Removal Of Polycyclic Aromatic Hydrocarbons Research Articles

Nanomaterial-mediated strategies for enhancing bioremediation of polycyclic aromatic hydrocarbons: A systematic review

Polycyclic aromatic hydrocarbons (PAHs) are pervasive organic pollutants in the environment that are formed as an outcome of partial combustion of organic matter. PAHs pose a significant threat to ecological systems and human health due to their cytotoxic and genotoxic effects. Therefore, an immediate need for effective PAH remediation methods is crucial. Although nanomaterials are effective for remediation of PAHs, concerns regarding environmental compatibility and sustainability remains. Therefore, this study emphasizes integration of nanomaterials with bioremediation methods, which might offer a more sustainable and ecofriendly approach to PAHs remediation. A systematic search was conducted through scholarly databases from 2013 to 2023. A total of 360 articles were scrutinized, among which 26 articles were selected that resonated with the application of nano-bioremediation. These literatures comprise both comparative analysis of bioremediation only as well as nano-bioremediation. There is an elevation of 18.9 % in PAHs removal of liquid-phase samples, when comparing bioremediation (52.2 %) with nano-bioremediation (71.1 %). A consistent trend was observed in soil samples, with bioremediation and nano-bioremediation that successfully remove PAHs, with 60.8 % and 75.1 % respectively, indicating a 14.3 % improvement. Furthermore, the review elaborated on the various features of nanomaterials that led to their efficiency in the bioremediation of PAH. The review also discussed the strategies of nano-bioremediation namely nanomaterial-assisted microbial degradation, nanomaterial-assisted enzyme-enhanced microbial activity, nanomaterial-immobilized microbial cells, nanomaterial-facilitated electron transfer, and even some eco-green approaches to remediate PAHs, like biogenic nanomaterial for PAHs.

Removal and mechanism investigation of polycyclic aromatic hydrocarbons in coconut oils by ionic liquids

Removal and mechanism investigation of polycyclic aromatic hydrocarbons in coconut oils by ionic liquids

Assembly and functional profile of rhizosphere microbial community during the Salix viminalis-AMF remediation of polycyclic aromatic hydrocarbon polluted soils

Arbuscular mycorrhizal fungi (AMF) are positive to the phytoremediation by improving plant biomass and soil properties. However, the role of AM plants to the remediation of polycyclic aromatic hydrocarbons (PAHs) is yet to be widely recognized, and the impact of AM plants to indigenous microbial communities during remediation remains unclear. In this work, a 90-day study was conducted to assess the effect of AMF-Salix viminalis on the removal of PAHs, and explore the impact to the microbial community composition, abundance, and function. Results showed that AMF-Salix viminalis effectively enhanced the removal of benzo[a]pyrene, and enriched more PAH-degrading bacteria, consisting of Actinobacteria, Chloroflexi, Sphingomonas, and Stenotrophobacter, as well as fungi including Basidiomycota, Pseudogymnoascus, and Tomentella. For gene function, AM willow enhanced the enrichment of genes involved in amino acid synthesis, aminoacyl-tRNA biosynthesis, and cysteine and methionine metabolism pathways. F. mosseae inoculation had a greater effect on alpha- and beta-diversity of microbial genes at 90 d. Additionally, AMF inoculation significantly increased the soil microbial biomass carbon and organic matter concentration. All together, the microbial community assembly and function shaped by AM willow promoted the dissipation of PAHs. Our results support the effectiveness of AM remediation and contribute to reveal the enhancing-remediation mechanism to PAHs using multi-omics data.

Characteristics and sources of polycyclic aromatic hydrocarbons in dew in urban ecosystems in Northeast China

