Initial Polycyclic Aromatic Hydrocarbons Concentration Research Articles

Employing a magnetic chitosan/molybdenum disulfide nanocomposite for efficiently removing polycyclic aromatic hydrocarbons from milk samples

This study aimed to develop a highly efficient nanocomposite composed of magnetic chitosan/molybdenum disulfide (CS/MoS2/Fe3O4) for the removal of three polycyclic aromatic hydrocarbons (PAHs)—pyrene, anthracene, and phenanthrene. Novelty was introduced through the innovative synthesis procedure and the utilization of magnetic properties for enhanced adsorption capabilities. Additionally, the greenness of chitosan as a sorbent component was emphasized, highlighting its biodegradability and low environmental impact compared to traditional sorbents. Factors influencing PAH adsorption, such as nanocomposite dosage, initial PAH concentration, pH, and contact time, were systematically investigated and optimized. The results revealed that optimal removal efficiencies were attained at an initial PAH concentration of 150 mg/L, a sorbent dose of 0.045 g, pH 6.0, and a contact time of 150 min. The pseudo-second-order kinetic model exhibited superior fitting to the experimental data, indicating an equilibrium time of approximately 150 min. Moreover, the equilibrium adsorption process followed the Freundlich isotherm model, with kf and n values exceeding 7.91 mg/g and 1.20, respectively. Remarkably, the maximum absorption capacities for phenanthrene, anthracene, and pyrene on the sorbent were determined as 217 mg/g, 204 mg/g, and 222 mg/g, respectively. These findings underscore the significant potential of the CS/MoS2/Fe3O4 nanocomposite for efficiently removing PAHs from milk and other dairy products, thereby contributing to improved food safety and public health.

Efficient remediation of PAHs contaminated site soil using the novel slow-release oxidant material

The eco-friendly slow-release material for persulfate (PS) using chitosan (CS) and urea (U) composite as frame structure (CS-U@PS) was firstly used to remediate the site soil contaminated by polycyclic aromatic hydrocarbons (PAHs) from Hefei city, China. The influences of glutaraldehyde dosage and urea dosage on the slow released properties of CS-U@PS was investigated and a longer release time of 190.0 d to 591.0 d was achieved, indicating the promising tunability according to the contents of pollutants in site soil. The effects of various factors (cross-linking agent dosage, initial PAHs concentration, CS-U@PS dosage, hydrogen peroxide dosage, etc.) on the degradation of soil spiked with PAHs (80 and 8 mg·kg−1) by CS-U@PS were studied, and the degradation pathway of PAHs was speculated. According to the EPR results, urea played an important role in promoting the 1O2 generation, which was the main reactive oxidative species. Finally, the long-term remediation of the industrial site soil with total PAHs of 553.2 mg·kg−1 was performed using 50 mg·g−1soil CS-U@PS and 90.22% removal rate was obtained after nine months. Moreover, the monitoring results of soil respiration gas show that, in addition to CO2, there is no additional greenhouse gas generated in the process of soil remediation, suggesting that the remediation of site soil using CS-U@PS has an excellent application prospect.

Comparative efficiency of polycyclic aromatic hydrocarbon removal by novel graphene oxide composites prepared from conventional and green synthesis

