact of ORCs on the environment and the intrinsic groundwater microorganisms. In this research, the application of encapsulated magnesium peroxide (MgO2) nanoparticles in the permeable reactive barrier (PRB) for bioremediation of the groundwater contaminated by toluene and naphthalene was studied in the continuous flow sand-packed plexiglass columns within 50 d experiments. For the biodiversity studies, next generation sequencing (NGS) of the 16S rRNA gene was applied. The results showed that naphthalene was metabolized (within 20 days) faster than toluene (after 30 days) by microorganisms of the aqueous phase. By comparing the contaminant removal in the biotic (which resulted in the complete contaminant removal) and abiotic (around 32% removal for naphthalene and 36% for toluene after 50 d) conditions, the significant role of microorganisms on the decontamination process was proved. Furthermore, the attached microbial communities on the porous media were visualized by scanning electron microscopy (SEM). Microbial community structure analysis by NGS technique revealed that the microbial species which were able to degrade toluene and naphthalene such as P. putida and P. mendocina respectively were stimulated by addition of MgO2 nanoparticles. The presented study resulted in a momentous insight into the application of MgO2 nanoparticles in the hydrocarbon compounds removal from groundwater.

Toluene Biodegradation by Novel Bacteria Isolated from Polluted Soil Surrounding Car Body Repair and Spray Painting Workshops

Toluene can enter the environment due to various industrial activities. Toluene exposure may cause serious health risks to human and other living organisms. Thus, removal of toluene from the environment is exceptionally important in toluene-contaminated habitats. The aim of present study was to isolate and characterize toluene-utilizing bacteria from contaminated soil surrounding car body repair and painting workshops in Irbid industrial city, Jordan. Therefore, polluted soil samples (10 g) were transferred to flasks containing 99 ml of Stanier’s medium supplemented with 1% toluene and aerobically incubated at 30°C for 72 h. Subsequently, four morphologically different toluene-utilizing bacteria, designated as T1, T2, T3, and T4, were isolated. The cells of T1, T2 and T3 were Gram-positive, rod-shaped, aerobic, and positive for oxidase and catalase. However, the cells of T4 were Gram-negative, round-shaped, aerobic, negative for oxidase, and positive for catalase. Based on 16S rDNA sequencing data, isolates T1, T2 and T3 had high homology (97% - 98%) with Lysinibacillus boronitolerans, Bacillus subtilis and Rhodococcus pyridinivorans, respectively, whereas the isolate T4 had a homology of 89% with Acinetobacter schindleri, and could represent a distinct lineage within the genus Acinetobacter. The generated 16S rDNA sequences were deposited in GenBank database. After testing different physicochemical conditions, the isolates appeared to grow best at 1% toluene, 30°C and pH 6.8, with the generation times ranged between 8 - 11 h. In conclusion, we reported for the first time the identification of four novel soil bacterial species with the capacity to utilize toluene as sole source of carbon and energy from soil sites surrounding car painting workshops. The beneficial effect of the four isolates in the bioremediation of toluene from toluene polluted soil areas must be examined under in situ and ex situ conditions.

Nitric Oxide Emissions as a Surrogate Indicator of Toluene Contaminated Soil

Emissions of nitric oxide (NO) as a surrogate indicator of toluene bioremediation from toluene-contaminated soil were measured to correlate NO and toluene contamination relationships. The goal of this study is to obtain a better understanding of the relationships between NO emissions and toluene contamination, which describes the influence of the level of toluene contamination on NO emission from the soil. Laboratory experiments were performed under controlled temperature (22°C) and water-filled pore space (WFPS, 30%) conditions, with varying toluene concentrations (0, 5, 30, 45, and 60 ppm), as well as with variations in the experimental duration (1, 4, 8, and 16 h, 1, 2, 3, and 5 days, and 1 week). The relationships have been analyzed by the comparison of experimental measurements coming from analysis of variance (ANOVA) statistical analysis, referring to toluene concentrations (0, 5, 30, 45, and 60 ppm). NO emissions were positively and significantly correlated (p < 0.01) with the level of toluene conc...

Bioremediation of Toluene and Naphthalene: development and Validation of a GC‐FID Method for Their Monitoring

Bioremediation of toluene and naphthalene in liquid cultures of bacteria grown in the presence of these aromatic compounds as unique sources of carbon was investigated by gas chromatography (GC). For this purpose, a method based on the use of GC with flame ionization detection was developed and validated. Validation was carried out in terms of limit of detection (LOD), limit of quantitation (LOQ), linearity, precision and trueness. In the case of naphthalene, LOD and LOQ values of 0.43 and 0.72 mg kg(-1) were achieved. Linearity was established over one order of magnitude in the range of interest, i.e. 10-100 mg kg(-1). Excellent precision was obtained both in terms of intra-day repeatability and between-day precision on two concentration levels (RSD% lower than 0.5%). A recovery of 97.9 +/- 0.2% (n=3) was calculated by addition of 640 mg kg(-1) of naphthalene to the Bushnell & Haas mineral salts basal solution containing the micro-organisms. Findings clearly showed a reduction of the naphthalene content equal to 50% and 75% after two and four weeks of contact with the micro-organisms, whereas a lower degradation was shown in the case of toluene. Finally bioremediation activity was ascribed to two different microbial populations, Bordetella Petrii and Bacillus Sphericus, which survived in the polluted medium.