Removal Of Aromatic Hydrocarbons Research Articles

Crude Oil Biodegradation by a Biosurfactant-Producing Bacterial Consortium in High-Salinity Soil

Bioremediation is a promising strategy to remove crude oil contaminants. However, limited studies explored the potential of bacterial consortia on crude oil biodegradation in high salinity soil. In this study, four halotolerant strains (Pseudoxanthomonas sp. S1-2, Bacillus sp. S2-A, Dietzia sp. CN-3, and Acinetobacter sp. HC8-3S), with strong environmental tolerance (temperature, pH, and salinity), distinctive crude oil degradation, and beneficial biosurfactant production, were combined to construct a bacterial consortium. The inoculation of the consortium successfully degraded 97.1% of total petroleum hydrocarbons in 10 days, with notable removal of alkanes, cycloalkanes, branched alkanes, and aromatic hydrocarbons. Functional optimization showed that this consortium degraded crude oil effectively in a broad range of temperature (20–37 °C), pH (6–9), and salinity (0–100 g/L). In salt-enriched crude-oil-contaminated soil microcosms, the simultaneous treatment of bioaugmentation and biostimulation achieved the highest crude oil degradation rate of 568.6 mg/kg/d, compared to treatments involving abiotic factors, natural attenuation, biostimulation, and bioaugmentation after 60 days. Real-time PCR targeting the 16S rRNA and alkB genes showed the good adaptability and stability of this consortium. The degradation property of the constructed bacterial consortium and the engineered consortium strategy may have potential use in the bioremediation of crude oil pollution in high-salinity soil.

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.

Oil palm waste-derived adsorbents for the sequestration of selected polycyclic aromatic hydrocarbon in contaminated aqueous medium

Carbonaceous adsorbents were synthesized from palm kernel shell and palm mesocarp fiber for the adsorption of phenanthrene (PHE) and the highly carcinogenic-benzo(a)pyrene (BaP). The structure and properties of the activated biochar were characterized using standardized analytical tools. The microscopic examinations carried out with SEM and BET results revealed mesoporous structures and interstitial spaces in the activated samples (AB-PKS and AB-PMS). Powder X-ray diffraction (PXRD) results showed that prepared sorbents are amorphous and that activation affected the amorphous cellulose on the surface of the microfibrils which led to a decrease in the intensity of some peaks. Fourier-transform infrared spectroscopy (FTIR) affirms the availability of surface moieties that may promote polycyclic aromatic hydrocarbon (PAH) removal or decontamination of aqueous media. The sorption isotherm and effect of pH on the adsorption of PHE and BaP onto the activated palm kernel shell (AB-PKS) and activated palm mesocarp fiber (AB-PMF) were investigated. The isotherm studies and error analysis (SSE and R2) confirm that the Freundlich model best fits experimental results for AB-PMF; while, the Langmuir model best describes AB-PKS sorption of BaP and PHE, respectively. The optimal removal efficiency for PHE was between 84 and 100% while that of BaP was between 68 and 87% with maximum adsorption capacity (qmax) of 19.38–21.98 mg/g and 1.24–13.26 mg/g, respectively. The optimum pH condition for removing PHE is less than 7 and above 7 for BaP. Therefore, the conversion of waste materials to useful sorbents, as well as preliminary adsorption test results obtained suggests a cleaner and cost-effective pathway for waste management and water treatment.

Simultaneous removal of aliphatic and aromatic crude oil hydrocarbons by Pantoea agglomerans isolated from petroleum-contaminated soil in the west of Iran.