New materials have been developed based on the pillars of green chemistry; however, few studies compare the potential of these materials with that of conventional materials. In this study, two composites based on graphene oxide and magnetic chitosan were synthesized, one by the green route (G-mCS/GO) and the other by the conventional route (C-mCS/GO), using proanthocyanidin (PAS) and glutaraldehyde as crosslinking agents, respectively. Then, they were applied as adsorbents in the removal of polycyclic aromatic hydrocarbons (PAHs) from synthetic wastewater to compare their performance. Through XRD analysis, the crystallographic properties were obtained, FT-IR analyses indicated the presence of functional groups associated with graphene oxide, chitosan and Fe3O4 particles, and the magnetization curves indicated greater saturation magnetization for G-mCS/GO. Adsorption assays were performed at 298 K for 30 min at pH 6.5, an adsorbent dosage of 0.1 mg mL−1 and an initial PAH concentration of 0.01 mmol. L−1 showed a greater adsorptive capacity of G-mCS/GO for naphthalene (0.093 mmol g−1) and anthracene (0.089 mmol g−1), with removal efficiencies of 93.55% and 89.25%, respectively. On the other hand, C-mCS/GO showed a better removal efficiency for fluoranthene (0.076 mmol g−1), 76.07%. The results obtained through the molecular simulation indicated that naphthalene molecules have greater stability than anthracene and fluoranthene, which contributes to increasing the hydrophobic and π-π interactions between the PAH molecules and the adsorbent surface, thus inducing an increase in the adsorptive capacity. The results of this study indicate that G-mCS/GO is a potential and sustainable adsorbent for PAH removal from wastewater.

Analysis of polycyclic aromatic hydrocarbons (PAHs) bioremediation by hydrocarbonoclastic degrading bacteria (Gordonia terrae)

One of the main focuses in developing bioremediation of Polycyclic Aromatic Hydrocarbons (PAHs) is to optimize the hydrocarbonoclastic degrading bacteria such as Gordonia terrae. However, the analysis of the bacteria's capability to degrade PAHs in different concentrations is sparsely explored. This study aims to evaluate the remediation of PAHs by Gordonia terrae by analyzing bacterial activity, PAH degradation, pH, BOD, and COD. The initial PAH concentrations used were 15 ppm, 30 ppm, and 45 ppm for 14 days of incubation. The results show bacterial activity gradually increases in each concentration up to 10-day incubation and decreases in up to 14-day incubation. Moreover, the total PAHs were gradually decreased to 54%, 69%, and 77% in the 15 ppm, 30 ppm, and 45 ppm of initial concentrations, respectively. The final pH values were 6 for all concentrations. At the same time, the BOD and COD values of each concentration gradually decreased until the end of the experiments. This study shows that Gordonia terrae can degrade PAHs, which was achieved optimally after 10 days of incubation. Furthermore, this study indicates that PAH degradation is influenced by bacterial activity, pH, BOD, and COD.

The potential of common duckweed (Lemna minor) in phytoremediation of phenanthrene and pyrene

The distribution of polycyclic aromatic hydrocarbons (PAHs) as a group of toxic and persistent aromatic pollutants in the environment is rapidly enhancing. These compounds have adverse impacts on the health of living organisms. Hence, in the present study, we investigated the potential of duckweed (Lemna minor) as an aquatic plant species for uptake, accumulation, and biodegradation of phenanthrene and pyrene under controlled conditions. L. minor plants were treated with 10 and 20 mg L-1 concentrations of phenanthrene and pyrene at the experimental duration of ten days. According to the results obtained, the toxicity of phenanthrene and pyrene contaminants on L. minor was influenced by the different initial PAHs concentrations. An increase in phenanthrene and pyrene concentration significantly decreased all studied growth parameters such as fresh weight, dry weight, and RFN and also photosynthetic pigment contents of the plant. Phenanthrene and pyrene concentrations were measured using high-performance liquid chromatography (HPLC) technique after 10 days of exposure to the PAHs. The results revealed that L. minor species could bioaccumulate effectively both typical PAHs. Furthermore, the gas chromatography-mass spectroscopy (GC/MS) technique explained the biological degradation of phenanthrene and pyrene by L. minor in the present research, and accordingly, several intermediate by-products were identified.

Utilization of activated carbon derived from waste plastic for decontamination of polycyclic aromatic hydrocarbons laden wastewater.

