Removal Of Benzo Research Articles

Removal of benzo[a]pyrene from the soil by adsorption coupled with degradation on saponin-modified bentonite immobilized crude enzymes

Bentonite is a non-metallic mineral with montmorillonite as the main component. It is an environmentally friendly mineral material with large reserves, wide distribution, and low price. Bentonite can be easily modified organically using the surfactant saponin to obtain saponin-modified bentonite (Sap-BT). This study investigates the immobilization of crude enzymes obtained from Trametes versicolor by physical adsorption with Sap-BT. Thus, saponin-modified bentonite immobilized crude enzymes (CE-Sap-BT) were developed to remove benzo[a]pyrene. Immobilization improves the stability of free enzymes. CE-Sap-BT can maintain more than 80% of activity at 45 °C and after storage for 15 d. Additionally, CE-Sap-BT exhibited a high removal rate of benzo[a]pyrene in soil, with 65.69% after 7 d in highly contaminated allotment soil and 52.90% after 6 d in actual soil contaminated with a low concentration of benzo[a]pyrene at a very low laccase dosage (0.1 U/3 g soil). The high catalytic and removal performance of CE-Sap-BT in contaminated sites showed more excellent practical application value.

The Effect of Bovine Serum Albumin on Benzo[a]pyrene Removal by Lactobacillus Strains.

The aim of this study was to investigate the influence of bovine serum albumin (BSA) on the Lactobacillus-strain-mediated removal of benzo[a]pyrene (BaP). A combination of 0.5 mg/mL of BSA with 1.0 × 1010 CFU/mL bacterial cells had a removal of 49.61% BaP for strain 121, while a combination of 0.4 mg/mL of BSA with 1.0 × 1010 CFU/mL bacterial cells had a removal of 66.09% BaP for strain ML32. The results indicated that the binding of BaP to Lactobacillus-BSA was stable. BSA maintains Lactobacillus activity and BaP removal in the gastrointestinal environment. Heat and ultrasonic treatment of BSA reduced the BaP-binding ability of Lactobacillus-BSA. With the addition of BSA, the surface properties of the two strains affected BaP binding. The Fourier-transform infrared (FTIR) data demonstrated that O-H, N-H, C=O, and P=O groups were involved in the binding of BaP to Lactobacillus-BSA. Scanning electron microscopy (SEM) results revealed that the morphology of Lactobacillus-BSA bound to BaP was maintained. The adsorption of BaP by Lactobacillus-BSA was appropriately described by the pseudo-second-order kinetic model and Freundlich isotherm model. BSA enhances the affinity between the bacterial cells and BaP.

Cooperative adsorption-degradation of benzo[a]pyrene by extracellular enzymes of white rot fungi immobilized on macroporous adsorption resin

Adsorption technology has been widely used in water purification, but its removal mechanism mainly depends on the enrichment and transformation of pollutants, and it cannot be completely degraded. Based on the adsorption properties of macroporous adsorbent resins and the biodegradation of extracellular enzymes of white rot fungi, a synergic study on the adsorption and degradation of benzo[a]pyrene in water was conducted in this paper. The results of the eight-resin screening exhibited that the resin AB-8 exhibited the best immobilization effect of enzymes and removal rate of benzo[a]pyrene. The removal of benzo[a]pyrene by immobilized enzymes and adsorption resin followed pseudo-secondary kinetics, while the degradation of benzo[a]pyrene by free enzymes followed first-order kinetics. Immobilized enzymes can achieve the adsorption-degradation of benzo[a]pyrene, its removal rate reached 92.78% after 6h, which is higher than the degradation rate of free enzymes and faster than the resin adsorption. After that, molecular docking indicated that van der Waals forces and Pi-Alkyl attributed to the binding of laccase and benzo[a]pyrene. Physical adsorption synergistic biodegradation technology is of great practical significance and theoretical value for the sustainable treatment of polluted water.

The Ability of Probiotic Lactobacillus Strains in Removal of Benzo[a]pyrene: a Response Surface Methodology Study.

