Removal Of Polycyclic Aromatic Hydrocarbons Research Articles

Removal of Polycyclic Aromatic Hydrocarbons in a Heterogeneous Fenton Like Oxidation System Using Nanoscale Zero-Valent Iron as a Catalyst

Oil and gas effluents contains highly toxic and harmful organic pollutants. Therefore, it is necessary to eliminate and/or reduced the concertation of organic pollutants to a technologically acceptable levels before their discharge into water streams. This study investigates the application of nanoscale zero-valent iron (nZVI), and hydrogen peroxide (H2O2) for removal of organic pollutants from real oily produced water. Batch studies were performed and effect of different operating parameters, including concentration of nZVI and H2O2, pH and reaction time were studied. Moreover, optimization of independent variables was performed using central composite design (CCD) in response surface methodology (RSM). The experimental set up provided maximum removal efficiencies of 89.5% and 75.3% for polycyclic aromatic hydrocarbons (PAHs) and chemical oxygen demand (COD), respectively. The optimum values of independent variables such as concentrations of nZVI, and H2O2, contact time and pH were obtained as 4.35 g/L, 1.60 g/L, 199.9 min and 2.9, respectively. Predicted PAHs and COD removal efficiencies at the optimum values of independent variables were found as 89.3% and 75.7%, respectively which are in line with the experimental values. The study indicates that application of heterogeneous Fenton like oxidation system using nZVI as a catalyst is an efficient treatment method for removal of organic pollutants from real produced water.

Assessment of European and hybrid aspen clones efficiency based on height growth and removal percentage of petroleum hydrocarbons\u2014a field trial

Soils polluted by organic or inorganic pollutants are an emerging global environmental issue due to their toxic effects. A phytoremediation experiment was conducted to evaluate the extraction potential of three European aspen clones (R2, R3, and R4) and seven hybrid aspen clones (14, 27, 34, 134, 172, 191, and 291) grown in soils polluted with hydrocarbons (includes polycyclic aromatic hydrocarbons (PAH) and total petroleum hydrocarbons (TPH)). Height growth, plant survival rates, and .hydrocarbon removal efficiencies were investigated over a 4-year period at a site in Somerharju, Luumaki Finland, to assess the remediation potential of the clones. Hydrocarbon content in the soil was determined by gas chromatography and mass spectrometry. The results revealed that hybrid aspen clones 14 and 34 and European aspen clone R3 achieved greater height growth (171, 171, and 114 cm, respectively) than the other clones in the study. Further, the greatest removals of PAH (90% at depth 10–50 cm) and (86% at depth 5–10 cm) were observed in plot G15 planted with clone R2. Furthermore, the greatest TPH removal rate at 5–10 cm depth (C22–C40, 97%; C10–C40, 96%; and C10–C21, 90%) was observed in plot 117 with clone 134. However, other clones demonstrated an ability to grow in soils with elevated levels of TPH and PAH, which indicates their tolerance to hydrocarbons and their potential capacity for phytoremediation of hydrocarbon-polluted soils. Our study suggests that European aspen and hybrid aspen clones could be used for the remediation of soils polluted with PAH and TPH.

Advances in water treatment technologies for removal of polycyclic aromatic hydrocarbons: Existing concepts, emerging trends, and future prospects.

In the last two decades, environmental experts have focused on the development of several biological, chemical, physical, and thermal methods/technologies for remediation of PAH-polluted water. Some of the findings have been applied to field-scale treatment, while others have remained as prototypes and semi-pilot studies. Existing treatment options include extraction, chemical oxidation, bioremediation, photocatalytic degradation, and adsorption (employing adsorbents such as biomass derivatives, geosorbents, zeolites, mesoporous silica, polymers, nanocomposites, and graphene-based materials). Electrokinetic remediation, advanced phytoremediation, green nanoremediation, enhanced remediation using biocatalysts, and integrated approaches are still at the developmental stage and hold great potential. Water is an essential component of the ecosystem and highly susceptible to PAH contamination due to crude oil exploration and spillage, and improper municipal and industrial waste management, yet comprehensive reviews on PAH remediation are only available for contaminated soils, despite the several treatment methods developed for the remediation of PAH-polluted water. This review seeks to provide a comprehensive overview of existing and emerging methods/technologies, in order to bridge information gaps toward ensuring a green and sustainable remedial approach for PAH-contaminated aqueous systems. PRACTITIONER POINTS: Comprehensive review of existing and emerging technologies for remediation of PAH-polluted water. Factors influencing efficiency of various methods, challenges and merits were discussed. Green nano-adsorbents, nano-oxidants and bio/phytoremediation are desirous for ecofriendly and economical PAH remediation. Adoption of an integrated approach for the efficient and sustainable remediation of PAH-contaminated water is recommended.

