Initial Total Petroleum Hydrocarbon Research Articles

Enhancing in situ remediation of clayey soils contaminated with total petroleum hydrocarbons by combining pneumatic fracturing, plasma blasting, and vacuum extraction: A comprehensive field investigation

Oxidant injection technology is widely used in soil remediation; however, subsurface conditions, including soil properties and permeability, significantly influence its effectiveness. In this study, the potential of the combination of pneumatic fracturing, plasma discharge, and vacuum extraction (PPV) in enhancing soil permeability and remediating field-scale silt/clayey soils contaminated by total petroleum hydrocarbon (TPH) was studied. Improved soil permeability was assessed by measuring the chlorine and H2O2 concentrations in soil samples, and the remediation efficiency of PPV was evaluated by analyzing the TPH concentrations in the soil samples. The initial highest TPH concentration was 6,922mgkg-1; after a 42-day operation period, the TPH levels decreased to 541mgkg-1. The economic assessment of PPV revealed it to be cost-effective, with a total operating cost of US$ 3,077 for remediating 265m³ of contaminated soil, equating to US$ 11.6 per ton of soil. Since PPV requires a short operational period, is inexpensive, and is suitable for purifying low-permeability soil, it is a promising and economically advantageous approach for soil purification. Overall, PPV demonstrated the ability to enhance oxidizing agent transfer by increasing soil permeability, suggesting its potential for efficient and targeted soil remediation.

Activation of persulfate by g-C3N4/nZVI@SBC for degradation of total petroleum hydrocarbon in groundwater

In this study, we synthesized a high removal efficiency catalyst using biochar-supported nanoscale zero-valent iron and g-C3N4, denoted as g-C3N4/nZVI@SBC, to activate persulfate (PS) for the degradation of total petroleum hydrocarbon (TPH) in groundwater. We characterized the morphology and physiochemical properties of g-C3N4/nZVI@SBC with scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), BET surface area analysis, and X-ray photoelectron spectroscopy (XPS). To assess the performance of the g-C3N4/nZVI@SBC catalyst, we investigated various reaction parameters, such as the mass ratio of g-C3N4 to nZVI@SBC, PS concentration, initial pH, initial TPH concentration, and the presence of coexisting ions in the system. The results from batch experiments and repeated use trials indicate that g-C3N4/nZVI@SBC exhibited both excellent catalytic activation capability and impressive durability, making it a promising choice for TPH degradation. Specifically, when the PS concentration reached 1 mM, the catalyst dosage was 0.3 g/L, and the g-C3N4 to nZVI@SBC mass ratio was 2, we achieved a remarkable TPH removal efficiency of 93.8%. Through electron paramagnetic resonance (EPR) testing and quenching experiments, we identified sulfate radicals, hydroxyl radicals, and superoxide radicals as the primary active substance involved in the TPH degradation process. Moreover, the g-C3N4/nZVI@SBC composite proved highly effective for in-situ TPH removal from groundwater and displayed an 86% removal rate, making it a valuable candidate for applications in permeable reactive barriers (PRB) aimed at enhancing environmental remediation. In summary, by skillfully utilizing g-C3N4/nZVI@SBC, this study has made notable advancements in synthesis and characterization, presenting a feasible and innovative approach to addressing TPH pollution in groundwater.

Evaluation of the potentials of <i>Pennisetium glaucum</i> and <i>Vigna unguiculata</i> for phytoremediation of Spent-engine oil contaminated soil

One promising technique for cleaning up soil polluted by spent engine oil is phytoremediation. Particularly in the tropics, where resources can be scarce and the climate is favorable for plant development. Finding plant species that will work well with this technology was the aim of this investigation. The ability of a cereal (Pennisetum glaucum) and a legume (Vigna unguiculata) to remediate soil contaminated with 1%, 2%, 3%, 4%, and 5% (W/V) of spent engine oil was evaluated. After 150 days of incubation, the Total Petroleum Hydrocarbon (TPH) loss in greenhouse studies was calculated. The total petroleum hydrocarbon content of soil that was vegetated with P. glaucum and V. unguiculata was substantially lower than that of non-vegetated soil. Furthermore, a positive association was discovered between the initial TPH and the total petroleum hydrocarbon loss caused by planting P. glaucum. It was also discovered that P. glaucum outperformed V. unguiculata in remediation capacity. These findings suggest that P. glaucum be investigated further, which might lead to a better understanding of how to apply phytoremediation to soils contaminated with spent-engine oil.