The concentrations of polycyclic aromatic hydrocarbons (PAHs) in the atmospheres above major cities in Northeast China are relatively high. Dew is an effective way to settle and remove particulate and gaseous matter in the formation process. Notably, 16-PAH concentration dew analysis was conducted in four major cities (Harbin, Changchun, Shenyang and Dalian) from April to November 2023. In the study area, 2–3-ring PAHs dominated in dew in both the dissolved and particle phases, followed by 4-ring and 5–6-ring PAHs. Phe was the most common individual PAH in dew. Because PAHs in wet deposition are closely related to those in the atmosphere, the concentration of PAHs in dew was much lower than that in snow. The proportions of the gaseous-phase scavenging ratio (Wg) to the total scavenging ratio (Wt) in Harbin, Changchun, Shenyang and Dalian increased with increasing temperature, reaching 22.98%, 29.02%, 30.71% and 33.22%, respectively, which indicated that the ability of dew to remove PAHs in the particle phase was greater than that to remove PAHs in the gas phase. The concentration of dissolved-phase PAHs in dew was lower than that of particle-phase PAHs. The total PAH fluxes were 43.25, 33.35, 32.16, and 25.63 ng/m2·d in Harbin, Changchun, Shenyang and Dalian, respectively, decreasing from north to south. The dew amount was much smaller than the rainfall and snow amount (by two orders of magnitude), and the PAH flux in dew was much lower than that in rain and snow. Isomeric ratio assessment coupled with principal component analysis (PCA) indicated that the source of PAHs in dew was a combination of vehicle emissions and biomass and coal combustion. PAHs in dew mainly originated from local sources rather than from long-range atmospheric transport. This study revealed the effects of PAHs in dew on the air quality and the removal of PAHs by dew.

Insights into relationship between microbial community-induced polycyclic aromatic hydrocarbons degradation and soluble organic matter transformation during vermiculite-amended sewage sludge composting

Vermiculite is a natural clay mineral with unique properties that are widely used in plant cultivation, soil remediation, and solid waste management. This study investigated the relationship between microbial community-induced polycyclic aromatic hydrocarbons (PAHs) degradation and dissolved organic matter (DOM) transformation during vermiculite-amended composting of sewage sludge. Four treatments with varying vermiculite percent compositions, 0%, 1%, 5%, and 10%, mixed with initial mix waste, were designed and then composted for 33 days. The results showed that the addition of 1% vermiculite caused the highest losses of 82.19%, 52.98%, and 69.00% for LMW-PAHs (2–3 rings), HMW-PAHs (4–6 rings), and total PAHs respectively compared to other treatments. Spectral and community analyses revealed that 1% vermiculite enhanced the PAHs losses by functional networking of key genera and promoting the aromatization and humification of DOM to format the micelles with PAHs. The transformation and utilization of DOM driven by key genera Acinetobacter, Ochrobactrum, Pseudoxanthomonas, and Bacillus were the important impact factors for the losses of PAHs. Finally, this study provides new insights and a guide for applying vermiculite to sludge composting for PAHs removal.

Synergism of endophytic microbiota and plants promotes the removal of polycyclic aromatic hydrocarbons from the Alfalfa rhizosphere

Endophytic bacteria can promote plant growth and accelerate pollutant degradation. However, it is unclear whether endophytic consortia (Consortium_E) can stabilize colonisation and degradation. We inoculated Consortium_E into the rhizosphere to enhance endophytic bacteria survival and promote pollutant degradation. Rhizosphere-inoculated Consortium_E enhanced polycyclic aromatic hydrocarbon (PAH) degradation rates by 11.5–13.1 % compared with sole bioaugmentation and plant treatments. Stable-isotope-probing (SIP) showed that the rhizosphere-inoculated Consortium_E had the largest number of degraders (8 amplicon sequence variants). Furthermore, only microbes from Consortium_E were identified among the degraders in bioaugmentation treatments, indicating that directly participated in phenanthrene metabolism. Interestingly, Consortium_E reshaped the community structure of degraders without significantly altering the rhizosphere community structure, and strengthened the core position of degraders in the network, facilitating close interactions between degraders and non-degraders in the rhizosphere, which were crucial for ensuring stable functionality. The synergistic effect between plants and Consortium_E significantly enhanced the upregulation of aromatic hydrocarbon degradation and auxiliary degradation pathways in the rhizosphere. These pathways showed a non-significant increasing trend in the uninoculated rhizosphere compared with the control, indicating that Consortium_E primarily promotes rhizosphere effects. Our results explore the Consortium_E bioaugmentation mechanism, providing a theoretical basis for the ecological restoration of contaminated soils.