Removal of polycyclic aromatic hydrocarbons from aqueous media using modified clinoptilolite

Carcinogenic polycyclic aromatic hydrocarbons (PAHs) are widespread in the environment. In this study, the removal of PAHs from aqueous media was assessed using samples of clinoptilolite, a natural zeolite, pre-treated with 1 mol/L of NaCl, (Na pre-treated clinoptilolite, NC). Samples (10 g) of NC were separately modified with 5, 2, 2, and 20-mmol/L solutions of cetylpyridinium chloride (CPC), didodecyldimethyl ammonium bromide (DDAB), hexadecyltrimethylammonium bromide (HDTMA), and tetramethyl ammonium chloride (TMA) surfactants as potential cost-effective adsorbents. The kinetics, optimal sorbent dosage, and competitive effects were evaluated through batch adsorption tests using deionised water spiked with five PAHs (anthracene (50 μg/L), fluoranthene (100 μg/L), fluorene (100 μg/L), phenanthrene (100 μg/L), and pyrene (100 μg/L)). The surfactant non-modified (NC) and TMA-MC (modified clinoptilolite) exhibited PAH removal of <66% from the spiked concentration in aqueous solution, while CPC-MC, DDAB-MC, and HDTMA-MC achieved removal rates of >93% for the five PAHs after 24 h at a solid:liquid ratio of 1:100. The remaining concentrations of anthracene and fluoranthene were below 3 μg/L, and that of fluorene was <6 μg/L, lower than the water quality criteria of British Columbia, Canada, for protecting aquatic life. However, HDTMA-MC retained >83% of the fluorene. Over 80% of all PAHs were absorbed within 15 min for the CPC-MC and DDAB-MC, and the maximum adsorption was reached in <2 h. Three kinetic models were applied assuming pseudo-first-order, pseudo-second-order, and intra-particle equations, and the results were well-represented by the pseudo-second-order equation. The PAH sorption results indicated that the adsorption mechanism is based on PAH hydrophobicity, and π-π electron-donor-acceptor interaction with surfactant. CPC and DDAB with two long chain hydrocarbons had more PAH adsorption than HDTMA with one, and TMA with no long chain hydrocarbons (DDAB-MC > CPC-MC > HDTMA-MC ≫ TMA-MC > NC). With a solid:liquid ratio of 1:200, over 90%, 80%, and 70% of the anthracene, fluoranthene, and pyrene were adsorbed by the CPC-MC, DDAB-MC, and HDTMA-MC, respectively.

Ligninolytic enzyme involved in removal of high molecular weight polycyclic aromatic hydrocarbons by Fusarium strain ZH-H2.

The capacity of Fusarium sp. strain ZH-H2 to secret lignin peroxidase (LiP), laccase (Lac), and manganese peroxidase (MnP) and degrade high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) was studied. When the fungus was grown in control mineral salt medium for 4days, LiP and Lac activities were detected at 8871UL-1 and 5123UL-1, respectively. In the presence of HMW-PAHs as the sole carbon source, only LiP activity was detectable, and LiP activity had significantly reduced HMW-PAHs at day 7, with a maximum decrease of 85.9%. A strong correlation between LiP activity and HMW-PAHs removal efficiency could be fit into various models, with the highest correlation coefficients obtained for quadratic functions (P < 0.01). When a specific enzyme inhibitor was added, the ability of Fusarium to remove HMW-PAHs was reduced from 85.9 to 66.7%, depending on the inhibitor's concentration. Meanwhile, the determined activity of LiP was reduced from 11.4 to 48.6%. We conclude that in the presence of HMW-PAHs as the only carbon source to support growth, Fusarium ZH-H2 mainly produces LiP but not Lac or MnP for HMW-PAHs degradation. To our knowledge, it was the first time to propose a metabolic lignin peroxidase characterization of HMW-PAHs degradation by Fusarium sp. strains.

