Oil-contaminated Water Research Articles

Multivariate Simultaneous Determination of Some PAHs in Persian Gulf Oil-Contaminated Algae and Water Samples Using Miniaturized Triton X-100-Mediated Fe3O4 Nanoadsorbent and UV-Vis Detection

This research shows the development of a miniaturized solid-phase extraction method with UV-Vis detection for simultaneous determination of dibenzofuran, fluoranthene and phenanthrene using chemometrics approaches. After synthesis of Fe3O4 nanoparticles (Fe3O4 NPs), the surface of the nanoparticles was modified by Triton X100 coating. The influence of extraction solvent and volume, concentration of Triton X100, extraction time, and sample pH were studied and optimized. Due to high spectral overlapping, resolving ternary mixtures for simultaneous determination of targets with classical analytical methods is impossible. Therefore, the recorded UV-Vis spectra were transformed using continuous wavelet transform and then subjected to artificial neural networks (ANNs). The Db4 mother wavelet was used as the better mother wavelet. For simultaneous detection of analytes, a comparison of feed-forward back-propagation and radial basis function networks was accomplished. The calibration graphs showed linearity in the ranges of 2.4–250 ng mL−1, 50–3750 ng mL−1, and 48–5000 ng mL−1 with a limit of detection of 0.58, 9.5 ng mL−1, and 12.5 ng mL−1 under optimal conditions for phenanthrene, fluoranthene, and dibenzofuran, respectively. The limit of quantitation was achieved at 3.52 ng mL−1, 16.35 ng mL−1, and 31.3 ng mL−1 for phenanthrene, fluoranthene and dibenzofuran, respectively. The method involving TX-100-coated Fe3O4 NPs in a liquid sample phase for analyte extraction, followed by ethanol desorption and UV-Vis detection, was successfully applied for the determination of polycyclic aromatic hydrocarbons in oil-field water and algae samples.

Radio- and stable carbon isotope analysis reveals minimal assimilation of petrogenic carbon into an oligotrophic freshwater food web after experimental spills of diluted bitumen

Following an oil spill into water, bacteria can biodegrade petroleum hydrocarbons which could lead to petrogenic carbon assimilation by aquatic biota. We used changes in the isotope ratios of radio- (Δ14C) and stable (δ13C) carbon to examine the potential for assimilation of petrogenic carbon into a freshwater food web following experimental spills of diluted bitumen (dilbit) into a boreal lake in northwestern Ontario, Canada. Different volumes (1.5, 2.9, 5.5, 18, 42, 82, and 180 L) of Cold Lake Winter Blend (a heavy crude blend of bitumen and condensate) dilbit were applied to seven 10-m diameter littoral limnocorrals (approximate volume of 100 m3), and two additional limnocorrals had no added dilbit to serve as controls. Particulate organic matter (POM) and periphyton from oil-treated limnocorrals had lower δ13C (up to 3.2‰ and 2.1‰ for POM and periphyton, respectively) than the control at every sampled interval (3, 6 and 10 weeks for POM and 6, 8 and 10 weeks for periphyton). Dissolved organic and inorganic carbon (DOC and DIC, respectively) had lower Δ14C in the oil-treated limnocorrals relative to the control (up to 122‰ and 440‰ lower, respectively). Giant floater mussel (Pyganodon grandis) housed for 25 days in aquaria containing oil-contaminated water from the limnocorrals did not show significant changes in δ13C values of muscle tissue compared to mussels housed in control water. Overall, the changes in δ13C and Δ14C observed indicated small amounts (up to 11% in DIC) of oil carbon incorporation into the food web. The combined δ13C and Δ14C data provide evidence for minimal incorporation of dilbit into the food web of this oligotrophic lake, suggesting that microbial degradation and subsequent incorporation of oil C into the food web may play a relatively small role in the ultimate fate of oil in this type of ecosystem.