In this study, the ability of various lactic acid bacteria was assessed in removing benzo[a]pyrene (BaP) from contaminated phosphate buffer saline (PBS). Response surface methodology (RSM) was performed using Box-Behnken design to investigate the effect of four independent variables including pH (5-7), incubation time (1-24h), cell density (107-109cfu/mL), and initial BaP concentration (5-15mg/kg) at three levels to evaluate in vitro removal of BaP as response. The results showed that all the tested strains were able to remove BaP from PBS and this reduction was entirely strain-specific. Bifidobacterium lactis BB-12 followed by Lactobacillus casei TD10 exhibited the lowest binding ability while the highest binding rate was related to Lactobacillus acidophilus LA-5, Lactobacillus delbrueckii subsp. bulgaricus PTCC 1737, Lactobacillus casei TD4, and Lactobacillus brevis TD3, respectively. Cyclohexane washing weakened BaP-bacteria complex, while this complex was not significantly changed by PBS washing. The results showed that BaP binding rate was influenced by pH, cell density, time, and BaP concentration in linear and quadratic manners. Moreover, there were interactions between cell density and time as well as between time and BaP concentration. The highest BaP-binding rate by L. acidophilus LA-5 was 10ppm of BaP concentration, pH = 5, cell density of 109cfu/mL, and an incubation period of 24h. It can be concluded that a range of pH, time, and microbial population is required to obtain maximum binding efficiency for BaP based on the concentration of the toxin and the species of the bacteria.

Removal of benzo [a]pyrene vapours from the air stream using the two-phase partitioning bioscrubber: an intervention study

ABSTRACT In this study, the absorption of BaP in gas phase and biodegradation in liquid phase were examined in a bioscrubber. Important operational parameters including, input concentration (mg/m3), output concentration (mg/m3), pollutant load (g/m3.h), removal efficiency (%), removal capacity (g/m3.h) and biomass value (g/l) were examined. The results of the study showed that the BaP degrading strain performed better degradation by increasing the organic phase concentration and detention time. The results showed that the highest efficiency and removal capacity of bioscrubber occurred at 30% organic phase concentration. Furthermore, by increasing the organic phase concentration, the removal efficiency and capacity of the bioscrubber increased. The results of the study also showed that the removal efficiency of bioscrubber increased by increasing the organic phase concentration from 0%–10%, by increasing the concentration of 10%–20% is gradually increased, and by increasing the organic phase percentage to 30%, the efficiency increased sharply. The results indicated that TPPB can have an acceptable efficacy in removing BaP, which increases by increasing the organic phase concentration leading to more BaP removal.

Efficiency of benthic diatom-associated bacteria in the removal of benzo(a)pyrene and fluoranthene

We investigated the efficiency of a benthic diatom-associated bacteria in removing benzo(a)pyrene (BaP) and fluoranthene (Flt). The diatom, isolated from a PAH-contaminated sediment of the Bizerte Lagoon (Tunisia), was exposed in axenic and non-axenic cultures to PAHs over 7 days. The diversity of the associated bacteria, both attached (AB) and free-living bacteria (FB), was analyzed by the 16S rRNA amplicon sequencing. The diatom, which maintained continuous growth under PAH treatments, was able to accumulate BaP and Flt, with different efficiencies between axenic and non-axenic cultures. Biodegradation, which constituted the main process for PAH elimination, was enhanced in the presence of bacteria, indicating the co-metabolic synergy of microalgae and associated bacteria in removing BaP and Flt. Diatom and bacteria showed different capacities in the degradation of BaP and Flt. Nitzschia sp. harbored bacterial communities with a distinct composition between attached and free-living bacteria. The AB fraction exhibited higher diversity and abundance relative to FB, while the FB fraction contained genera with the known ability of PAH degradation, such as Marivita, Erythrobacter, and Alcaligenes. Moreover, strains of Staphylococcus and Micrococcus, isolated from the FB community, showed the capacity to grow in the presence of crude oil. These results suggest that a “benthic Nitzschia sp.-associated hydrocarbon-degrading bacteria” consortium can be applied in the bioremediation of PAH-contaminated sites.