A review of polycyclic aromatic hydrocarbons and their substitutions in full‐scale wastewater treatment plants

AbstractWastewater treatment plants (WWTPs) become a main contributor of polycyclic aromatic hydrocarbons (PAHs) and their substitutions present in freshwater systems. This paper reviews PAHs and their substitutions in full‐scale WWTPs including their fate and behaviors, analytical techniques, biological treatments, feasibility examination, and modeling. In addition, challenges and future outlook are also highlighted. This study found that PAHs and their substitutions have been detected in WWTPs. GC‐MS and HPLC analytical methods have been found to be acceptable for the detection and analysis of PAHs and their substitutions. Although some biological treatments such as activated sludge and membrane bioreactors are capable for the treatment process, their technical, social, economic, and environmental aspects must be considered. The fate and treatability estimator (FATE) model has been used for the modeling of removal of PAHs in full‐scale WWTPs, but in some cases their shortcoming has been reported, which calls for an evaluation and modification of the model based on physicochemical processes.

Enhanced phytoremediation of PAHs and cadmium contaminated soils by a Mycobacterium

This study investigated Fire Phoenix (Festuca L.) and Echinacea purpurea (L.) Moench inoculated with a Mycobacterium strain N12 in remediation of soils contaminated with both polycyclic aromatic hydrocarbons (PAHs) and cadmium (Cd). Plant growth and PAH and Cd removal were monitored in 60, 120, and 150 days after transplanting. Results showed that Fire Phoenix plants grown in soil containing 200 mg/kg PAHs and 15 mg/kg Cd inoculated with N12 were able to remove 76.3% PAHs compared to removal of 68.3% of PAHs by the plants without N12 inoculation. On day 150, the underground biomass of Fire Phoenix plants grown in soil inoculated with N12 increased 59.40% compared to that without N12 inoculation. The enhanced removal of PAH by Fire Phoenix and N12 was related to the improved rhizosphere microbial activities. However, inoculation of N12 to E. purpurea grown soil did not significantly improve the removal of PAHs and Cd. Our results showed that phytoremediation of PAHs and Cd can be enhanced by a Mycobacterium strain N12, especially when PLFA concentrations of bacteria and fungi exceeded 60% of the initial concentrations, but the enhancement is plant species dependent.

Response of soil bacterial communities to polycyclic aromatic hydrocarbons during the phyto-microbial remediation of a contaminated soil

Rhizo-box experiments were conducted to analyze the phyto-microbial remediation potential of a grass (Lolium multiflorum L.) and a crop (Glycine max L.) combined with exogenous strain (Pseudomonas sp.) for polycyclic aromatic hydrocarbons (PAHs) contaminated soils. The dynamics of bacterial community composition, abundances of 16 S rDNA and ring hydroxylating dioxygenases (RHDα) genes, and removal of PAHs were evaluated and compared on four culture stages (days 0, 10, 20, and 30). The results showed that 8.65%–47.42% of Σ12 PAHs were removed after 30 days of cultivation. Quantitative polymerase chain reaction (qPCR) analysis indicated that treatments with soybean and ryegrass rhizosphere markedly increased the abundances of total bacteria and PAH-degraders, especially facilitated the growth of gram-negative degrading bacteria. Flavobacterium sp. and Pseudomonas sp. were the main and active strains in the control soil. However, the presence of plants and/or exogenous Pseudomonas sp. changed the soil bacterial community structure and modified the bacterial diversity of PAH-degraders. On the whole, this study showed that the high molecular weight PAHs removal efficiency of phyto-microbial remediation with ryegrass was better than those of remediation with soybean. Furthermore, the removals of PAHs strongly coincided with the abundance of PAH-degraders and bacterial community structure.

Enhancing Salix viminalis L.-mediated phytoremediation of polycyclic aromatic hydrocarbon-contaminated soil by inoculation with Crucibulum laeve (white-rot fungus).