Modified porous membrane with high solar-to-thermal conversion and oil resistance performance for solar steam generation

The utilization of solar steam generator via photothermal conversion is a sustainable and highly sufficient solution for addressing long-standing water scarcity. Due to its extensive optical absorption, dopamine has been considered as a promising photo-thermal conversion material. In this work, by co-depositing Fe3+ and 3-glycidyloxypropyltrimethoxysilane (KH550) with polydopamine (PDA), a high-performance, low-cost, and scalable modified membrane (called PVDF/[email protected]@Fe3+) with superior oil resistance was developed. Under one sun illumination, the resulting PVDF/[email protected]@Fe3+ membrane generated solar steam with a high efficiency of 90.33% and a high evaporation rate of 1.40 kg m−2 h−1. More importantly, the evaporation rate still performs well even in oil-contaminated water due to the improvement of hydrophilicity and anti-fouling capabilities of the modified membrane. In oil-in-water emulsion, the evaporation rate approaches 1.33 kg m−2 h−1 and the evaporation efficiency reaches 85.49%. This study demonstrated that solar steam generation using PVDF/[email protected]@Fe3+ membrane could be a viable option for seawater and oily wastewater purification.

Cost-Effective Natural Adsorbents for Remediation of Oil-Contaminated Water

Oil-contaminated water is among the most significant environmental challenges from various industries and manufacturing processes. Oily water poses a severe environmental threat and is toxic to many forms of life. This study aims to investigate the potential of natural adsorbents, namely animal bones (ABs) and anise residues (ARs), for removing oil from water using a batch adsorption process. The effects of adsorbent dosage (0.2–2 g), oil concentration (200–1000 mg/L), and contact time (30–120 min) on the adsorption process were evaluated. This study is the first to employ ABs and ARs as adsorbents for oil removal, and their efficacy for this purpose has not been previously reported. The results indicate that ABs exhibit superior oil removal capacity compared to ARs. Specifically, ABs removed 45 mg/g of oil from water, while ARs removed only 30 mg/g of oil. Furthermore, ABs achieved a percentage removal rate of 94%, whereas ARs had a percentage removal rate of 70%. The adsorbents were characterised using Fourier transform infrared (FTIR) spectrometry, contact angle measurements before and after adsorption, and thermogravimetric analysis (TGA). In addition to the experimental analysis, several kinetic and adsorption models were employed to investigate the adsorption process. The pseudo-first-order and pseudo-second-order models were used to represent the kinetics of the reaction, while the Langmuir and Freundlich isotherm models were used to represent the adsorption isotherm. Marquardt’s percent standard deviation (MPSD) error function was used to confirm the fit of the experimental data with the isotherm model, in addition to the correlation coefficient R2. The isotherm studies indicated that the experimental data of the two adsorbents used with the Langmuir isotherm model were consistent with one another. The kinetics study demonstrated that the adsorption process using the two adsorbents adheres to a pseudo-second-order kinetics model.

NaOH–ball-milled co-modified magnetic biochar and its oil adsorption properties

A magnetic biochar adsorbent (BM–OH–BC) was prepared through NaOH–ball milling co-modification with walnut shells as the raw material, and its oil adsorption characteristics were investigated. The adsorption properties of oil pollutants were compared before and after the NaOH-ball-milling co-modification, and the mechanism of NaOH-ball-milling on oil pollutants was investigated by scanning electron microscope-energy dispersive X-ray spectroscopy, BET, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The experimental results showed that the oil adsorption capacity of BM–OH–BC can reach 2.75 g/g, which is 129% higher than that of unmodified biochar. Moreover, after five adsorption and desorption cycles, the adsorption rate of BM–OH–BC only decreased by 5.9%, which was because the oil adsorption of BM–OH–BC is mainly chemical adsorption. The adsorption processes involving single layer, heterogeneous phase and multilayer made BM–OH–BC have excellent adsorption properties. After biochar co-modification, the specific surface area of BM–OH–BC increased to 466 m2/g, the total pore volume increased to 0.245 cm3/g, the average pore size decreased to1.90 nm, and the number of hydrophobic non-polar functional groups increased, leading to the enhancement of its oil absorption capacity. This study provides a reference for the treatment of oil-contaminated water bodies.