Hydrocarbons are considered as one of the most common and harmful environmental pollutants affecting human health and the environment. Bioremediation as an environmentally friendly, highly efficient, and cost-effective method in remediating oil-contaminated environments has been interesting in recent decades. In this study, hydrocarbon degrader bacterial strains were isolated from the highly petroleum-contaminated soils in the Dehloran oil field in the west of Iran. Out of 37 isolates, 15 can grow on M9 agar medium that contains 1.5 gL-1 of crude oil as the sole carbon source. The morphological, biochemical, and 16SrRNA sequencing analyses were performed for the isolates. The choosing of the isolates as the hydrocarbon degrader was examined by evaluating the efficacy of their crude oil removal at a concentration of 10gL-1 in an aqueous medium. The results showed that five isolates belonging to Pseudomonas sp., Pseudomonas oryzihabitans, Roseomonas aestuarii, Pantoea agglomerans, and Arthrobacter sp. had a hyper hydrocarbon-degrading activity and they could remove more than 85% of the total petroleum hydrocarbon (TPH) after 96h. The highest TPH removal of about 95.75% and biodegradation rate of 0.0997gL-1h-1 was observed for P. agglomerans. The gas chromatography-mass spectroscopy (GC-MS) analysis was performed during the biodegradation process by P. agglomerans to detect the degradation intermediates and final products. The results confirmed the presence of intermediates such as alcohols and fatty acids in the terminal oxidation pathway of alkanes in this biodegradation process. A promising P. agglomerans NB391 strain can remove aliphatic and aromatic hydrocarbons simultaneously.

Characteristics of polycyclic aromatic hydrocarbons (PAHs) removal by nanofiltration with and without coexisting organics

Polycyclic aromatic hydrocarbons (PAHs) are contaminants of great concern owing to their persistence, toxicity, and bioaccumulation in aquatic environments. In this study, nanofiltration (NF) was used to investigate the removal of naphthalene (NAP) and phenanthrene (PHE) using three membranes of NF270, NF90, and DK. Subsequently, we examined the effects of coexisting organics on PAHs removal. Based on the results, DK was determined to be the optimal membrane for removing PAHs by comparing the membrane flux and pollutant rejection. The membrane flux reached 34.32 L/m2·h, and the NAP and PHE rejections were 92.21% and 97.85%, respectively, at transmembrane pressure (TMP) of 5 bar using DK. Coexisting organics decreased the membrane fluxes of NF270 and DK in the following order: protein > glucose > humic acid. The NAP and PHE rejections were obviously improved using NF270 in the following order: humic acid > protein > glucose. The PHE rejection was slightly improved using DK. A low concentration of organics could reduce the NAP rejection using DK; however, the NAP rejection could be restored at high concentrations of organics, except for humic acid. Coexisting organics could cause severe membrane fouling. The order of the effect of different coexisting organics on membrane fouling was protein > humic acid > glucose. The total investment and operating costs were about 1.47 and 0.187 million dollars, respectively, for treating PAHs solution using DK when the feed flow was 300 m3/d.

Biochars assisted phytoremediation of polycyclic aromatic hydrocarbons contaminated agricultural soil: Dynamic responses of functional genes and microbial community

A biochar-intensified phytoremediation experiment was designed to investigate the dynamic effects of different biochars on polycyclic aromatic hydrocarbon (PAH) removal in ryegrass rhizosphere contaminated soil. Maize and wheat straw biochar pyrolyzed at 300 °C and 500 °C were amended into PAH-contaminated soil, and then ryegrass (Lolium multiflorum L.) was planted for 90 days. Spearman's correlations among PAH removal, enzyme activity, abundance of PAH-ring hydroxylating dioxygenase (PAH-RHDα), and fungal and bacterial community structure were analyzed to elucidate the microbial degradation mechanisms during the combined remediation process. The results showed that 500 °C wheat straw biochar had higher surface area and more nutrients, and significantly accelerated the phytoremediation of PAHs (62.5 %), especially for high molecular weight PAH in contaminated soil. The activities of urease and dehydrogenase and the abundance of total and PAH-degrading bacteria, which improved with time by biochar and ryegrass, had a positive correlation with the removal rate of PAHs. Biochar enhanced the abundance of gram-negative (GN) PAH-RHDα genes. The GN PAH-degraders, Sphingomonas, bacteriap25, Haliangium, and Dongia may play vital roles in PAH degradation in biochar-amended rhizosphere soils. Principal coordinate analysis indicated that biochar led to significant differences in fungal community structures before 30 days, while the diversity of the bacterial community composition depended on planting ryegrass after 60 days. These findings imply that the structural reshaping of microbial communities results from incubation time and the selection of biochar and ryegrass in PAH-contaminated soils. Applying 500 °C wheat straw biochar could enhance the rhizoremediation of PAH-contaminated soil and benefit the soil microbial ecology.