Although plant-white-rot fungi (WRF) remediation is considered efficient in improving polycyclic aromatic hydrocarbon (PAH)-contaminated soil, the prospects for using it remain poorly known. Therefore, we evaluated whether the WRF Crucibulum laeve could improve the phytoremediation of PAH-contaminated soil by Salix viminalis L. A 60-day pot experiment was conducted to investigate the effects of C. laeve inoculation (using two inoculation treatments and a non-inoculated control) on the phytoremediation potential, growth, and antioxidant metabolism of S. viminalis cultivated in PAH-contaminated soil. The S. viminalis-C. laeve association synergistically caused the highest PAH removal rate. Under the S. viminalis-C. laeve treatment, 80% of the biological concentration and translocation factors for all tissues of S. viminalis were > 1, whereas only 20% of these factors were > 1 when S. viminalis was used alone. C. laeve inoculation remarkably enhanced phytoremediation by promoting S. viminalis-based phytoextraction of PAHs from soils. Furthermore, although C. laeve inoculation altered the antioxidant metabolism of S. viminalis by inducing oxidative stress, thereby inhibiting plant growth, the plant's hardiness enabled it to survive and grow normally for 60days after treatment. Therefore, phytoremediation using S. viminalis inoculated with C. laeve can be considered a feasible approach for the phytoremediation of PAH-contaminated soil.

Remediation of PAHs-contaminated water and sand by tropical plant (Eleocharis ochrostachys) through sub-surface flow system

Polycyclic aromatic hydrocarbons (PAHs) removal by the tropical plant, Eleocharis ochrostachys, from contaminated water and sand using sub-surface flow system (SSF) was conducted for 80 days. E. ochrostachys was exposed to various concentrations of diesel (0.5, 1, 2 and 3% v/v). Treatments with and without the plant were conducted to analyse the effect of plants in removing PAHs. A liquid–liquid extraction method was used to extract the PAHs from the wastewater. The PAH removal with plants was significantly better than without plants (p<0.05). At diesel concentrations of 0.5, 1, 2 and 3%, the PAH removal percentages with plants were 89.1, 91.3, 73.0 and 71.6% from water and 95.3, 97.2, 97 and 86.2% from the sand, respectively, while the removals without plants were only 81.8, 81.0, 63 and 63.9% from water and 93.6, 93.9, 95.7 and 81.8% from the sand, respectively. Increasing colony-forming units (CFUs) surrounding the plant roots indicated enhanced growth of rhizobacteria, which could assist the removal of pollutants. Additionally, the gravel layers had removed the total suspended solid (TSS) from 87 to 98%.

Activation of percarbonate by water treatment sludge–derived biochar for the remediation of PAH-contaminated sediments

Sludge from a groundwater treatment plant was used to prepare biochar by pyrolysis. The Fe–Mn rich biochar was used to activate percarbonate for the remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated aquatic sediments. Results showed that the sludge–derived biochar (SBC) produced at a pyrolysis temperature of 700 °C was the most effective in activating percarbonate, which exhibited significant oxidative removal of PAHs. PAHs degradation took place via a Fenton-like oxidation manners, contributed from the Fe3+/Fe2+ and Mn3+/Mn2+ redox pairs, and achieved the highest degradation efficiency of 87% at pH0 6.0. Reactions between oxygenated functional groups of biochar and H2O2 generated of O2•– and HO• radicals in abundance under neutral and alkaline pH was responsible for the catalytic degradation of PAHs. Our results provided new insights into the environmental applications of SBC for the green sustainable remediation of organics-contaminated sediments and aided in reduction of associated environmental and health risk.

Effects of spent mushroom substrate on the dissipation of polycyclic aromatic hydrocarbons in agricultural soil

Spent mushroom substrate (SMS) is an agricultural waste with a high potential for polycyclic aromatic hydrocarbons (PAH) removal in aged contaminated soils. In this study, fresh and air-dried Pleurotus ostreatus, Pleurotus eryngii, and Auricularia auricular SMSs were used to remove PAHs in agricultural soil under 60-day incubation. The potential of SMS in PAH dissipation was studied by detecting the dissipation rate and the soil physicochemical index, enzyme activity, PAH-degradation bacterial biomass, and microbial diversity. Results showed that SMS significantly enhanced the dissipation of PAHs and fresh SMS had a better effect than air-dried SMS. The highest dissipation rate of 16 PAHs was 34.5%, which was observed in soil amended with fresh P. eryngii SMS, and the PAH dissipation rates with low and high molecular weights were 41.3% and 19.4%, respectively. By comparison, fresh P. eryngii SMS presented high nutrient contents, which promoted the development of PAH-degrading bacteria and changed the soil bacterial community involved in degradation, thereby promoting the PAH dissipation. The lignin-degrading enzymes in fresh SMS were abundant, and the laccase and manganese peroxidase activities in the treatment of fresh P. eryngii SMS was higher than those in other treatments. Fresh P. eryngii SMS improved the relative abundance of Microbacterium, Rhizobium, and Pseudomonas in soil, which were all related to PAH degradation. Consequently, adding fresh P. eryngii SMS was an effective method for remediating aged PAH-contaminated agricultural soils.