CO2 improves the anaerobic biodegradation intensity and selectivity of heterocyclic hydrocarbons in heavy oil

Heterocyclic hydrocarbons pollution generated by oil spills and oilfield wastewater discharges threatens the ecological environment and human health. Here we described a strategy that combines the greenhouse gas CO2 reduction with microbial remediation. In the presence of nitrate, CO2 can improve the biodegradation efficiency of the resins and asphaltenes in heavy oil, particularly the biodegradation selectivity of the polar heterocyclic compounds by the newly isolated Klebsiella michiganensis. This strain encoded 80 genes for the xenobiotic biodegradation and metabolism, and can efficiently utilize CO2 when degrading heavy oil. The total abundance of resins and asphaltenes decreased significantly with CO2, from 40.816% to 26.909%, to 28.873% with O2, and to 36.985% with N2. The transcripts per million (TPM) value of accA gene was 57.81 under CO2 condition, while respectively 8.86 and 21.23 under O2 and N2 conditions. Under CO2 condition, the total relative percentage of N1-type heterocyclic compounds was selectively decreased from 32.25% to 22.78%, resulting in the heavy oil viscosity decreased by 46.29%. These results demonstrated a novel anaerobic degradation mechanism that CO2 can promote the anaerobic biodegradation of heterocyclic hydrocarbons in heavy oil, which provides a promising biotreatment technology for the oil-contaminated water.

The effects of nitrogen and phosphorus nutrients on the bioremediation of oil-contaminated waters by Gracilariopsis persica in the coastal areas of Bandar Abbas

This study investigated the influence of nitrogen and phosphorus on the bioremediation of crude oil by Gracilariopsis persica in littoral zone waters. In order to determine the role of nitrogen in bioremediation, urea, ammonium, and nitrate were used with and without phosphorus, with the result that nitrogen had no significant effect on the degradation of oil by Gracilariopsis persica in the littoral zone. Nearly 90 % of the crude oil used in this study was degraded by treatments with added phosphorus and nitrogen. A significant increase in the degradation of oil-contaminated water was observed after the application of phosphorus. Comparatively to the application of phosphorus alone, nitrogen and phosphorus together increased the rate of biodegradation by the algal species. Based on the results of the study, nitrogen and phosphorus have complementary effects on the bioremediation of oil by Gracilariopsis persica.

Scalable and biomimetic anti-oil-fouling photothermal fabric for efficient solar-driven interfacial evaporation

Solar-driven interfacial evaporation (SIE) based on pumping bottom water up to air–water interface for localized heating has raised abundant research interest for clean water production. However, when encountering oil-contaminated water, the oil may block the water transport channels and suppress the water evaporation performance. Here, inspired by the surface structure of mussel, we developed a biomimetic surface coating on a polypyrrole-coated cotton fabric (PGCF) based on the reaction of gallic acid/(3-aminopropyl)triethoxysilane (GA/APTES). GA with the pyrogallol moiety can generate a similar mussel-inspired adhesive coating with the aid of APTES that possesses amino groups mainly through Michael addition/Schiff base reactions. The biomimetic coating with micro- and nano-scale roughness renders the PGCF superhydrophilicity and underwater superoleophobicity, and the obtained flexible fabric showed a stable and efficient water evaporation rate of ∼ 1.54 kg m-2h−1, in pure water and oil-contaminated water including soybean oil, silicone oil, hexadecane, lubricating oil and their mixtures. Moreover, the fabric demonstrates good reusability, and stability against acidic/alkaline/salty environment, providing a simple and easily scalable strategy for the fabrication of flexible SIE fabric for practical use.

Crosslinked biomimetic coating modified stainless-steel-mesh enables completely self-cleaning separation of crude oil/water mixtures

The development of high-flux, durable and completely self-cleaning membranes is highly desired for separation of massive oil/water mixtures. Herein, differently crosslinked poly(2-methacryloyloxylethyl phosphorylcholine) (PMPC) brush grafted stainless steel mesh (SSM) membranes (SSM/PMPCs) were fabricated by integrating of mussel inspired universal adhesion and crosslinking chemistry with surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET-ATRP). The durability and self-cleaning performance of the prepared SSM membranes were evaluated by separating sticky crude oil/water mixtures in a continuous recycling dead-end filtration device. The water filtration flux driven by gravity reached 60,000 L⋅m−2⋅h−1 with a separation efficiency of over 99.98%. Furthermore, zero-flux-decline was observed during a 5 h continuous filtration when assisted by mechanical stirring. More significantly, such a completely self-cleaning separation of the well crosslinked SSM/PMPC2 membrane under optimized flux and stirring conditions had been operated cumulatively for 190 h in 30 days without any additional cleaning. These significant advances are more promising for practical applications in crude oil-contaminated water treatments and massive oil/water mixture separation.