Removal of benzo[a]pyrene from soil in a novel permeable electroactive well system: Optimal integration of filtration, adsorption and bioelectrochemical degradation

A novel closed-circuit permeable electroactive well (CPEW) was constructed to remove benzo[a]pyrene (BaP) from soil. BaP was removed sequentially through interception, adsorption and further biodegradation on a graphite felt, which acted as a filtration layer and also a bioanode. The removal efficiency of absolute BaP amount in CPEW was 52.52 ± 4.23%, higher than 44.94 ± 2.69% in the control (open-circuit PEW, OPEW). Physical adsorption and biodegradation accounted for 66.31 ± 4.15% and 33.51 ± 1.58% of BaP removed from soil in CPEW, and 86.26 ± 5.21% and 13.57 ± 1.29% in OPEW at 50 d. Bioelectrochemical process greatly enhanced the biodegradation efficiency of absolute BaP amount from 6.13 ± 0.49% (OPEW) to 17.63 ± 1.49% (CPEW). High abundances of Gammaproteobacteria and Clostridia on the anode of CPEW could significantly enhance electrons transfer and thus improve BaP biodegradation. Moreover, Vibrionaceae (belonged to class Gammaproteobacteria) possibly played an important role in electron transfer. Based on the function predication analysis, the bioelectrochemical process could enhance the BaP biodegradation through increasing metabolic rates instead of changing metabolic pathways. Conclusively, CPEW, efficiently integrating filtration, adsorption and bioelectrochemical degradation, is a promising easy-to-implement in situ remediation technology for soil, sediment or groundwater contaminated with refractory organics.

Removal of benzo(a)pyrene in polluted aqueous solution and soil using persulfate activated by corn straw biochar

An activator, corn straw biochar, was produced and applied in persulfate-based oxidation to remove benzo(a)pyrene (BaP) in polluted aqueous solution and soil. Polluted aqueous solution remediation results showed that at pH 7, approximately 88.4% of BaP was removed by 10 mM of persulfate activated by 1.6 g/L of biochar, and degradation played a dominant role. Polluted soil remediation results demonstrated that the activated persulfate solution (at 9 g/L) by biochar (at 3 wt% of soil) can remove 93.2% of BaP. In remediation of BaP-polluted soil, increasing biochar dosage and persulfate concentration accelerated BaP degradation to some extent, while excessive biochar or persulfate inhibited the degradation of BaP probably due to the unnecessary SO4− consumption. The biochar-activated persulfate oxidation reflected a good performance in tolerating the influences of background electrolytes (such as HCO3−, Cl−, and humic acid (HA)) in soil on BaP remediation. In addition, in the removal of BaP by the oxidation systems activated by biochar, persulfate was proved as a superior oxidant compared to peroxymonosulfate and H2O2, and the removal efficiencies of BaP were 93.2%, 86.5%, and 84.4% under the same treatment condition. To sum up, the biochar-activated persulfate oxidation would be a potential application in remediation of BaP-polluted aqueous solution and soil.

Difference in the rhizosphere microbiome of Melia azedarach during removal of benzo(a)pyrene from cadmium co-contaminated soil

Benzo(a)pyrene (BaP) is a highly persistent biohazard polyaromatic hydrocarbon and often reported to be present in soils co-contaminated with heavy metals. The present study explains the rhizodegradation of BaP using bacterial consortium in the rhizosphere of Melia azedarach, along with a change in taxonomical and functional properties of the rhizosphere microbiome. The relative abundance of most dominant phylum Proteobacteria was 2% higher with BaP, while in the presence of both BaP and Cd, its abundance was 2.2% lower. Functional metagenome analysis also revealed the shifting of microbial community and functional gene abundance in the favor of xenobiotic compound degradation upon augmentation of bacterial consortium. Interestingly, upon the addition of BaP the range of functional abundance for genes of PAH degradation (0.165–0.19%), was found to be decreasing. However, augmentation of a bacterial consortium led to an increase in its abundance including genes for degradation of benzoate (0.55–0.64%), toluene (0.2–0.22%), naphthalene (0.25–0.295%) irrespective of the addition of BaP and Cd. Moreover, under greenhouse condition, the application of M. azedarach-bacterial consortium enhanced the degradation of BaP in the rhizosphere (88%) after 60 days, significantly higher than degradation in bulk soil (68.22%). The analysis also showed an increase in degradation of BaP by 15% with plant-native microbe association than in bulk soil. Therefore, the association of M. azedarach-bacterial consortium enhanced the degradation of BaP in soil along with the taxonomical and functional attributes of the rhizosphere microbiome.