Novel insights into the factors influencing rhizosphere reactive oxygen species production and their role in polycyclic aromatic hydrocarbons transformation

Reactive oxygen species (ROS) are recognised as pivotal biogeochemical process drivers. However, the factors influencing ROS production in the rhizosphere and their role in pollutant transformation remain elusive. We investigated ROS with a focus on spatiotemporal variations in superoxide radicals (O2•−), hydrogen peroxide (H2O2), and hydroxyl radicals (•OH) in the rhizosphere of maize during root development, and elucidated the impact of environmental conditions on ROS production. In-situ visualisation by fluorescence imaging showed that ROS hotspots gradually shifted from seminal to lateral roots during maize growth, indicating that newly developed roots are the major contributors to ROS production. The three types of ROS contents changed with root growth, suggesting that root development regulates ROS production. The ROS contents reached a maximum at 25 °C and 45% maximum field capacity. Both ambient temperature and soil moisture indirectly influenced ROS production by regulating the release of root exudates to induce changes in water-soluble phenols and dissolved organic carbon (DOC). In contrast, ROS content gradually increased with oxygen availability, which directly mediated ROS generation by acting as a precursor. More interestingly, the presence of polycyclic aromatic hydrocarbons (PAHs) significantly enhanced ROS generation, which further promoted PAH removal with a contribution of 31.4–43.3%. These findings provide new insights into the occurrence, distribution, and environmental effects of ROS in the rhizosphere.

Adsorption of Polycyclic Aromatic Hydrocarbons from Wastewater Using Iron Oxide Nanomaterials Recovered from Acid Mine Water: A Review

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic pollutants known for their persistence and potential carcinogenicity. Effective removal techniques are required since their presence in wastewater poses serious threats to human health and the environment. In this review study, iron oxide nanomaterials (IONs), a by-product of mining operations, recovered from acid mine water are used to investigate the adsorption of PAHs from wastewater. The mechanisms of PAH adsorption onto IONs are investigated, with a focus on the effects of concentration, temperature, and pH on adsorption efficiency. The better performance, affordability, and reusable nature of IONs are demonstrated by comparative studies with alternative adsorbents such as activated carbon. Economic and environmental ramifications highlight the benefits of employing recovered materials, while case studies and real-world applications show how effective IONs are in removing PAHs in the real world. This review concludes by discussing potential future developments in synthesis processes, areas for more research, and emerging trends in nanomaterial-based adsorption. This research intends to contribute to the development of more effective and sustainable wastewater treatment technologies by offering a thorough assessment of the present and future potential of employing IONs for PAH removal from wastewater.

Surfactant-enhanced mobilization of polycyclic aromatic hydrocarbons from an historically contaminated marine sediment: Study of surfactants’ concentration effect and continuous test for sediment flushing simulation

Contamination of marine sediments by polycyclic aromatic hydrocarbons (PAHs) poses a significant environmental threat, necessitating effective remediation strategies. This paper investigates the application of surfactants, both synthetic and natural, for the remediation of PAH-contaminated sediments, providing a systematic guideline for the preliminary selection of surfactants for flushing/washing operations, the optimal operative conditions, and the technical approach for PAH mobilization, especially in the context of a real aged contamination scenario. The study included a batch configuration test to evaluate the effect of surfactant concentration on PAH mobilization. Subsequently, a continuous configuration column experiment was performed to simulate a flushing operation of contaminated sediment. The study of process conditions highlighted that the increase in surfactant concentration led to a significant increase in PAH removal from the sediment, reaching almost 30 % efficiency using a 5 % wt surfactant solution. The column test showed great efficiency of the investigated surfactants in PAH mobilization through the flushing process of the contaminated matrix, resulting in 30 times greater efficiency than water within a much smaller pore volume range.

Simultaneous desulfurization and dearomatization of simulated straight-run diesel with novel green DBN-based ionic liquids

Given the surplus of diesel fuel in China and the extensive utilization of renewable energy sources, there is a growing inclination to eliminate organic sulphur and aromatic hydrocarbons from diesel fuel for its application as high-quality ethylene cracking feedstock. In this study, a series of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN)-based ionic liquids with [DBNH]+ as the cation and imidazole as the anion were designed and synthesized for the simultaneous desulfurization and dearomatization of straight-run diesel fuel. Considering factors such as extractant stability, residue content in oil, and separation performance, [DBNH][Tr], exhibiting excellent performance characteristics, was screened as the optimal extractant. Following three-stage cross-flow extraction with an extractant/oil ratio of 3:1 at 30 °C, complete removals of sulfides (benzothiophene) and polycyclic aromatic hydrocarbons (1-methylnaphthalene) were achieved while saturated alkanes reached up to 95.8 wt%, making it suitable for ethylene cracking applications. The interaction mechanisms between ionic liquids and oil components were revealed by atoms in molecules (AIM) topology analysis, independent gradient model based on Hirshfeld partition (IGMH) analysis, and symmetric adaptive perturbation theory energy decomposition techniques, revealing that dispersion-dominated van der Waals (VDW) forces primarily govern interactions due to π-π stacking.