Technology Focus: Oilfield Chemistry (September 2022)

The technical arena of oilfield chemistry is no longer an area of interest only to production operations. When completions operations (including hydraulic fracturing) yield wells with a low productivity index (PI), all chemical constituents introduced downhole (e.g., drilling, completions, and stimulation) are scrutinized for deleterious interactions with the mineralogy, formation fluids, and one another. Field-relevant work flows and improved test methods are critical to the investigation of root causes for a low PI. Several studies have been published showcasing new additives and fluids that can improve well productivity. However, often the methods to select and optimize these products do not account for the uncertainties and challenges of an actual wellsite (e.g., sample collection and integrity, challenging surface conditions, and representative samples). Operators must challenge themselves first to document and rank the most likely causes of low or declining well productivity using actual well samples and parameters. Then, collaboration with chemical and service providers is used to technically justify (a) the selection and optimization of chemical additives to maintain or stimulate productivity on existing producers and (b) the optimization of additives for future well completions in the same reservoir. The selected papers represent sophisticated work around the phenomena of scale and precipitation that can have dramatic effects on productivity, specifically in shale and tight completions. These papers include comprehensive work flows to analyze recovered samples (to confirm damage identification) as well as improved methods to analyze the concentration of scale inhibitor in produced water with enhanced simplicity and accuracy. The selections also include integrated studies of the phenomena of chemical species at critical interfaces (formation, cement, and casing) that can seed production of damaging deposits, with an eye toward prevention of their effects on productivity. Recommended additional reading at OnePetro: www.onepetro.org. SPE 205284 Surfactant and Friction-Reducer Interaction in High-Salinity Slickwater Fracturing by Abdelrahman Kotb, Texas A&M University, et al. SPE 209507 The Oda Field: From Scale Prediction to Reality—Why Squeezing Was Not Necessary Despite a High Calcium Sulphate Risk by Baard Kaasa, Scale Consult, et al. URTeC 208302 A Flexible Biomimetic Superhydrophobic and Superoleophilic 3D Macroporous Polymer-Based Robust Network for the Efficient Separation of Oil-Contaminated Water by Fahd I. Alghunaimi, Saudi Aramco, et al.

Evaluation of di-rhamnolipid biosurfactants production by a novel Pseudomonas sp. S1WB: Optimization, characterization and effect on petroleum-hydrocarbon degradation

Rhamnolipid biosurfactants are multifunctional compounds that can play an indispensable role in biotechnological, biomedical, and environmental bioremediation-related fields, and have attracted significant attention in recent years. Herein, a novel strain Pseudomonas sp. S1WB was isolated from an oil-contaminated water sample. The biosurfactants produced by this strain have capabilities to reduce surface tension (SFT) at 32.75 ± 1.63 mN/m and emulsified 50.2 ± 1.13 % in liquid media containing 1 % used engine oil (UEO) as the sole carbon source. However, the lowest SFT reduction (28.25 ± 0.21), highest emulsification index (60.15 ± 0.07), and the maximum yields (900 mg/L) were achieved under optimized conditions; where, the glucose/urea and glycerol/urea combinations were found efficient carbon and nitrogen substrates for improved biosurfactants production. Biosurfactants product was characterized using ultra-high performance liquid chromatography-mass spectrometry (UHPLC- MS) and detected various di- rhamnolipids congeners. In addition, the di-rhamnolipids produced by S1WB strain was found highly stable in terms of surface activity and EI indices at different environmental factors i.e. temperature, pH and various NaCl concentrations, where, emulsifying property was found high stable till 30 days of incubation. Moreover, the stain was capable to degrade hydrocarbon at 42.2 ± 0.04 %, and the Gas chromatography- mass spectrometry (GC-MS) profile showed the majority of peak intensities of hydrocarbons have been completely degraded compared to control.