Persistent polycyclic aromatic hydrocarbons removal from sewage sludge-amended soil through phytoremediation combined with solid-state ligninolytic fungal cultures

Polycyclic aromatic hydrocarbons (PAHs) are widely present in the environment, causing increasing concern because of their impact on soil health, food safety and potential health risks. Four bioremediation strategies were examined to assess the dissipation of PAHs in agricultural soil amended with sewage sludge over a period of 120 days: soil-sludge natural attenuation (SS); phytoremediation using maize (Zea mays L.) (PSS); mycoremediation (MR) separately using three white-rot fungi (Pleurotus ostreatus, Phanerochaete chrysosporium and Irpex lacteus); and plant-assisted mycoremediation (PMR) using a combination of maize and fungi. In the time frame of the experiment, mycoremediation using P. chrysosporium (MR-PH) exhibited a significantly higher (P < 0.05) degradation of total PAHs compared to the SS and PSS treatments, achieving a degradation rate of 52 %. Both the SS and PSS treatments demonstrated a lower degradation rate of total PAHs, with removal rates of 18 % and 32 %, respectively. The PMR treatments showed the highest removal rates of total PAHs at the end of the study, with degradation rates of 48–60 %. In the shoots of maize, only low- and medium-molecular-weight PAHs were found in both the PSS and PMR treatments. The calculated translocation and bioconversion factors always showed values < 1. The analysed enzymatic activities were higher in the PMR treatments compared to other treatments, which can be positively related to the higher degradation of PAHs in the soil.

Overcoming methanogenesis barrier to acid inhibition and enhancing PAHs removal by granular biochar during anaerobic digestion

Alleviating acid inhibition is the most important for optimizing anaerobic digestion (AD), but the recalcitrant organic pollutants in digestates have long been ignored. In this study, we aimed to simultaneously enhance both organics bio-methanation and recalcitrant polycyclic aromatic hydrocarbons (PAHs) removal in AD system by using granule biochar and short-term ethanol stimulation. The results showed that adding biochar effectively alleviated volatile fatty acids (VFAs) accumulation and achieved 313.6 mL CH4/d•g COD average yield. Meanwhile, the efficiency of phenanthrene (PHE) biodegradation, as the model PAHs pollutant, was significantly promoted by 37.1%. Additionally, more and compact extracellular polymeric substances improved electron transfer and mass transfer among microbes, and higher enzymes (ATPase, NADH and α-Amylase) activities met the physiological demanding of efficient microbial metabolism in biochar-added reactor. Microbiological analysis revealed that biochar-mediated direct interspecies electron transfer (DIET) selectively enriched exoelectrogens (Bacteroides, Proteiniphilum, f_Christensenellaceae, etc.) and acetoclastic Methanosaeta, which contributed to increasing biomethane production. The promoted PAHs biodegradation was mainly dependent on the cooperation between fermenting f_Paludibacteraceae and hydrogenotrophic Methanolinea, and potentially related to biochar-mediated DIET. Metabolic analysis indicated that the metabolic pathways of acetogenesis and methanogenesis were significantly strengthened by biochar, thus alleviating acid inhibition. Also, biochar stimulated functional genes expression in PAHs anaerobic biodegradation. These findings were further verified by a series of short-term metabolism tests.

Application of a manganese dioxide/amine-functionalized metal-organic framework nanocomposite as a bifunctional adsorbent-catalyst for the room-temperature removal of gaseous aromatic hydrocarbons

A high surface area (883 m2·g−1) nanocomposite composed of an amine-functionalized metal–organic framework (NH2-UiO-66 (U6N)) and manganese dioxide (MnO2@U6N) was prepared as bifunctional adsorbent-catalyst for the purification of multiple aromatic volatile organic compounds (VOCs) such as benzene (B), toluene (T), m-xylene (X), and styrene (S), i.e., BTXS. The performance of MnO2@U6N was assessed for BTXS removal both as single- and multi-component systems at room temperature (RT (20 °C)) under dark conditions. MnO2@U6N exhibited superior catalytic-adsorption activity for the RT removal of BTXS. The removal performance of MnO2@U6N against BTXS was then assessed across varying levels of flow rate, VOC concentration, adsorbent/catalyst mass, and relative humidity. To better understand the catalytic-adsorption activity, two types of non-linear kinetic models (pseudo-first-order and pseudo-second-order) were utilized to simulate the experimentally obtained data. In-situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) analysis was also conducted to interpret the removal mechanism of BTXS. Their adsorption capacity (mg·g−1) values are estimated to increase in the order of B (21.1) < T (66.0) < X (79.1) < S (129.7). It is suggested that the adsorbed aromatic VOC molecules on the surface of MnO2@U6N should react with active oxygen species (lattice and adsorbed oxygen) to yield the environmentally benigh end products (i.e., carbon dioxide and water) along with various intermediates (e.g., alkoxides, aldehydes, phenolates, carboxylates, and anhydrides). Accordingly, the VOC removal potential of MnO2@U6N has been validated through the synergistic combination between adsorption (primary process) and catalysis (subordinate process) at RT.