Removal of benzo (a) anthracene from water using a novel UAE sludge-based activated adsorbent

Removal of benzo (a) anthracene from water using a novel UAE sludge-based activated adsorbent

Quantitative Determination and Removal of Benzo[a]pyrene Residue in Meat Products by Fluorescence and Polymeric Micelle

Benzo[a]pyrene (BaP) as a typical polycyclic aromatic hydrocarbon (PAH), is toxic and cancerogenic, and is widely present in processed foods especially in meat products that were smoked or salted. In this study, a robust and efficient method for quantitative determination and removal of BaP residue in meat product using fluorescence methods was introduced. A poly(ethylene glycol) (PEG) labeled at both ends with pyrene (Py-PEG-Py) was prepared and the polymer micelle was applied to remove BaP. The chemical structures of pyrene and BaP were similar so they tend to interact with each other. The steady-state fluorescence spectra showed that the ratios of excimer-to-monomer emission intensities (IE/IM) of the Py-PEG-Py sample remain constant when polymer concentration is below 0.25 g/L. Above this concentration, pyrene excimer is formed by both intramolecular and intermolecular interaction. The concentration indicates the critical micelle concentration (CMC) of Py-PEG-Py in aqueous environment. It was shown that a trace amount of BaP can be detected by fluorescence method. The fluorescence decays obtained at various polymer concentrations were also acquired by time-resolved fluorescence instrument. After the meat products were treated with Py-PEG-Py solution, BaP was completely encapsulated into the polymer micelles due to hydrophobic interaction between BaP and the pyrene pendants. In other words, BaP was fully dissolved into the micelles where the core of micelle was formed by pyrene stacking to create a hydrophobic domain and was completely separated from the meat products. This method is easy, swift, sensitive, and accurate. It can be applied to determine and remove any PAH residues in food.

English

Polycyclic aromatic hydrocarbons (PAHs) are recalcitrant contaminants which are routinely found in numerous environmental matrices, contributing to ecological degradation. In this study, the removal of LMW and HMW PAHs with 4- and 5-benzene rings, by Bacillus licheniformis STK 01, Bacillus subtilis STK 02 and Pseudomonas aeruginosa STK 03, was evaluated in silty soil for a period of 60 days. Subsequently, a biosurfactant produced from Beta vulgaris agrowaste was used to augment the removal of the aforementioned PAHs in mono- and co-cultures. The isolates proved to be proficient in removing the contaminants, with B. licheniformis STK01 cultures achieving the highest removal rates. Biosurfactant supplementation significantly enhanced the removal of benzo(a)pyrene- a 5-ring benzene HMW PAH. The highest removal rates achieved in biosurfactant-supplemented cultures were: 100% for phenanthrene, 95.32% for pyrene, 82.71% for benz(a)anthracene and 86.17% for benzo(a)pyrene. The kinetic data used to simulate removal rates were suitably described by first-order kinetics, with the rate constants showing that phenanthrene removal was rapid in cultures without biosurfactant (k = 0.0620 day-1) as well as with biosurfactant (k = 0.0664 day-1), while the removal rates for others followed in the order of their increasing molecular weight. The synergy of the bacterial isolates and the biosurfactant produced from B. vulgaris agrowaste could be used in environmental bioremediation of PAHs even in silty soil. Key words: Benz(a)anthracene, benzo(a)pyrene, bioremediation, biosurfactant, Beta vulgaris, polycyclic aromatic hydrocarbons.

The ability to remove the priority PAHs from water during coagulation process including risk assessment

The aim of the study was to determine extent, in which coagulation can affect to the risk reduction of human exposure to the consumption of water containing polycyclic aromatic hydrocarbons (PAHs). The paper presents results of research on the removal of priority PAHs (naphthalene, anthracene, fluoranthene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(g,h,i)perylene, and indeno(1,2,3-cd)pyrene) from water in the volumetric coagulation and sedimentation process. For analysis were chosen coagulants such as aluminum(VI)sulfate and two pre-hydrolyzed coagulants—PAX XL 19H and FLOKOR 1ASW/B. Water samples subjected to coagulation were collected from selected water treatment plant following the pre-ozonation process. Tested coagulants were dosed at optimal doses (2.8; 3.6 mg Al3+/L). Summary concentration of eight hazardous PAHs in water after pre-ozonation amounted to 60.78 ng/L. After volumetric coagulation using selected coagulants was in the range of 31.51–33.64 ng/L. The highest efficiency in the removal of 8 PAHs was obtained after application of FLOKOR 1 ASW/B (48.2%). Also in the removal of benzo(a)pyrene FLOKOR 1ASW/B was the most effective (decrease by 89.9%). The risk analysis was carried out for five hydrocarbons: benzo(a)pyrene, benzo(b)fluoranthene and benzo(k)fluoranthene, benzo(g,h,i)perylene and indeno(1,2,3-cd)pyrene.