Ecotoxicity Studies for On-Site Disposal of Decant Water During Oil Spills: A Review

Mechanical oil recovery, a most used tool for oil spill response, can generate a considerable proportion of oil-contaminated water (10–70%). Large storage space is commonly required to transport the recovered oil and water mixture to shore. Transit and transportation consume loads of time, money, and resources while reducing oil recovery’s overall efficiency and capacity. Techniques of on-site treatment and disposal of oily wastewater provide benefits for oil recovery by freeing storage space. However, the high petroleum content of decant water can lead to uncertain risks, if discharged into the marine ecosystem. Insufficient ecological toxicity data and research limit the standardization and establishment of regulative tools. To fill the knowledge gaps, this review comprehensively summarized recent studies on the potential impacts of the organic composition in decant water, including oil–water accommodated fractions, dispersed oil droplets, and other related chemicals, on various marine species (i.e., bacterium, invertebrates, fishes, plants, reptiles, and mammals). The toxicity effects and the ecological endpoints of oils, TPH, and PAHs on different species were discussed. Recommendations for future ecological impacts and decant water composition were provided to support the on-site disposal of the water fraction.

A comparative study on modification of aerogel-based biosorbents from coconut fibers for treatment of dye- and oil-contaminated water

In this study, the discarded coconut fibers are treated with sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) to recover the purified cellulose for further being transformed into the cellulose-based aerogels without consuming and releasing any toxic chemicals. This work also provides a comparison between two methods of synthesizing the cellulose aerogels via using physical cross-linkers polyvinyl alcohol/xanthan gum (PVA/XTG), the alkali-urea method and carbonization in terms of characteristics, dye removal, oil adsorption as well as simplicity and feasibility of the synthesis determined by the material balance of cellulose recovery and aerogel fabrication. Overall, the fabricated aerogels maintain a high porosity of 96.30–98.32%, low density of 0.034–0.063 g/cm3, and outstanding adsorption capacity for methylene blue (MB) and oil. It is worth noting that the carbon aerogels exhibit an impressive maximum MB adsorption capacity of 625 mg/g which is three times higher than that of the uncarbonized aerogels. Without modification, the carbon aerogels show the highest oil sorption capacity of 22.71 g/g among the investigated subjects. The results demonstrate that our aerogels are all promising candidates for the treatment of contaminated wastewater.

Production of biosurfactant by Bacillus megaterium and its correlation with lipid peroxidation of Lactuca sativa

The biosurfactant-producing bacterial isolate was isolated from an oil-contaminated water sample. This study aimed to determine the production of biosurfactant and its effect on the plant growth via the biosorption of some heavy metals. The isolate was identified by 16S rRNA gene sequence analysis as Bacillus megaterium ATTC 14581. The surface activity of the produced biosurfactant was determined. The biosurfactant was recovered from the cell-free culture of a bacterial strain at 1.5 g/L. The extracted biosurfactant shows potential stability towards some factors, like temperature and salinity. The FTIR analysis confirmed the production of surfactin biosurfactant. The impact of B. megaterium biosurfactant on Pb and Ar significantly increases morphological features, proline, and antioxidant enzymes, while a significant decrease in lipid peroxidation, H2O2, and O2.

Evaluation of water quality and ecological risk assessment index from highly oil-contaminated sites in the Niger Delta Nigeria