Serious environmental deterioration caused by synthetic waste plastics, and the pollution of freshwater resources are the most alarming and marked challenges of the 21st century. Therefore, immense scientific efforts are being made towards the management of waste plastics and treatment of polluted water. The current study reports on the utilization of waste polyethylene terephthalate (wPET) and waste polystyrene (wPS) for fabrication of activated carbon (AC) and its application for the removal of hazardous polycyclic aromatic hydrocarbons (PAHs) pollutants from water. AC was prepared from wPET and wPS by carbonization under a N2 atmosphere followed by chemical activation with 1 M KOH and 1 M HCl. The AC was characterized by scanning electron microscopy, surface area analysis, and Fourier transform infrared spectroscopy. Adsorption of PAHs from aqueous solutions through AC was examined by batch adsorption tests. The optimum parameters for maximum adsorption of PAHs were found to be: initial PAHs concentration 40 ppm, 2 h contact time, pH 3, 5, and 7, 50 °C temperature and adsorbent dose of 0.8 g. Kinetic and isotherm models were applied to evaluate the adsorbent capacity for PAHs adsorption. The kinetic study shows that the adsorption of these PAHs onto AC follows pseudo-second-order kinetics. The experimental results demonstrated that the Langmuir isotherm model best fitted the data. The thermodynamic factors calculated such as entropy change (ΔS°), enthalpy change (ΔS°) and free energy change (ΔG°) show that the adsorption process is non-spontaneous and endothermic in nature. Results were also compared with the efficiencies of some commercial adsorbents used in practice. This examination revealed that the novel plastic-derived AC possesses a great potential for elimination and recovery of PAH elimination from industrial wastewater.

Laboratory evaluation of PAHs removal by multi-functional green pervious concrete (MGPC) pavement

Stormwater runoff-induced polycyclic aromatic hydrocarbons (PAHs) contaminants increasingly endanger the groundwater reserve and ecosystems due to the extensive coverage of impervious pavements in urban surroundings. The multi-functional green pervious concrete (MGPC) pavement, a type of organoclay modified pervious concrete pavement, is proved to be an innovative and effective stormwater management method as well as an environmental technology for controlling the runoff both in quantity and quality. To further study the field applicability of the MGPC pavement, extensive experiments should be conducted by considering multiple variables that represent different scenarios, such as rainfall intensity, traffic flow, and traffic loads, stability, and reusability. This study conducts a laboratory-scale investigation of MGPC pavement performance on PAHs removal by varying a series of PAH initial concentrations, flow rate, and contamination cycles. The results indicated that lower initial PAHs concentration and slower flow rate promoted the PAHs removal efficiency, and the MGPC pavement still kept considerable PAHs adsorption capacity after 50 contamination cycles. The results provide important references in evaluating and designing the MGPC pavement as a stormwater management method with attenuating the runoff-induced PAHs contamination.

Flux of Polynuclear Aromatic Compounds (PAHs) from the Atmosphere and from Reindeer/Bird Feces to Arctic Soils in Ny-Ålesund (Svalbard).

Atmospheric, soil, and feces samples were collected in Ny-Ålesund during July 2015. The concentrations, distributions, congener profiles, and contaminant migration levels were analyzed for 16 polycyclic aromatic hydrocarbons (PAHs) identified by the United States Environmental Protection Agency (US EPA) as priority contaminants (16 PAHs). Mean concentrations in the gas and particle phases were 37.8ngm-3 and 2.9ngm-3, respectively, and mean concentrations in soil and reindeer/bird feces were 329.1ngg-1 and 720.7ngg-1, respectively, on a dry weight (d.w.) basis. In more than three phases, naphthalene and phenanthrene dominated the concentrations of the 16 total PAHs (Σ16PAH) and the concentration of PAHs in the gas phase was much higher than in the particle phase. The main sources of local PAHs may be coal combustion and air-surface exchange. There was a volatilization tendency from soil to air for 2-4 ring PAHs, and exchange fluxes were ~ 105 times greater than the deposition fluxes of 5-6 ring PAHs. The underground migration of PAHs was investigated in Ny-Ålesund; the results showed flux values of ~ 0.07% from the initial PAH concentrations.