Innovative utilization of plant-derived dissolved organic matter to promote polycyclic aromatic hydrocarbons removal in constructed wetlands: Unraveling the synergy among substrate adsorption, plant uptake, and microbial degradation

Dissolved organic matter (DOM) is a group of active compounds which can influence Polycyclic aromatic hydrocarbons (PAHs) migration or biodegradation, thus may help solve the challenge of inefficient removal of PAHs in constructed wetlands (CWs). CWs with plant derived DOM (PA-A) or fulvic acid addition were set up to explore their influence on CWs performance. Results demonstrated significantly enhanced removal of phenanthrene (PHE, 7.81 % ± 2.07 %), benzo[a]pyrene (BaP, 7.11 % ± 1.91 %), and benzo[k]fluoranthrene (BkF, 5.04 % ± 3.48 %) by DOM. With DOM addition, PAHs concentration in substrate decreased while the bioavailability increased. Notably, in the shallow substrate, PHE content decreased by 19.61%–23.53 %, and BaP bioavailability increased by 1.88–2.00 times. The active absorption and migration of PAHs in P.australis were enhanced, resulting in the total concentrations of PAHs reaching 1743.66 ng/g in the roots and 398.77 ng/g in the leaves in PA-A. Biodegradation was calculated as the primary pathway for PAHs removal by mass balance. Ochrobactrum, Xanthobacteraceae, Rhizobium and Burkholderiaceae relating to PAHs biodegradation were dominate strains. This study unraveled the synergy among substrate adsorption, plant uptake and microbial degradation during PAHs removal, and offered novel insights into the utilization of wetland plants.

Efficient removal of polycyclic aromatic hydrocarbons from aqueous solutions using green cyclodextrin-maltodextrin nanosponge incorporated polyvinyl alcohol cryogel

Developing efficient adsorbents for removing polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions is a significant and worthwhile approach. In this study, we showcase a method for fabricating β-cyclodextrin-maltodextrin nanosponges (βCD-MD) incorporated polyvinyl alcohol (PVA) cryogel for removing PAHs from aqueous solutions. The composite nanosponges enhanced the adsorption efficiency of PAHs such as Naphthalene, Acenaphthene, Fluorene, Phenanthrene, Anthracene, Fluoranthene, Pyrene, and Benzo[a]pyrene from water samples and the porous PVA cryogel helped to entrap and prevent the loss of the adsorbent. This efficacy was attributed to the strong affinities of PAHs toward βCD-MD nanosponges, facilitated by hydrophobic interactions between the analytes and the hydrophobic inner region present in both dextrins. The removal efficiency of the prepared βCD-MD/PVA composite cryogel was more than 95 % for all 8 PAHs (C0 = 5.0 mg/L) in less than 30 min, and the experimental data were well described by the Freundlich isotherm and the pseudo-second-order kinetic model. Additionally, the βCD-MD/PVA composite cryogel exhibited a maximum adsorption capacity ranging from 16.34 to 18.49 mg/g for eight PAHs. Moreover, the thermodynamic study revealed that the adsorption of PAHs was an endothermic and spontaneous process. The βCD-MD/PVA composite cryogel exhibited an abundance of polar functional groups along with numerous hydrophobic cavities and regions. It demonstrated high mechanical and thermal stability and maintained high removal efficiency even after seven adsorption–desorption cycles. Overall, it was concluded that βCD-MD/PVA composite cryogel can be utilized as a high-performance, eco-friendly, and sustainable alternative for PAH removal.

Assessing the Impact of Pre-Soaking to Enhance Laundering Efficacy of Firefighter Turnout Gear.