Multi-element indices in an aquatic ecosystem provide insight into the synergistic effects of many ecological parameters. Using standard analytical techniques and pollution indicators, the eco-toxicological state of oil-contaminated water in three communities in Warri Southwest, Niger Delta, Nigeria, was assessed. Water samples were examined for physicochemical properties, heavy metals, PAH and TPH levels. The ANOVA results showed no significant difference (p >0.05) between the means of the physicochemical parameters and the study stations for the combined parameters. Out of the twenty-five parameters evaluated, the Nemerow Pollution Index (NPI) results revealed thirteen contributing parameters to overall water contamination in the research areas. Conductivity, TSS, TDS, DO, BOD, COD, Oil and Grease, Heavy Metals (Cu, Ni, Mn, and Cd), and Hydrocarbons are among them. These parameters also exceeded the maximum permitted limits set by NESREA. Heavy metal evaluation index (HEI) and geo-accumulation index (Igeo) in water were both found to be high. The PERI (potential ecological risk index) had values >100, indicating a high level of ecological risks. The study areas' overall water quality index (WQI) indicated poor to unsuitable water quality. Water pollution in the selected communities is attributed to various industrial and domestic activities along the waterways, crude oil spills, illegal refining, dredging, and ship and speed boat movement. Periodic monitoring and preventive measures are required in the study areas to keep the aquatic ecosystems from entirely degrading. Adequate legislation and proper effluent management could aid in the prevention of indiscriminate toxic compound discharge into water.

L-lysine functionalized Ti3C2Tx coated polyurethane sponge for high-throughput oil–water separation

Creating an efficient method that can provide simple, practical and high-throughput separation of oil–water mixtures has proved extremely challenging. Two-dimensional layered Ti3C2Tx MXene material with excellent hydrophilicity has attracted substantial attention for oil–water separation. However, conventional Ti3C2Tx separation membranes are susceptible to contamination by oil due to its relatively high adhesion to oil, hindering its practical applications in high-efficiency oil–water separation. To make Ti3C2Tx have underwater superoleophobicity and low oil adhesion, the surface of Ti3C2Tx can be modified by introducing hydrophilic groups. Herein, L-lysine functionalized Ti3C2Tx (Ti3C2Tx-Ly) was firstly prepared by decorating L-lysine on Ti3C2Tx through electrostatic interaction and hydrogen bonding. A facile dip-coating method is then used to coat polyurethane (PU) sponge with Ti3C2Tx-Ly, obtaining a superhydrophilic/underwater superoleophobic Ti3C2Tx-Ly @PU sponge. Owing to the excellent underwater superoleophobicity resulting from hydrophilic groups (–OH、–NH3) on the surface of Ti3C2Tx-Ly nanosheets and the enlarged interlayer spacing of Ti3C2Tx, the Ti3C2Tx-Ly @PU sponges demonstrated outstanding separation performance for a series of oil–water mixtures. Specifically, the Ti3C2Tx-Ly @PU sponge exhibits low oil adhesion and superhydrophilic (WCA = 0°)/submerged superoleophobic (UOCA > 155°) properties. The Ti3C2Tx-Ly @PU sponges displayed the best separation performance for cyclohexane/water mixture, and the maximum permeation flux is up to 221892 L m–2 h–1, accompanied by a remarkable separation efficiency of higher than 99.2% after 100 cycles. The permeation flux has exceeded most of the previous reported multifunctional separation membranes. In addition, the Ti3C2Tx-Ly @PU sponge also showed excellent separation performance for high-density oil dichloromethane/water with a separation efficiency over 99.4%. Of note, the Ti3C2Tx-Ly @PU sponge features excellent chemical stability to corrosive media, such as acidic, alkaline, and high salt solutions, possessing great potential for real-world applications. Furthermore, the as-prepared Ti3C2Tx-Ly @PU sponge exhibits rapid and efficient separation of oil-water mixtures through a fully gravity-driven process, which makes it a good candidate for industrial oil-contaminated water treatment and oil spill clean-up, and also provides new insights into the design and development of functional Ti3C2Tx through L-lysine modification. Therefore, this work reports a facile and promising way to fabricate scalable superhydrophilic/underwater superoleophobic sponge material for highly efficient oil–water separation.