Application of cold-adaptive Pseudomonas sp. SDR4 and Mortierella alpina JDR7 co-immobilized on maize cob in remediating PAH-contaminated freeze-thawed soil

There are large areas of contaminated soils with low- and medium-concentration of polycyclic aromatic hydrocarbons (PAHs) in the coldest regions of the earth, potentially threatening ecological safety and human health. Using maize cobs (MC) as the carrier, two cold-adaptive PAHs-degrading microorganisms, bacterial (Pseudomonas sp., SDR4) and fungal (Mortierella alpine, JDR7) strains were co-immobilized. The degradation characteristics of phenanthrene (Phe), pyrene (Pyr) and benzo[a]pyrene (BaP) in freeze-thawed soil by both co-immobilized and free microorganism were studied. The removal rate of Phe, Pyr and BaP using the co-immobilized fungal-bacterial consortium within 60 d was 59.2±3.7%, 46.6±3.3%, and 36.8±2.7%, respectively, which was obviously higher than that of free fungal-bacterial consortium in the same time. Ten percent (w/w) was the optimal amount of inoculum for PAH degradation in the co-immobilized fungal-bacterial consortium. Under low-temperature conditions, when the initial concentration of PAH was between 10-100 mg•kg−1, the immobilized cold-adaptive fungal-bacterial consortium displayed the desired degradation of PAHs. The scanning electronic microscope (SEM) observation and mass transmission showed that the microstructure of co-immobilized mixed system was beneficial to the growth of SDR4 and JDR7 at low temperature. These results imply that the cold-adaptive fungal-bacterial consortium, co-immobilized on MC, has the potential for application in remediating PAH contaminated soil under the freeze-thawing environment.

Catabolic enzyme activities during biodegradation of three-ring PAHs by novel DTU-1Y and DTU-7P strains isolated from petroleum-contaminated soil.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants having health hazards. PAH-utilizing bacterial strains were isolated from petroleum-contaminated soil from siding area, Bijwasan supply location of BPCL, Delhi, India. Bacterial strains with different morphology were isolated and acclimatized to a mixture of low molecular weight PAH compounds in the concentration range of 50-10,000mg/L. Two bacterial strains surviving at 10,000mg/L PAH concentration were identified as Kocuria flava and Rhodococcus pyridinivorans, based on 16S rRNA gene sequencing and phylogenetic analysis over MEGA X, are reported for the first time for PAH degradation. The strain K. flava could degrade phenanthrene, anthracene, and fluorene with efficiency of 55.13%, 59.01%, and 63.46%, whereas R. pyridinivorans exhibited 62.03%, 64.99%, and 66.79% degradation for respective PAHs at initial PAH concentration of 10mg/L. Slightly lower degradation of phenanthrene could be attributed to its more stable chemical structure. The consortium of both the strains degraded 61.32%, 64.72%, and 66.64%, of 10mg/L of phenanthrene, anthracene, and fluorene, respectively, in 15days of incubation period indicating no synergistic or antagonistic effect towards degradation. Catechol 2,3-dioxygenase (C23O), dehydrogenase and peroxidase enzyme activities during PAH degradation coincided with degradation of PAHs, thus highlighting the role of these enzymes in catabolising three-ring PAHs. This is the first investigation confirming the participation of C23O, dehydrogenase and peroxidases enzyme profiles throughout the period of degradation. The study concludes that these strains can play significant role in microbial remediation of PAH-contaminated environment.