Removal of Benzo[a]pyrene from Wastewater Using a Sequencing Anoxic/anaerobic-aerobic Membrane Bioreactor: Effect of SRT

Removal of Benzo[a]pyrene from Wastewater Using a Sequencing Anoxic/anaerobic-aerobic Membrane Bioreactor: Effect of SRT

Ozone oxidation and aerobic biodegradation with spent mushroom compost for detoxification and benzo(a)pyrene removal from contaminated soil

The combination of ozonation and spent mushroom compost (SMC)-mediated aerobic biological treatment was investigated in the removal of benzo(a)pyrene from contaminated soil. The performances of the process alone and combined were evaluated in terms of benzo(a)pyrene removal efficiency, mineralization efficiency (as total organic carbon removal), and soil residual toxicity (phytotoxicity to Lepidium Sativum and toxicity to Vibrio fischeri). In spite of the removal efficiency (35%) obtained by SMC-mediated biological process as a stand-alone treatment, the combined process showed a benzo(a)pyrene concentration reduction higher than 75%; the best removal (82%) was observed after 10min pre-ozonation treatment. In particular, ozonation improved the biodegradability of the contaminant, as confirmed by the increase of CO2 production (close to 70% compared to the control), mineralization (greater than 60%) and bacterial density (which increased by two orders of magnitude). Moreover, according to phytotoxicity tests on L. Sativum, the aerobic biological process of pre-ozonated soil decreased toxicity. According to the results achieved in the present study, ozonation pre-treatment showed an high potential to overcome the limitation of bioremediation of recalcitrant compound, but it should be carefully operated in order to maximize PAH removal efficiency as well as to minimize soil residual toxicity which can result from the formation of the oxidation intermediates.

Removal of Benzo[a]pyrene by a fungus Aspergillus sp. BAP14

A fungal strain BAP14 isolated from marine sediments of coast in Xiamen city, was found to have the ability to degrade benzo[a]pyrene (BaP), and identified as Aspergillus sp. based on 18S rRNA gene sequence. Aspergillus sp. BAP14 was able to remove about 30 and 60% of BaP with initial concentration of 10 mg l−1 in 3 and 12 days of incubation, respectively. Addition of saccharides and low molecular weight polycyclic aromatic hydrocarbons appeared to have effect on the degradation ability, in particularly the addition of lactose and naphthalene. Furthermore, we demonstrated that lipidic particles could be observed in the presence of benzo[a]pyrene based on the morphologic performance of Aspergillus sp. BAP14 through scanning electronic microscopy (SEM) and atomic force microscopy (AFM), respectively.

Treatment of Aluminum Plant Hazardous Wastes Containing Fluorides and PAH

Aluminum industry wastes are solid residues contaminated with polycyclic aromatic hydrocarbons (PAHs) and fluorides. The aluminum industry waste used in this study contained 1,129mgkg−1 of benzo(b,j,k)fluoranthene. On application of toxicity characteristic leaching procedure (TCLP), a leachate containing 448mgL−1 of fluoride ions was obtained. The decontamination of aluminum industry wastes was carried out in cycles and included a stage of flotation, followed by stabilization and neutralization. The flotation treatment in the cell containing wastes contaminated with a concentration of 15% (wv−1) in the presence of surfactant cocamydopropyl hydroxysultaine (0.25% ww−1) allowed 47 to 83% removal of benzo(b,j,k) fluoranthene. The subsequent step of lime stabilization (8% wv−1) allowed production of nonhazardous wastes. The concentration of fluoride ions resulting from the TCLP test (67mgL−1) remained lower than the permissible level (150mgL−1).