Emulsion templated dual crosslinked core-sheath fibrous matrices for efficient oil/water separation

Oil-contaminated water and its purification is a major challenge and efforts in this direction have accumulated immensely over past decades as the depletion of freshwater resources is also seen in parallel. Electrospun fibrous matrices used for this purpose offer several attractive features including porous nature, high surface area, ease of fabrication and functionalization. However, poor mechanical strength and separation capacity of electrospun matrices have restricted their use. In this report, fabrication of robust, dual crosslinked fibrous matrices via emulsion electrospinning is presented. A unique near-gel resin based oil-in-water emulsion was developed as the precursor for electrospinning. Fibres had uniform core-sheath morphology formed by crosslinked polystyrene as core and crosslinked polyvinyl alcohol as sheath, thereby having distinct domains to selectively adsorb oil and water. Post-electrospinning crosslinking was optimized to achieve matrices of excellent dimensional stability, selective wettability, and hydration ability. The dual crosslinked structure of the nanofibres was responsible for not only high oil adsorption (≈ 3305%) but also efficient oil/water emulsion separation with 99% separation efficiency and a flux up to 3000 L m−2 h−1. The matrices were successfully used up to 10 separation cycles without any structural disintegration or decline in separation performance, thereby reflecting their suitability for oil/water separation.

Bioaugmentation-Enhanced Remediation of Crude Oil Polluted Water in Pilot-Scale Floating Treatment Wetlands

Floating treatment wetlands (FTWs) are cost-effective systems for the remediation of polluted water. In FTWs, the metabolic activity of microorganisms associated with plants is fundamental to treatment efficiency. Bioaugmentation, the addition of microorganisms with pollutant-degrading capabilities, appears to be a promising means to enhance the treatment efficiency of FTWs. Here, we quantified the effect of bioaugmentation with a four-membered bacterial consortium on the remediation of water contaminated with crude oil in pilot-scale FTWs planted with Phragmites australis or Typha domingensis. The bacteria had been isolated from the endosphere and rhizosphere of various plants and carry the alkane hydroxylase gene, alkB, involved in aerobic hydrocarbon degradation. During a treatment period of 36 days, FTWs planted with P. australis achieved a reduction in hydrocarbon concentration from 300 mg/L to 16 mg/L with and 56 mg/L without bioaugmentation. In the FTWs planted with T. domingensis, respective hydrocarbon concentrations were 46 mg/L and 84 mg/L. The inoculated bacteria proliferated in the rhizoplane and in the plant interior. Copy numbers of the alkB gene and its mRNA increased over time in plant-associated samples, suggesting increased bacterial hydrocarbon degradation. The results show that bioaugmentation improved the treatment of oil-contaminated water in FTWs by at least a factor of two, indicating that the performance of full-scale systems can be improved at only small costs.

Treatment of motor oil-contaminated water via sorption onto natural organic lignocellulosic waste: thermodynamics, kinetics, isotherm, recycling, and reuse

Treatment of motor oil-contaminated water via sorption onto natural organic lignocellulosic waste: thermodynamics, kinetics, isotherm, recycling, and reuse

Sprayable, durable, and superhydrophobic coating of silica particle brushes based on octadecyl bonding and polymer grafting via surface-initiated ATRP for efficient oil/water separation

A facile approach to prepare sprayable, durable, and superhydrophobic coating was designed for highly efficient oil/water separation and oil absorption based on silica particle brushes via surface-initiated (SI-ATRP). Octadecyl group bonded and poly(styrene-co-acrylonitrile) (PSAN) grafted silica nanoparticles (NPs) (C18-SiO2-g-PSAN) were prepared by sequential initiator tethering and SI-ATRP processes, which were directly applied as surface superhydrophobic coating for various porous substrates. The results confirmed that octadecyl group and PSAN were successfully bonded on silica NPs. After facile spraying of C18-SiO2-g-PSAN, the coated porous substrates displayed superhydrophobicity with an advancing water contact angle (WCA) exceeding 150° due to the synergistic effects of low surface energy compositions contributed by the tethered octadecyl group and the rough structure induced by silica NPs and porous substrates. Superhydrophobic porous substrates exhibited high oil/water separation efficiency achieving 98.8% by using cotton fabric as substrate and remarkable oil absorption capacity of 39.2 g/g for isooctane using polyurethane sponge as substrate. The recyclability and strong durability against mechanical abrasion enable them to be promising candidates for industrial oil-contaminated water treatments and marine spilt oil cleanup in harsh environments.