Advantages of residual phenol in coal chemical wastewater as a co-metabolic substrate for naphthalene degradation by microbial electrolysis cell

The use of co-metabolic substrates is effective for polycyclic aromatic hydrocarbons (PAHs) removal, but the potential of the high phenol concentrations in coal chemical wastewater (CCW) as a co-metabolic substrate in microbial electrolysis cell (MEC) has been neglected. In this study, the efficacy of varying phenol concentrations in comparison to simple substrates for degrading naphthalene in MEC under comparable COD has been explored. Results showed that phenol as a co-metabolic substrate outperformed sodium acetate and glucose in facilitating naphthalene degradation efficiency at 50 mg-COD/L. The naphthalene removal efficiency from RP, RA, and RG was found to be 84.11 ± 0.44 %, 73.80 ± 0.27 % and 72.43 ± 0.34 %, respectively. Similarly, phenol not only enhanced microbial biomass more effectively, but also exhibited optimal COD metabolism capacity. The addition of phenol resulted in a stepwise reduction in the molecular weight of naphthalene, whereas sodium acetate and glucose led to more diverse degradation pathways. Some bacteria with the potential ability to degrade PAHs were detected in phenol-added MEC, including Alicycliphilus, Azospira, Stenotrophomonas, Pseudomonas, and Sedimentibacter. Besides, phenol enhanced the expression of ncrA and nmsA genes, leading to more efficient degradation of naphthalene, with ncrA responsible for mediating the reduction of the benzene ring in naphthalene and nmsA closely associated with the decarboxylation of naphthalene. This study provides guidance for the effective co-degradation of PAHs in CCW with MEC, demonstrating the effectiveness of using phenol as a co-substrate relative to simple substrates in the removal of naphthalene.

Gimibacter soli gen. nov. sp. nov., isolated from mangrove soil and insight into its ecological distribution and metabolic potential.

A Gram-stain-negative, facultatively anaerobic, motile and rod-shaped bacterium, designated as 6D33T, was isolated from mangrove soil. Growth was found to occur at 15-32 °C (optimum, 28 °C), at pH 6-9 (optimum, pH 7) and in 0-3 % NaCl (optimum, 1 %, w/v). The results of 16S rRNA gene-based analysis showed that strain 6D33T belonged to the family Temperatibacteraceae, sharing 93.1-94.4 % identity with its close neighbours within the genus Kordiimonas. The phylogenomic results indicated that strain 6D33T formed an independent branch distinct from type strains of the genus Kordiimonas. The overall genome relatedness indices of digital DNA-DNA hybridization, average nucleotide identity and amino acid identity values showed that strain 6D33T represents a novel species of a novel genus. The results of chemotaxonomic characterization indicated that the major cellular fatty acids of strain 6D33T were summed feature 9 (C16 : 0 10-methyl and/or iso-C17 : 1 ω9c), summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) and iso-C15 : 0; the polar lipids comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminolipid and three unidentified lipids; the only respiratory quinone was ubiquinone-10. The genomic size and DNA G+C contents were 3.59 Mbp and 60.84 mol%, respectively. The 16S rRNA gene sequence reads abundance profiles revealed that the rare taxon is prevalent in marine environments, especially in sediments. Genome-scale metabolic reconstruction of strain 6D33T revealed a heterotrophic lifestyle and many pathways responsible for the degradation of aromatic compounds, suggesting application potential in aromatic hydrocarbon removal. Based on its genotypic and phenotypic characteristics, strain 6D33T is concluded to represent a novel species of the novel genus in the family Temperatibacteraceae, for which the name Gimibacter soli gen. nov. sp. nov. is proposed. The type strain of the type species is 6D33T (=GDMCC 1.1959T=KCTC 82335T).