The combination of biochar and plant roots improves soil bacterial adaptation to PAH stress: Insights from soil enzymes, microbiome, and metabolome

Polycyclic aromatic hydrocarbon (PAH) contamination in agricultural soils poses serious stress to the soil microbiome. With the broad application of biochar, however, the co-effects of biochar and plant roots on the bacterial responses to PAH stress remain unclear. Here, the effects of biochar and the rhizosphere on bacterial community structure and functions were analyzed by coupling enzyme activity tests, high-throughput sequencing, and soil metabolomics. The contents of available nutrients and dissolved organic carbon, enzyme activities, and carbon metabolism functions were improved by biochar and plant roots. With the combined effects of biochar and plant roots, sucrose and starch metabolism was mainly impacted, and the soil metabolite diversity decreased. There was a strong co-occurrence network among soil properties, bacterial members, and metabolites in the biochar-amended and rhizosphere soils, favoring bacterial resistance to PAH stress, and consequently, PAH removal. In light of the above results, we suggest that biochar application can efficiently improve bacterial functions in rhizosphere soil, and our results facilitate the development of in situ remediation programs in soil contaminated with PAHs.

Mechanism of biochar as a biostimulation strategy to remove polycyclic aromatic hydrocarbons from heavily contaminated soil in a coking plant

Twelve types of biochars were applied in a heavily contaminated soil from a coking plant to gain insights into the mechanism responsible for the microbial response to the addition of different biochar types into soil and biodegradation removal of polycyclic aromatic hydrocarbons (PAHs). The biochars primarily influenced the bacterial community at the genus level, while they strongly affected the fungal community not only at the genus level but also at the class and phylum levels. Principal component analysis (PCA) indicated that the inorganic minerals in biochars played a key role in stimulating microbial abundance (bacteria) and diversity (bacteria and fungi) in soil from the coking plant, and significantly negative correlations between the residual concentrations of PAHs in biochar-treated soils and the ash contents in biochars (generally, p < 0.05 for PAHs with 3–6 rings) were observed. These findings further suggested a positive effect of the inorganic minerals of biochars on stimulating changes in microorganisms, which could contribute to the biodegradation of PAHs in soil from the coking plant. Generally, the addition of biochars to the soils increased the biodegradation percentages of individual PAHs by 3.0–60.3% compared to those of the control. Among these biochars, rice straw-derived biochar pyrolyzed at 600 °C (RS6) effectively degraded PAHs from soil, with increasing biodegradation percentages of individual PAHs from 40.00% to 58.84%. This result was likely attributed to that the substantially specific Acidobacteria-related genera in RS6-treated soil were detected, which contributed to the effective biodegradation of PAHs. Accordingly, biochars pyrolyzed at a relatively high heating temperature with rice straw feedstock containing relatively high mineral nutrients are recommended for application to heavily PAH-contaminated soils.

An Integrated Approach to Remove PAHs from Highly Contaminated Soil: Electro-Fenton Process and Bioslurry Treatment

A combined process comprised of electro-Fenton and bioslurry (EF–bioslurry) was developed at lab scale for remediating a real coking plant soil with an initial polycyclic aromatic hydrocarbons (PAHs) content of 3605 mg/kg. Sodium citrate was used as a complexant to keep the iron in solution at near-neutral pH conditions for increasing the reaction rate. The appropriate order of application was to perform EF process followed by bioslurry, which was evaluated through analysis of degradation characteristics of individual processes. The optimum EF duration was assessed through an analysis of the induced changes in PAHs degradation and bacterial counts. The optimum application time of EF process was determined to be 24 h. The removal of PAHs was 95.2% for EF–bioslurry after 40 days, and the efficiency was increased by almost 150%, compared with the individual bioslurry treatment. The EF reaction caused significant cell death and high inhibition to polyphenol oxidase (PPO) activity of soil. The bacterial activity and counts in the slurry recovered rapidly after EF oxidation through the addition of raw soil (2%, w/w). Therefore, the combined process of EF–bioslurry process may be an efficient and promising approach for the remediation of highly organic-contaminated soil.