Establishing the Order of Importance Factor Based on Optimization of Conditions in PAHs Biodegradation

In environmental study, optimization of different factors is crucial to obtain high removal of specific pollutants. The sequence of important factors that were considered in optimization studies is less concerned, and this part is crucial before proceeding to full-scale bioremediation study. This study focuses on bioremediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soil with the potential bacteria, Corynebacterium urealyticum which is isolated from municipal sludge. The bacterial strain has evaluated the effectiveness of PAHs degradation at various factors on soil pH, soil temperature, initial PAHs concentration, initial bacteria number, and heavy metals concentration. The optimum condition for phenanthrene biodegradation was pH 7, 30 °C, 500 mg/kg of phenanthrene concentration, 109 cells/g soil, and without the addition of Zn. In establishing the ranking, we attempt to use a simple method based on the analysis of p values. Based on the analysis of degradation rates, the initial phenanthrene concentration shows the lowest p value, which means that it shows the highest ranking; the most significant factor to achieve highest degradation. In vice versa, the soil pH shows the highest ranking based on the analysis of bacteria growth rates, which is a very limited study that focuses on growth rates in the optimization study. The establishment of these rankings may reduce time, energy and cost in pilot or field study and at the same time achieve highest degradation in bioremediation work. Thus, it is highly recommended to develop the ranking before proceeding to design work in pilot and field study.

Determination of suitable TPH remediation approach via MANOVA and inferential statistics assessment

AbstractSoil contamination resulting from petroleum hydrocarbon contaminants poses a fairly substantial hazard to human health and the environment. Phytoremediation, land farming, and chemico–biological stabilization were used to treat total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs) at a crude oil polluted soil site in Nigeria. A field pilot study was conducted by preparing nine cells with subcells attached to each serving as a control with an overall area of 1.53 m2. A complete block design method was used for the study. The prepared soil sample cells were divided into three groups with each group having approximately 300 kg of soil and delineated as low, medium, and high test plots. The low samples were spiked with 6.1 kg of crude oil, the medium samples were spiked with 12.2 kg of crudeoil, and the high samples were spiked with 18.3 kg of crude oil. Each row containing three cells with low, medium, and high concentrations were treated separately using the three treatment methods. The ratio of the soil sample to the organic amendment for the treatments was 2:1. The results showed over 90% degradation in the initial concentration of TPH and PAHs across different contaminant levels except in the control subcells where only 30% of degradation was recorded. Multivariate analysis of variance was employed to assess the significant difference in each treatment group while inferential statistics using a mean performance plot was used to ascertain the optimum treatment method. Land farming, chemico–biological stabilization, and phytoremediation ranked 1, 2, and 3, respectively. In conclusion, the three treatment methods employed all degraded the contaminants (TPH and PAHs) with land farming emerging as the best method.

Bioremediation of PAH-contaminated shooting range soil using integrated approaches

Serious contamination of polycyclic aromatic hydrocarbons (PAHs) occurs at outdoor shooting ranges due to the accumulation of clay target fragments containing coal tar or petroleum pitch. These contaminated sites are characterized with high-molecular-weight PAHs that are low in bioavailability and recalcitrant to bioremediation. We evaluated the effectiveness of different remediation strategies, used individually or in combinations, to decontaminate PAHs in a shooting range soil. The treatments included vegetation with bermudagrass [Cynodon dactylon (L.) Pers] or switchgrass [Panicum virgatum]), bioaugmentation of Mycobacterium vanbaalenii PYR-1, and addition of surfactants (Brij-35, rhamnolipid biosurfactant, or Brij-35/sodium dodecyl sulfate mixture). The initial total PAH concentration in the shooting range soil was 373 mg/kg and consisted of primarily high-molecular-weight PAHs (84%). Planting of bermudagrass and switchgrass resulted in 36% and 27% ∑16PAH reduction compared to the non-vegetated control, respectively. Bermudagrass enhanced soil dehydrogenase activity and both vegetation treatments also increased polyphenol oxidase activity. Bioaugmentation of M. vanbaalenii PYR-1 had a significant effect only on the dissipation of high-molecular-weight PAHs, leading to a 15% decrease (∑10PAH) compared to the control. In the non-vegetated soil, Brij-35/sodium dodecyl sulfate mixture increased PAH degradation compared to the no surfactant control. The increased PAH biodegradation in the vegetated and bioaugmented treatments improved lettuce [Lactuca sativa] seed germination, suggesting reduced toxicity in the treated soils. Phytoremediation using bermudagrass or switchgrass with bioaugmentation of M. vanbaalenii PYR-1 was an effective in situ remediation option for shooting range soils with heavy PAH contamination.