Comparison of exogenous degrader-enhanced bioremediation with low-dose persulfate oxidation for polycyclic aromatic hydrocarbon removal in alkaline soil: efficiency and influence on ecological health

Comparison of exogenous degrader-enhanced bioremediation with low-dose persulfate oxidation for polycyclic aromatic hydrocarbon removal in alkaline soil: efficiency and influence on ecological health

Experimental and mechanistic study of bio-based solvent Cyrene for de-aromatization of model diesel

Liquid-liquid extraction is an important technique for separating aromatic and alkane hydrocarbons. The toxicity and pollution problems of traditional solvents are difficult to solve, and the use of green bio-based solvents for diesel fuel dearomatization is of great significance to solve energy and environmental problems. In this paper, Cyrene, a low toxicity, low cost, green composition bio-based solvent, was selected as an extractant to study its ability to remove mono- and bicyclic aromatics from chain alkanes and cycloalkanes, respectively. In addition to the ternary system, the extraction effects under various experimental conditions and multi-component simulated systems were also investigated. The results showed that aromatics and cyclic structures tend to interact more strongly with Cyrene due to differences in solute structure, and therefore polycyclic aromatic hydrocarbons tend to produce larger distribution coefficients. the selectivity coefficients of Cyrene for the four systems were influenced by differences in interaction energies in the order: dodecane/1-methylnaphthalene > dodecane/indene > decahydronaphthalene/1-methylnaphthalene > decahydronaphthalene/indene. At the same time, multi-component simulated oil experiments have demonstrated that Cyrene is equally selective in removing aromatic hydrocarbons from complex components. Quantum chemical calculations were used to investigate the extraction mechanism of Cyrene. The results of Reduced Density Gradient (RDG), Atoms In Molecules (AIM), and Symmetry-Adapted Perturbation Theory (SAPT) energy decomposition proved that the interaction forces between Cyrene and solute molecules are van der Waals forces dominated by dispersion forces and accompanied by some very weak hydrogen bonds. Finally, thermodynamic correlations using the NRTL model were performed to obtain binary interaction parameters for the four systems. The results of this paper indicate that Cyrene, as a new green bio-based solvent, has the potential to be used as an extractant and shows good separation in the removal of long carbon chain aromatic hydrocarbons, and this paper also provides basic data and references for subsequent studies.

Manganese ore enhanced polycyclic aromatic hydrocarbons removal in constructed wetlands: Insights into the key removal mechanism and main driving factor

Substrates are vital to efficiently remove polycyclic aromatic hydrocarbons (PAHs) in constructed wetlands (CW). However, the critical role of the substrate in the system is still not fully understood due to the unclear PAHs removal mechanism and particularly the main driving factor affecting PAHs removal. In this study, four vertical-flow CWs with different typical substrate types (A: quartz sand, B: quartz sand + granular activated carbon, C: quartz sand + ceramsite, and D: quartz sand + manganese ore) were established to investigate the treatment performance and mechanism of CW systems. Satisfactory and stabilized PAHs removal was achieved in CW-D during the operation period of 120 days, which significantly increased the removal of PAHs by 23.80%–31.18% compared with control group. Microbial degradation was revealed to dominate PAHs removal in CWs, and the enhanced proportion of microbial degradation (21.12%-35.43%) in CW-D led to the higher PAHs removal compared with other CWs. Further analysis showed that altered extracellular polymeric substances and Mn cycle improved the electron transfer capacity, and strengthened the interaction between plants and microorganisms in CW-D. Microbial analysis showed that the abundance of key PAH-degrading microorganisms and microbial metabolic gene expression were enhanced in CW-D, which supported the increased microbial degradation of PAHs. Additionally, root length and microbial diversity were two driving factors affecting PAHs removal rather than specific surface area based on the structural equation modeling analysis. This study provides comprehensive insights into the key role of suitable substrates for PAHs removal as well as the related mechanism and driving factors of PAHs removal in CWs.

Simultaneous Heavy Metal-Polycyclic Aromatic Hydrocarbon Removal by Native Tunisian Fungal Species.