Effects of cellulose on polycyclic aromatic hydrocarbons removal and microbial community structure variation during anaerobic digestion of sewage sludge

Waste-activated sludge (WAS) with trace organic pollutants, e.g., polycyclic aromatic hydrocarbons (PAHs), has become an environmental concern. Anaerobic technology is a feasible option for WAS treatment due to its advantages of low-energy consumption and high-energy recovery compared to aerobic technology, but it still has many shortcomings, such as low biogas production and a low organic pollutant removal efficiency. Thus, this study investigated the effects of cellulose on PAHs degradation and microbial community structure variation during anaerobic digestion of sewage sludge. Four semicontinuous experiments were set by adding cellulose to sewage sludge based on the volatile solids (VS) concentration. The proportions of sludge VS to cellulose VS were 1:0 (CK), 1:0.2, 1:0.5 and 1:1. The results showed the following: (1) The biodegradation of 2-ring, 3-ring and 4-ring PAHs was enhanced by cellulose addition, with total PAHs removal efficiencies of 14.82%, 20.75% and 19.35%, respectively. (2) The abundance of bacteria that could degrade PAHs, such as Chloroflexi, Bacteroidetes, Aminicenantes, Planctomycetes and Spirochaeta, was obviously increased by cellulose addition. (3) The abundance of Methanosaeta during sludge anaerobic digestion was apparently increased by cellulose addition. Methanobacterium and Methanolinea appeared after cellulose addition, while they were not observed in the blank experiment.

Comparison of the Fe2+/H2O2 and Fe2+/PMS systems in simulated sludge: Removal of PAHs, migration of elements and formation of chlorination by-products

In this study, polycyclic aromatic hydrocarbons (PAHs) at practical concentrations in the simulated sludge treated by the Fe2+/H2O2 and Fe2+/peroxymonosulfate (PMS) systems were evaluated in terms of the PAHs (phenanthrene, anthracene, fluoranthene) removal, element migration, Cl− effect, and chlorination by-product formation. The results indicated that according to the removal rate of PAHs, the optimal dosage of the Fe2+/PMS system (∑PAHs removal rate was 64.66 ± 2.82 %) was 1/30 of that for the Fe2+/H2O2 system (∑PAHs removal rate was 78.63 ± 0.38 %). The elemental contents in the simulated sludge were mainly affected by the extent of advanced oxidation and the amount of generated iron flocs. By studying the PAHs removal, free chlorine formation, total organochlorine content, and PAHs products in Fe2+/H2O2/Cl- and Fe2+/PMS/Cl- systems, it was found that chlorine radicals (·Cl) had high reactivity with phenanthrene and fluoranthene, whereas dichloride anion radicals (Cl2·-) exhibited the opposite behavior. Furthermore, PAHs were oxidized by ·Cl and hydroxyl radical in the Fe2+/H2O2/Cl- system, whereas PAHs and their products were chlorinated by free chlorine and ·Cl in the Fe2+/PMS/Cl- system to six chlorinated by-products such as Cl-PAHs (9-Cl-phenanthrene, 2-Cl-anthracene, 9,10-Cl2-anthracene, 3-Cl-fluoranthene). These results provide some useful suggestions for the safe advanced oxidation process treatment of textile dyeing sludge.