Removal of Pyrene and Benzo(a)Pyrene from Contaminated Water by Sequential and Simultaneous Ozonation and Biotreatment

The removal of pyrene and benzo(a)pyrene from contaminated water by sequential and simultaneous ozonation-bioremediation techniques was investigated. During the sequential treatment, ozonation using 0.5 or 2.5 mg/L ozone was used as a pretreatment process, whereas, during the simultaneous treatment process, ozonation of hydrocarbon-contaminated water at a predetermined duration using 0.5 mg/L ozone was made in the presence of microbial biomass. Ozonation was not beneficial for the removal of pyrene. However, despite a decreased specific biodegradation rate, ozonation improved the overall elimination of benzo(a)pyrene during both treatment processes. The overall removal of benzo(a)pyrene increased from 23 to 91% after exposure of the water to 0.5 mg/L ozone for 30 minutes during the simultaneous treatment process and further to 100% following exposure to 2.5 mg/L ozone for 60 minutes during the sequential treatment mode, demonstrating the benefits of combined ozonation-biological treatment for the removal of polycyclic aromatic hydrocarbons.

Ethanol inhibits benzo[a]pyrene-DNA adduct removal and increases 8-oxo-deoxyguanosine formation in human mammary epithelial cells

The effect of ethanol and acetaldehyde treatment on the removal of benzo[a]pyrene diol-epoxide (BPDE)-DNA adducts in the immortalized, human mammary epithelial cell line MCF-10F was examined. Treatment of cells with 15mM and 25mM ethanol resulted in significantly more BPDE-DNA adducts/unit DNA remaining at multiple time points, compared to controls. The half-life of BPDE-DNA adducts in cells exposed to both 15 and 25 mM ethanol were 11.9 and 12.3 h, respectively, compared to a half-life of 9.8 h for the control cells. In contrast, for cells exposed to acetaldehyde at doses of 2.5 and 5.0 μM no significant trend in BPDE-DNA adduct persistence occurred, compared to controls. The inhibition of adduct removal for cells treated with ethanol was not associated with any changes in cell viability due to ethanol exposure. However, BP-treated cells exposed to 25mM ethanol exhibited a significant 2-fold increase in 8-oxo-deoxyguanosine (8-oxo-deG) adducts compared to BP-treated cells alone. No significant increase in 8-oxo-deG was observed for cells treated with BP and exposed to 5.0 μM acetaldehyde. Thus, ethanol exposure of human mammary epithelial cells is associated with a decreased capacity to remove BPDE-DNA adducts. This inhibitory effect of ethanol on adduct removal in part may be related to ethanol-associated oxidative stress.

Removal of benzo(a)pyrene diol epoxide (BPDE)-DNA adducts as a measure of DNA repair capacity in lymphoblastoid cell lines from sisters discordant for breast cancer.

The mutagen sensitivity assay is one of the approaches used to investigate individual DNA repair capacity. This method is based on the premise that after in vitro treatment with a test mutagen, DNA from subjects with defective repair will be more damaged than DNA from those with an efficient repair system. However, very little is known about unmeasured processes that occur between cell treatment and final assessment of DNA damage. To develop a more precise assay, we modified the traditional mutagen sensitivity assay to also include measurement of DNA damage after culturing cells in the absence of mutagen. First, we treated apparently normal and xeroderma pigmentosum lymphoblastoid cell lines with various doses of benzo(a)pyrene diol epoxide (BPDE) and harvested cells at different time points. A polyclonal antiserum against BPDE-DNA was used to quantitate levels of adducts by immunoslot-blot and immunohistochemistry. Selected conditions included treatment with 10 microM BPDE, a 4-hr culture in mutagen-free medium, and immunohistochemical measurement of BPDE-DNA adducts. The method was then applied in a pilot study to 50 lymphoblastoid lines from sisters discordant for breast cancer. There was no significant difference between cases and controls in the level of BPDE-DNA adducts in lymphoblasts harvested immediately after BPDE treatment. However, after a 4-hr culture in mutagen-free medium, the level of adducts was significantly higher (P = 0.006) among cases than in controls. There was a two-fold increase in mean adduct removal in lines from nonaffected as compared to affected sisters (44% and 22% decrease, respectively). DNA repair capacity was predictive of case status (P = 0.04) in logistic regression analysis. This method, which can be easily applied to large numbers of samples, should be useful in studies to investigate the role of DNA repair in cancer risk.