Multi-contamination by organic pollutants and toxic metals is common in anthropogenic and industrial environments. In this study, the five fungal strains Chaetomium jodhpurense (MH667651.1), Chaetomium maderasense (MH665977.1), Paraconiothyrium variabile (MH667653.1), Emmia lacerata, and Phoma betae (MH667655.1), previously isolated in Tunisia, were investigated for the simultaneous removal and detoxification of phenanthrene (PHE) and benzo[a]anthracene (BAA), as well as heavy metals (HMs) (Cu, Zn, Pb and Ag) in Kirk's media. The removal was analysed using HPLC, ultra-high performance liquid chromatography (UHPLC) coupled to a QToF mass spectrometer, transmission electron microscopy, and toxicology was assessed using phytotoxicity (Lepidium sativum seeds) and Microtox® (Allivibrio fisherii) assays. The PHE and BAA degradation rates, in free HMs cultures, reached 78.8% and 70.7%, respectively. However, the addition of HMs considerably affected the BAA degradation rate. The highest degradation rates were associated with the significant production of manganese-peroxidase, lignin peroxidase, and unspecific peroxygenase. The Zn and Cu removal efficacy was considerably higher with live cells than dead cells. Transmission electron microscopy confirmed the involvement of both bioaccumulation and biosorption processes in fungal HM removal. The environmental toxicological assays proved that simultaneous PAH and HM removal was accompanied by detoxification. The metabolites produced during co-treatment were not toxic for plant tissues, and the acute toxicity was reduced. The obtained results indicate that the tested fungi can be applied in the remediation of sites simultaneously contaminated with PAHs and HMs.

Advanced oxidation processes for removal of monocyclic aromatic hydrocarbon from water: Effects of O3/H2O2 and UV/H2O2 treatment on product formation and biological post-treatment

Several oxidative treatment technologies, such as ozonation or Fenton reaction, have been studied and applied to remove monocyclic hydroaromatic carbon from water. Despite decades of application, little seems to be known about formation of transformation products while employing different ozone- or ∙OH-based treatment methods and their fate in biodegradation. In this study, we demonstrate that O3/H2O2 treatment of benzene, toluene, ethylbenzene (BTE), and benzoic acid (BA) leads to less hydroxylated aromatic transformation products compared to UV/H2O2 as reference system – this at a similar ∙OH exposure and parent compound removal efficiency. Aerobic biodegradation tests after oxidation of 0.15 mM BA (12.6 mg C L−1 theoretical DOC) revealed that a less biodegradable DOC fraction > 4 mg C L−1 was formed in both oxidative treatments compared to the BA control. No advantage of ozonation over UV/H2O2 treatment was observed in terms of mineralization capabilities, however, we detected less transformation products after oxidation and biodegradation using high-resolution mass spectrometry. Biodegradation of BA that was not oxidized was more complete with minimal organic residual. Overall, the study provides new insights into the oxidation of monocyclic aromatics and raises questions regarding the biodegradability of oxidation products, which is relevant for several treatment applications.

Water hyacinth derived biochar for polycyclic aromatic hydrocarbons removal and oxidative stress study

Polycyclic aromatic hydrocarbons (PAHs), highly concerned emerging contaminant, are priority persistent organic pollutants (POPs) adversely affect the ecological health of marine sediments. These pollutants have attracted widespread attention because of their potential toxicological effects on aquatic organisms and subsequent threats to human health. In this study, an advanced oxidation process for the remediation of PAH-contaminated sediments was developed by the activation of calcium peroxide (CaO2; CP) using a green catalyst prepared from water hyacinth biochar (WHBC), and the associated biochar-driven cellular oxidative stress was highlighted. The catalytic capacity of WHBC was determined at pyrolysis temperature between 300 and 900 °C. WHBC prepared 700 °C (WHBC700) and CP removed 74% of PAHs from the sediment matrix. Results of antioxidant activity evaluation after exposure to WHBC at doses between 400–4000 and 1000–4000 mg L−1 in human hepatocarcinoma cell lines (HepG2) for 24 h showed enhanced glutathione peroxidase (GPx) and catalase (CAT) activities, respectively. Increase in mRNA levels of superoxide dismutase (SOD) genes was also observed after WHBC exposure (400–4000 mg L−1), implying that the oxidative damage caused by reactive oxygen species (ROS) was inhibited by elevating the cellular antioxidant activity. This study attempted to demonstrate an effective waste-to-resource strategy for remediating PAH-polluted sediment in addition to understanding the potential environmental effects of antioxidant activity and gene expression of carbon-based catalysts on HepG2.