Firefighters are exposed to hazardous chemicals at fire scenes, including polycyclic aromatic hydrocarbons (PAHs) among many others, which pose significant health risks. Current laundering practices are ineffective at removing persistent contaminants from turnout gear, necessitating further research to optimize cleaning methods. This study explores the impact of presoaking prior to the laundering process and the factors that can affect its effectiveness, including the presoaking duration and detergent concentration, in PAH removal when laundering. For this, contaminated fabric swatches were subjected to various presoaking durations (1, 3, and 12 h) and detergent concentrations (99:1 and 90:10 water-to-detergent ratios) before undergoing bench-scale washing. The cleaning efficacy was assessed for 16 PAH compounds, including both low-molecular-weight (LMW) PAHs and high-molecular-weight (HMW) PAHs. Moreover, the removal mechanisms of PAHs from turnout gear were fundamentally explained using partition coefficients and standard affinities with different parameters during washing. The results demonstrate that 3 h and 12 h of presoaking lead to 2.8 and 4.3 times greater HMW PAH removal, respectively. After 12 h of presoaking in a 90:10 water-to-detergent ratio, 97% of the LMW PAHs and 78% of the HMW PAHs were removed, compared to only an 11% removal of the HMW PAHs with a 99:1 ratio. Additionally, direct washing with a 90:10 ratio achieved comparable efficacy to that of presoaking with the same water-to-detergent ratio, indicating the crucial role of detergent concentration during laundering. These findings offer valuable insights for optimizing firefighter safety practices, emphasizing the role of presoaking and the appropriate methods to perform presoaking to mitigate firefighters' occupational exposure risks to toxic substances and ensure gear reliability.

Efficient PAHs removal and CO2 fixation by marine microalgae in wastewater using an airlift photobioreactor for biofuel production

Microalgae cultures have emerged as a promising strategy in diverse areas, ranging from wastewater treatment to biofuel production, thus contributing to the search for carbon neutrality. These photosynthetic organisms can utilize the resources present in wastewater and fix atmospheric CO2 to produce biomass with high energy potential. In this study, the removal efficiency of Polycyclic Aromatic Hydrocarbons (PAHs), CO2 fixation and lipid content in the biomass produced from microalgae grown in airlift photobioreactor were evaluated. Four mesoscale cultures were carried out: Control (Seawater + Conway medium), Treatment A (Oil Produced Water + Poultry Effluent Water), Treatment B (Poultry Effluent Water + Seawater) and Treatment C (Oil Produced Water, Seawater and nutrients). The impact of biostimulation, through the addition of nutrients, on PAHs removal efficiency (up to 90%), CO2 fixation rate (up to 0.20 g L−1 d−1) and the composition of the generated biomass was observed. Primarily, the addition of nitrates to the culture medium impacted CO2 fixation rate of the microalgae. In addition, a direct correlation was observed between PAHs removal and lipid accumulation in the biomass, up to 36% in dry weight, demonstrating microalgae's ability to take advantage of the organic carbon (PAHs) present in the culture medium to generate lipid-rich biomass. The concentration of polysaccharides in the biomass obtained did not exceed 12% on a dry weight basis, and the Higher Heating Value (HHV) ranged between 17 and 21 MJ kg−1. Finally, the potential of generating hydrogen through pyrolysis was highlighted, taking advantage of the characteristics of biomass as a conversion route to produce biofuels. These results show that microalgae are effective in wastewater treatment and have great potential in producing biofuels, thus contributing to the transition towards more sustainable energy sources and climate change mitigation.

Benzo(b)fluoranthene and benzo(k)fluoranthene removal by microalgae in the presence of triazine herbicides: Matrix solid-phase dispersion and solid-phase extraction (MSPD/SPE) for HPLC-UV analysis of the different culture components