Dissipation and sorption processes of polycyclic aromatic hydrocarbons (PAHs) to organic matter in soils amended by exogenous rich-carbon material

PurposeThe aim of the research was to assess the effect of biochar addition on aging, degradation, and sorption processes of polycyclic aromatic hydrocarbons (PAHs) to soil organic matter. The study was carried out as a sorption experiment in strictly controlled water and air conditions, which allowed for the accurate observation and prediction of PAH behavior in soils.Materials and methodsFour soils were fortified with a PAH mixture (Fluorene-Flu, Anthracene-Ant, Phenanthrene-Phe, Pyrene-Pyr, Chrysene-Chry) at 20 mg kg−1 of single-compound concentration level. The experiment was carried out in two trials: soils + 5PAHs amended with biochar and soil + 5PAHs without biochar addition with incubation times of 0, 1, 3, 6, and 9 months. After each interval time, the extractable (E-SOM) and stable organic matter (S-SOM) were measured as well as PAHs determined in two forms: total concentration (PAH-tot) and residual concentration (PAH-rest) after E-SOM extraction. The PAH loss and half-life times were estimated according to pseudo first-order kinetics equation.Results and discussionThe amounts of PAH-tot in the soils without biochar decreased by an average of 92%, while in soil with biochar, this was 41% after 9 months of aging. The amount of PAHs-rest bounded with S-SOM after 9 months of incubation varied from 0.9 to 3.5% and 0.2 to 1.3% of the initial PAH concentration, respectively, for soils non-induced and induced by biochar. In soils without biochar, Flu, Ant, Phe, and Pyr exhibited similar T1/2 (43–59 days), but Chry was characterized by a much higher and broader T1/2 than other hydrocarbons (67–280 days). Biochar addition to the soils significantly influenced the half-life changes for all PAHs. The highest changes were noted for Phe (14-fold increase), and the lowest was for Flu (7-fold increase).ConclusionsThe addition of exogenous-rich carbon material such as biochar to the soil significantly changes the behavior and sorption potential of PAHs in the soil. Soils enriched with biochar are characterized by a higher persistence of PAHs, longer aging time, and lower affinity for sorption by native organic matter structures. Soils freshly polluted by PAH are mainly sorbed by E-SOM, which significantly increases their accessibility and reduces formation of bound-residues in the soil.

Adsorption of organic compounds on mesoporous material from rice husk ash (RHA)

The MCM-41 (TEOS) and MCM-41 (RHA) were synthesized from tetraethyl orthosilicate (TEOS) and rice husk ash (RHA), respectively. The mesoporous materials were used for the removal of the naphthalene (Nap), benzo[b]fluoranthene (B[b]F), benzo[k]fluoranthene (B[k]F), and benzo[a]pyrene (B[a]P) organic compounds from aqueous media. Polycyclic aromatic hydrocarbons (PAHs) are released into the aquatic environments via petroleum spill, industrial discharge, the combustion of fossil fuels, automobile exhaust, and nonpoint sources, such as atmospheric deposition and urban runoff. These compounds can be a threat to environment and humans, since they are recalcitrant, toxic, carcinogenic, and/or mutagenic pollutants. The mesoporous silicas were characterized by FTIR, TGA, SAXS, SEM, and N2 adsorption/desorption analyses. Removal processes were conducted to evaluate the initial PAHs concentrations and individual adsorption in comparison with the mixture of same, as well as adsorbent amount, solution pH, contact time, and temperature. The nanostructured materials exhibited the textural and structural properties typical of mesoporous materials. The qe values found in the kinetic equilibrium for the PAHs mixture followed the same increasing order for the two mesoporous materials: Nap < B[a]P < B[k]F < B[b]F, with removal percentages of 67.71, 94.30, 95.30, and 98.04% for MCM-41 (TEOS) and 79.94, 94.34, 95.32, and 98.25% for MCM-41 (RHA), respectively.