Research Progress on Process-Intensified Water Treatment Applications

Process intensification (PI) is aimed towards essentially smaller, cleaner, safer, energy-efficient sustainable technologies involving the application of a number of strategies, including reducing the number of devices, miniaturization, process integration, improving mass and heat transfer, novel energy and separation techniques and combined optimization and control methodologies. Over the recent years, PI has attracted attention in the domain of aqueous medium adsorptive separations and wastewater treatment as well. Thus far, a limited number of investigations have appeared in the literature; in addition, there is yet a lack of published methods to follow the intensified solutions for processes in wastewater treatment. In this connection, this article aims to present an overview of the recent applications and advances in process-intensified decolorization of dyes; removal of aromatic hydrocarbons from wastewaters; and recovery of proteins, heavy metals and rare earth elements from aqueous media. Selected applications have been identified in terms of the PI techniques, and the corresponding process improvements have been discussed for a variety of examples with the aim of contributing to the future progress of applications. It has been confirmed that considerable process improvements could be possible, such as intensified process efficiency, improved adsorption and separation performance, and minimized sorbent requirement and processing time. Even though there have been considerable developments in the field, there is still a need for further developments for the enhancement of the technologies in adsorption wastewater treatment using a systems approach.

Di- and tri- cyclic aromatic hydrocarbons removal using different prepared materials based Sargassum dentifolium algae, and iron oxide

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are highly toxic and carcinogenic compounds as they are low water solubility, hardly degradable and may persist in the environment for many years. Therefore, this study was directed to PAHs ‘anthracene and naphthalene’ removal using a combination method between adsorption and degradation using sunlight. Three adsorbent materials, iron oxide (Fe) alone, Sargassum dentifolium (S) alone, and mixture of Iron oxide and Sargassum dentifolium (FeS) were prepared. Afterwards, optimisation process was performed for the three adsorbent forms through some preliminary experiments followed by full factorial design experiment to get the optimum interacted factors that achieve high PAHs removal efficiency. Some characterisation analyses such as FT-IR, TEM, DLS, zeta potential, specific surface area, magnetisation analysis, isotherm and kinetics studies were performed. The full factorial design showed that, the highest anthracene removal efficiency of 99.15% was obtained at 50 ppm concentration, 3 h contact time by using 1 g/l Sargassum dentifolium, whereas the highest naphthalene removal efficiency of 93.05% was achieved after 4 h contact time at 50 ppm concentration by using 4 g/l Sargassum dentifolium. Moreover, 93.02% naphthalene removal efficiency was stated at 50 ppm concentration after 1 h contact time by using 1 g/l mixed form of Iron oxide/Sargassum dentifolium.

Removal of Model Aromatic Hydrocarbons from Aqueous Media with a Ferric Sulfate–Lime Softening Coagulant System

The removal of model hydrocarbon oil systems (4-nitrophenol (PNP) and naphthalene) from laboratory water was evaluated using a ferric sulfate and a lime-softening coagulant system. This study addresses the availability of a methodology that documents the removal of BTEX related compounds and optimizes the ferric-based coagulant system in alkaline media. The Box–Behnken design with Response Surface Methodology enabled the optimization of the conditions for the removal (%) of the model compounds for the coagulation process. Three independent variables were considered: coagulant dosage (10–100 mg/L PNP and 30–100 mg/L naphthalene), lime dosage (50–200%), and initial pollutant concentration (1–35 mg/L PNP and 1–25 mg/L naphthalene). The response optimization showed a 28% removal of PNP at optimal conditions: 74.5 mg/L ferric sulfate, 136% lime dosage, and initial PNP concentration of 2 mg/L. The optimal conditions for naphthalene removal were 42 mg/L ferric sulfate, 50% lime dosage, and an initial concentration of naphthalene (16.3 mg/L) to obtain a 90% removal efficiency. The coagulation process was modeled by adsorption isotherms (Langmuir for PNP; Freundlich for Naphthalene). The surface properties of flocs were investigated with pHpzc, solid-state UV absorbance spectra, and optical microscopy to gain insight into the role of adsorption in the ferric coagulation process.