Over the last decade, human activities in the industrial and agricultural sectors have significantly increased the concentration of persistent and harmful pollutants in aquatic ecosystems. The use of microorganisms is a green strategy for the bio-removal of certain contaminants. However, other pollutants in the same ecosystems can reduce their degrading activity and even affect their survival. Therefore, this study aimed to evaluate the efficiency of benzo(b)fluoranthene (BbF) and benzo(k)fluoranthene (BkF) removal by Selenastrum capricornutum in the presence of triazine herbicides, compounds mainly used in broadleaf weeds. The interest of this work focused on identifying in which of the microalgal components the degrading activity is best evidenced and affected. For this purpose, the use of solid-phase extraction (SPE) and matrix solid-phase dispersion (MSPD) extraction procedures and HPLC-UV analysis allowed the BbF and BkF trace quantification in biomass, liquid medium, and cell lysate separately from cultures exposed to these polycyclic aromatic hydrocarbons (PAHs) alone or with herbicides. The recovery percentages were between 78 and 94 %, good linearity (r2 ≈ 0.99), precision values measured as RSD < 15 %, and limits of detection (LOQs) at levels of ng mL−1 and ng mg−1 were obtained. The individual PAH amounts measured in the components of microalgae cultures show similar removal kinetics (removal percentages: 82–89 %). Likewise, the analysis demonstrated that the removal of PAHs is not affected in the presence of triazine herbicides (atrazine and cyanazine) and with similar removal percentages (79–86 %) compared to those cultures exposed to individual PAHs (74–83 %). These results support the possible real-world applications of PAH removal by extracts from S. capricornutum in aquatic environments contaminated with PAHs and near agriculture areas where triazine herbicides are used.

Rapid removal of polycyclic aromatic hydrocarbons from water using sulfonated mesoporous polymeric adsorbents

Polycyclic aromatic hydrocarbons (PAHs) are potential hazards and are often found in aquatic environments through industrial effluents. Herein, we report sulfonated modified mesoporous thermoplastic polymers to remove potentially carcinogenic PAHs from water rapidly. Mesoporous structures of the thermoplastics (polystyrene, polysulfone, and polycarbonate) were attained using nano-crystallization induced phase separation by flash-freezing route. Sulfonation reactions carried out hydrophilic surface modifications of the polymers. Their ion exchange capacity (IEC) values determined the degree of sulfonation. The sulfonated mesoporous polymers were characterized using Fourier-Transform Infra-Red spectroscopy (FT-IR) for functional groups, Field-Emission Scanning Electron Microscopy (FE-SEM) for mesoporous structures, Brunauer-Emmet-Teller method for specific surface area, and Barrett-Joyner-Halenda method for pore size distributions. The IEC values for the sulfonated mesoporous polymers range from 1.13 – 1.15 × 10-2 meq. g−1. The sulfonated mesoporous polymers showed high specific surface areas (176–185 m2/g) with pore sizes ranging from 5 nm to 9 nm. The sulfonated mesoporous polymers rapidly adsorb PAHs from nearly saturated water solutions within 60 min with % removal of over 98 %. The adsorbents can also be easily regenerated by simple washing with methanol and are found to be recycled up to 10 cycles with only a marginal reduction in adsorption capacities.

Mechanistic Implications of the Varying Susceptibility of PAHs to Pyro-Catalytic Treatment as a Function of Their Ionization Potential and Hydrophobicity.

Transition metal catalysts in soil constituents (e.g., clays) can significantly decrease the pyrolytic treatment temperature and energy requirements for efficient removal of polycyclic aromatic hydrocarbons (PAHs) and, thus, lead to more sustainable remediation of contaminated soils. However, the catalytic mechanism and its rate-limiting steps are not fully understood. Here, we show that PAHs with lower ionization potential (IP) are more easily removed by pyro-catalytic treatment when deposited onto Fe-enriched bentonite (1.8% wt. ion-exchanged content). We used four PAHs with decreasing IP: naphthalene > pyrene > benz(a)anthracene > benzo(g,h,i)perylene. Density functional theory (DFT) calculations showed that lower IP results in stronger PAH adsorption to Fe(III) sites and easier transfer of π-bond electrons from the aromatic ring to Fe(III) at the onset of pyrolysis. We postulate that the formation of aromatic radicals via this direct electron transfer (DET) mechanism is the initiation step of a cascade of aromatic polymerization reactions that eventually convert PAHs to a non-toxic and fertility-preserving char, as we demonstrated earlier. However, IP is inversely correlated with PAH hydrophobicity (log Kow), which may limit access to the Fe(III) catalytic sites (and thus DET) if it increases PAH sorption to soil OM. Thus, ensuring adequate contact between sorbed PAHs and the catalytic reaction centers represents an engineering challenge to achieve faster remediation with a lower carbon footprint via pyro-catalytic treatment.

Remediation of phenanthrene contaminated soil by persulphate coupled with Pseudomonas aeruginosa GZ7 based on oxidation prediction model.