Design, Simulation, and Environmental Assessment of an Adsorption-Based Treatment Process for the Removal of Polycyclic Aromatic Hydrocarbons (PAHs) from Seawater and Sediments in North Colombia

The presence of marine pollution in Cartagena Bay (Colombia) is an alarming environmental issue because of the ecotoxicological properties of contaminants such as polycyclic aromatic hydrocarbons (PAHs) that may affect the biodiversity of coastal ecosystems. In this sense, there is a need to propose alternatives to remediate the environmental pollution of such bodies of water. The aim of this work was to design an adsorption-based treatment process for the removal of PAHs from seawater and sediments. Two design cases were considered: (i) a base process without a PAH desorption unit and (ii) an alternative process including a PAH desorption unit. Both designs were simulated using Aspen Plus to obtain mass and energy balances. A parametric sensitivity analysis was carried out to determine optimum operating conditions for solvent recovery and treatment efficiency. The pressure and temperature of evaporators were selected as key parameters, as well as PAH loads in the influent. The environmental performance of base and alternative designs was also evaluated via waste reduction algorithm (WAR) methodology. A maximum recovered solvent flow rate was found when the evaporator operates at 56 °C and 0.81–0.83 atm. In addition, the total generation rate of potential environmental impacts (PEI) reported negative values for cases 1, 3, and 4 (−9.80 × 10–1, −9.25 × 10+1, −1.19 × 10+1, and 1.04 × 10+1 PEI/h). The major concern derived from this analysis is the high environmental impacts reached by the photochemical oxidation potential (PCOP) category associated with the use of hexane and acetone as solvents during PAH removal from sediments. In general, both designs of seawater and sediment treatment seem to be an environmentally friendly alternative for marine pollution remediation.

Effect of lignin and plant growth-promoting bacteria (Staphylococcus pasteuri) on microbe-plant Co-remediation: A PAHs-DDTs Co-contaminated agricultural greenhouse study

Due to the ecological toxicity and environmental residues, how to remove the persistent organic pollutants (POPs), especially of polycyclic-aromatic-hydrocarbons (PAHs) and dichloro-diphenyl-trichloroethanes (DDTs), from agricultural soil has captured the attention of scholars for a long time. To develop an effective and low-cost in situ co-remediation technique, five independent but complementary treatments were used on an over-standard PAHs-DDTs co-contaminated soil in an agricultural greenhouse. Experimental results identified that the combination of microbe (Bacillus methylotrophicus) - plant (Brassica rapa) could remove rhamnolipid activated PAHs and DDTs effectively after enhanced by Staphylococcus pasteuri. Also, the Benzoapyrene and total DDTs residue in Brassica rapa was up to the standard of National (China) food safety. The lignin enhanced the removal of high-rings PAHs and p-p’ DDE but reduced soil microbial biomass carbon and soil enzymes activity (polyphenol oxidase, invertase and acid phosphatase). Pearson correlation analysis showed that polyphenol oxidase activity was significantly related to the PAHs/DDTs dissipation rate. Our research suggested a new amendment that could remediate PAHs/DDTs co-contaminated agricultural soil without interrupting crop production, and the polyphenol oxidase activity should be considered as a micro-ecological indicator in this process.

Use of eco-friendly magnetic materials for the removal of polycyclic aromatic hydrocarbons and metals from environmental water samples

Abstract Highly toxic pollutants including polycyclic aromatic hydrocarbons (PAHs) and metals such as copper and lead are released into the environment from a variety of sources. One way to remove them from aqueous media is to use magnetic hybrid adsorbents that can be easily separated from the medium after the adsorption process. This work reports the synthesis of a magnetic hybrid matrix consisting of cobalt ferrite as the inorganic phase and natural organic matter (NOM) as the organic phase, where NOM was used instead of the traditional solvents. Tests showed that a hybrid produced using ferric sulfate (FAST) presented higher adsorption efficiency, compared to a hybrid produced using ferric chloride (FACT). PAH adsorption assays were performed using a deionized water solution containing benzo(a)anthracene (BaA), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene (BaP), and dibenzo(a,h)anthracene (DahA), which resulted in removal percentages in the range 83.9–97.6% (q = 41.3–53.7 mg g−1) at equilibrium after 30 min. Tests using real seawater and produced water samples confirmed the efficiency of the hybrid, with removal percentages in the range 86.5–96.3% (q = 43.2–48.1 mg g−1). The highest adsorption of PAHs was achieved using FAST, which was therefore selected for evaluation of metal removal, showing excellent adsorptive capacity, removing 84.5 and 92.0%, respectively, of the copper and lead present in seawater samples. Here, FAST provided efficient removal of both organic and inorganic species, demonstrating its potential for use in technological and environmental applications, including in the manufacturing sector.