Adsorptive removal of polycyclic aromatic hydrocarbons by detritus of green tide algae deposited in coastal sediment

Rare information is available on the adsorptive removal of polycyclic aromatic hydrocarbons (PAHs) in the presence of algal detritus deposited in the coastal sediment during the outbreak of the green tide. The adsorptive removal of typical PAHs by Ulva prolifera (U. prolifera) detritus was firstly investigated since the algal detritus was of great importance for the biogeochemical cycle of coastal contaminants. The results showed that equilibrium adsorptive capacities of naphthalene, phenanthrene and benzo[a] pyrene on the U. prolifera detritus were 1.27, 1.97, and 2.49 mg kg−1, respectively, at the initial concentration of 10 μg L−1. The in situ monitoring using laser confocal scanning microscopy confirmed the adsorptive removal of PAHs by U. prolifera detritus. The adsorption of these PAHs was highly pH-dependent. The increase in salinity led to the increase in naphthalene removal rate, while the salinity showed scarce influence on the removal of phenanthrene and benzo[a] pyrene. There was a good linear relationship (R2 ≥ 0.9892) between the removal efficiency of PAHs and the initial concentration of PAHs. Slow desorption kinetics and low desorption rate (<16%) indicated that the adsorptive removal of PAHs could be benign to the environment. These findings demonstrated that the occurrence of green tide could provide a new natural remediation approach for contamination of PAHs through the adsorptive removal by the detritus of green tidal algae deposited in the coastal sediment.

In vitro removal of polycyclic aromatic hydrocarbons by lactic acid bacteria.

The current study aimed to investigate the ability of lactic acid bacteria (LABs) in removing four polycyclic aromatic hydrocarbons (PAHs) namely, benzo(a)pyrene (BaP), benz(a)anthracene (BaA), chrysene (Chr) and benzo(b)fluoranthene (BbF) from contaminated phosphate buffer saline (PBS). The effect of initial PAH concentrations (5, 10, 15, 20μgml-1 ), bacterial population (107 , 108 , 109 , 1010 CFU per ml) and pH (3, 5, 7) was studied to evaluate bacterial binding ability. All the tested bacteria could remove BaA, Chr, BbF and BaP from phosphate buffer solution and in almost all assays, removing of PAHs was as follows: BaP>Chr>BaA>BaF. Bifidobacterium lactis BB-12 had the lowest binding rate for all four PAHs, while the highest binding ability was related to Lactobacillus acidophilus LA-5. Moreover, cell viability was not required for the binding ability and even acid-treated, heat-treated and ultrasonic-treated bacterial cells showed more binding ability. The results showed that the bacteria-PAH complex was irreversible after washing with PBS. The removal of PAHs was significantly related to pH of media, strains of bacteria, type and concentration of PAHs SIGNIFICANCE AND IMPACT OF THE STUDY: This study has been focused on the reduction of polycyclic aromatic hydrocarbons using LABs and probiotics. Our results showed that not only live strains but also inactivated tested strains are able to remove PAHs from aqueous media, presenting new methods to diminish the amount of these contaminants in foods. Furthermore, the results of this study can be used in future research on evaluating the effects of oral administration of probiotic supplements and even dead probiotic strains on reducing PAHs in humans.