Chemical oxidation coupled with microbial remediation has attracted widespread attention for the removal of polycyclic aromatic hydrocarbons (PAHs). Among them, the precise evaluation of the feasible oxidant concentration of PAH-contaminated soil is the key to achieving the goal of soil functional ecological remediation. In this study, phenanthrene (PHE) was used as the target pollutant, and Fe2+-activated persulphate (PS) was used to remediate four types of soils. Linear regression analysis identified the following important factors influencing remediation: PS dosage and soil PHE content for PHE degradation, Fe2+ dosage, hydrolysable nitrogen (HN), and available phosphorus for PS decomposition. A comprehensive model of "soil characteristics-oxidation conditions-remediation effect" with a high predictive accuracy was constructed. Based on model identification, Pseudomonas aeruginosa GZ7, which had high PAHs degrading ability after domestication, was further applied to coupling repair remediation. The results showed that the optimal PS dose was 0.75% (w/w). The response relationship between soil physical, chemical, and biological indicators at the intermediate interface and oxidation conditions was analysed. Coupled remediation effects were clarified using microbial diversity sequencing. The introduction of Pseudomonas aeruginosa GZ7 stimulated the relative abundance of Cohnella, Enterobacter, Paenibacillus, and Bacillus, which can promote material metabolism and energy transformation during remediation.

A case study on microlitter and chemical contaminants: Assessing biological effects in the southern coast of the Gulf of Finland (Baltic sea) using the mussel Mytilus trossulus as a bioindicator

Chemical and microlitter (ML) pollution in three Estonian coastal areas (Baltic Sea) was investigated using mussels (Mytilus trossulus). Polycyclic aromatic hydrocarbons (PAH) in mussel tissues were observed in moderate levels with high bioaccumulation factors for the more hydrophilic and low molecular weight PAH (LMW PAH), namely anthracene and fluorene. Tissue concentrations of polybrominated diphenyl ethers (PBDE) and cadmium within mussel populations exceeded the Good Environmental Status thresholds by more than 200% and 60%, respectively. Multiple contamination at the Muuga Harbour site by tributyltin, high molecular weight PAH, including the highly toxic benzo[c]fluorene and PBDE, coincided with the inhibition of acetylcholinesterase activity and a lower condition index of the mussels. The metabolization and removal of bioaccumulated LMW PAH, reflected in the dominance of oxy-PAH such as anthracene-9,10-dione, is likely associated with the increased activity of glutathione S-transferase in caged mussels. Only a few microplastic particles were observed among the ML in mussel tissues, with coloured cellulose-based microfibers being the most prevalent. The average concentration of ML in mussels was significantly higher at the harbour area than at other sites. The integrated biomarker response index values allowed for the differentiation of pollution levels across studied locations representing high, intermediate, and low pollution levels within the studied area.

Sphingobium sp. SJ10-10 encodes a not-yet-reported chromate reductase and the classical Rieske dioxygenases to simultaneously degrade PAH and reduce chromate

Both polycyclic aromatic hydrocarbons (PAHs) and heavy metals persist in the environment and are toxic to organisms. Their co-occurrence makes any of them difficult to remove during bioremediation and poses challenges to environmental management and public health. Microorganisms capable of effectively degrading PAHs and detoxifying heavy metals concurrently are required to improve the bioremediation process. In this study, we isolated a new strain, Sphingobium sp. SJ10–10, from an abandoned coking plant and demonstrated its capability to simultaneously degrade 92.6 % of 75 mg/L phenanthrene and reduce 90 % of 3.5 mg/L hexavalent chromium [Cr(VI)] within 1.5 days. Strain SJ10–10 encodes Rieske non-heme iron ring-hydroxylating oxygenases (RHOs) to initiate PAH degradation. Additionally, a not-yet-reported protein referred to as Sphingobium chromate reductase (SchR), with low sequence identity to known chromate reductases, was identified to reduce Cr(VI). SchR is distributed across different genera and can be classified into two classes: one from Sphingobium members and the other from non-Sphingobium species. The widespread presence of SchR in those RHO-containing Sphingobium members suggests that they are excellent candidates for bioremediation. In summary, our study demonstrates the simultaneous removal of PAHs and Cr(VI) by strain SJ10–10 and provides valuable insights into microbial strategies for managing complex pollutant mixtures.