Dissipation of polycyclic aromatic hydrocarbons (PAHs) in soil amended with sewage sludge and sludge compost

In this study, greenhouse experiments were conducted under the condition of different amendment ratios and planting tall fescue (Festuca arundinacea). The amendment ratios of sewage sludge or sludge compost to soil were of 0, 10, 25, and 50% (w/w). The removal rates of PAH, catalase, and dehydrogenase activities of amended soil and accumulation of PAHs by vegetation were detected to investigate the differences of PAH dissipation in sludge-amended and compost-amended soils. The initial PAH concentrations in three amended soils increased with the more addition of sludge or compost. After 126-day experiment, maximum PAH removal rates were observed in sludge-amended and compost-amended soils with PAH concentration of about 200μgkg-1. And the removal of PAHs showed better efficiencies in compost soil rather than in sludge soil. The more catalase activity and dehydrogenase activity of soil were obtained, respectively, in sludge soil and compost soil. The results indicated that the mechanism of PAH dissipation in two types of amended soils were different. The abundant amount of microorganism dominated PAH dissipation in sludge soils, and PAHs dissipated mainly caused of intense activity of microorganism in compost soils. In addition, PAH accumulation in tall fescue suggested that the transference approach of PAHs was from soil to the roots, and then accumulated in the shoots of tall fescue. It was prone to store up more PAHs in vegetation in the condition of high molar weight of PAHs, more biomass of vegetation, and heavy PAH concentration in soil.

Degradation of polycyclic aromatic hydrocarbons (PAHs) during Sphagnum litters decay.

The dynamics of polycyclic aromatic hydrocarbon (PAH) degradation in Sphagnum litters and the decomposition of the litters were investigated. PAH concentration decreased to approximately half of the initial concentration as Sphagnum litters decayed. The initial PAH concentration was 489.2 ± 72.2ngg-1, and the concentration after 120days of incubation was 233.0 ± 5.8ngg-1. The different PAH compositions changed concentrations at different times. The low-molecular-weight (LMW) and high-molecular-weight (HMW) PAHs started to be degraded after incubation and after 40days of incubation, respectively. PAH concentrations in the Sphagnum litters correlated with the total organic carbon (TOC) content (p < 0.05), indicating that PAHs were associated with the TOC of the Sphagnum litters and were degraded as organic matter decayed. The positive relationship between LMW PAH concentration and the soluble carbohydrate content (p < 0.05) indicated that LMW PAHs and the readily decomposed organic carbon fractions were cometabolized, or that LMW PAHs were mainly absorbed by soluble carbohydrate. The weak negative correlation between fulvic acid (FA) and PAH concentrations (p < 0.1) indicated that FA may enhance PAH degradation. Redundancy analysis suggested that the contents of both soluble carbohydrate and cellulose significantly affected the changes in PAH concentrations (p < 0.05), and that FA content and C/N ratios may also contribute to the changes in PAH concentrations (p < 0.1). However, the polyphenol that was related to microbial activities was not associated with changes in PAH concentrations. These results suggested that litter quality is more important than microbial activities in PAH degradation in Sphagnum litters.

Removal of pyrene and benzo(a)pyrene micropollutant from water via adsorption by green synthesized iron oxide nanoparticles

Polycyclic aromatic hydrocarbons (PAHs) in water are classified as organic micropollutants, which are carcinogenic even in very low concentration (ppb). In this study the green synthesized iron oxide nanoparticles (IONPs) were green synthesized at room temperature by using pomegranate peel extract. The green synthesized IONPs were used for adsorbing benzo(a)pyrene and pyrene (PAHs) from water. Factors affecting the adsorption were investigated. These factors are: nanoparticles dose, pH, temperature, and initial concentration of PAHs. The overall results showed that the maximum adsorption capacities of IONPs towards pyrene and benzo(a)pyrene were 2.8 and 0.029 mg g−1, respectively. The thermodynamic study indicated an exothermic adsorption process of pyrene and benzo(a)pyrene. The kinetic and isotherm studies were carried out. The obtained data revealed that the adsorption process follows a pseudo-second order mechanism and obeys Langmuir isotherm model. In addition, the IONPs proved to be a potential candidate for the adsorption of pyrene and benzo(a)pyrene even after five cycles of use and regeneration. The investigation was extended using semi-pilot plant to remove the studied PAHs from artificially contaminated water. The results showed that the IONPs was capable to remove the pyrene and benzo (a) pyrene at the rate of 98.5 and 99%, respectively. It also can be used as disinfectant.