Remediation of spent engine oil-contaminated soil through biostimulation and bioaugmentation with sodium dodecyl sulphate (SDS) and indigenous hydrocarbonoclastic bacterial isolates.

Pollution caused by spent engine oil has become a major global ecological concern as it constitutes a big threat to plants, animals, microorganisms and the soil ecosystem. This study was undertaken to examine the remediation of spent engine oil-contaminated soil through biostimulation and bioaugmentation with sodium dodecyl sulphate and indigenous hydrocarbonoclastic bacterial isolates. Twelve mesocosms were organized into four groups designated G1, G2, G3 and G4 and each filled with 2.5kg of soil samples. Each group was composed of three mesocosms to produce a triplicate setup. G1 contained pristine soil which served as a positive control. G2 contained a total petroleum hydrocarbon (TPH) of 913.333mg/kg in the untreated oil-polluted soil which served as a negative control. G3 contained a TPH of 913.333mg/kg in the polluted soil inoculated with indigenous hydrocarbonoclastic bacterial isolates. G4 contained a TPH of 913.333mg/kg in the polluted soil mixed with bacterial consortium and sodium dodecyl sulphate. The level of pollution was 36.5% in the triplicate setup G2, G3 and G4. Fourier Transform Infrared spectroscopy was used to determine the degree of hydrocarbon degradation. The initial TPH value of 913.33mg/kg was reduced by 84.44% (142mg/kg) in soil inoculated with indigenous hydrocarbonoclastic bacterial isolates and by 88.28% (106.66mg/kg) in biostimulated soil. Result of this study show that soil stimulation involving bacterial consortium and sodium dodecyl sulphate was more efficient than bioaugmentation strategy alone used in the remediation of spent engine oil-polluted soil.

Demonstration of a scalable process for remediation of petroleum-impacted soil using electron beam irradiation

Petroleum-impacted soils pose several hazards and require fast, effective, and versatile remediation techniques. Electron beam irradiation provides a novel means of heating soil and inducing non-equilibrium chemical reactions and has previously been applied to environmental remediation. In this work a scalable process for remediation of petroleum-impacted soils using a 100 kW, 3 MeV industrial electron beam is investigated. The process involves conveying impacted soil through a beam at a controllable rate to achieve a desired dose of approximately 1000 kGy. Reductions to less than 1% Total Petroleum Hydrocarbon (TPH) content from an initial TPH of 3.3% were demonstrated for doses of 710–1370 kGy. These reductions were achieved in in conditions equivalent to 4 m3 per hour, demonstrating the applicability of this technique to remediation sites. TPH reduction appeared to be temperature-dependent but not heavily dependent on dose rate, with reductions of 96% achieved for a dose of 1370 kGy and peak temperature of 540 °C. The performance of the process at high dose rates suggests that it can be incorporated into remediation of sites for which a high rate of material processing is required with a relatively small device footprint.

Adsorption of total petroleum hydrocarbon in groundwater by KOH-activated biochar loaded double surfactant-modified nZVI

Introduction: Crude oil and petroleum hydrocarbon contamination is commonly found in the soil and groundwater during the various processes of mining, processing, and utilization due to issues such as inefficient environmental management, random wastewater discharge, and storage tank leakage.To address this issue, we will use corn stalk biochar (SBC) and surfactants to improve the stability and chemical reactivity of nZVI, thereby enhancing its ability to remove pollutants, and explore the adsorption effect and mechanism of composite materials for petroleum hydrocarbons.Methods: Modified corn stalk biochar (SBC) was synthesized through high-temperature carbonization and KOH activation. Subsequently, the iron/carbon composite PN-nZVI@SBC (PNMSBC) was prepared by loading nano zero-valent iron modified with dual surfactants, and it was adopted to adsorb total petroleum hydrocarbons(TPH) in groundwater. The physical and chemical properties, surface patterns, and elemental mapping of PNMSBC particles were analyzed using SEM, EDS, TEM,XRD, BET, and FTIR spectroscopy. Kinetics and isotherm tests were performed to evaluate the adsorption properties of the composites. TPH adsorption was dependent on ionic strength, initial TPH concentration, as well as pH. The adsorption mechanism combining XPS and EPR spectroscopy was explored.Results: The characterization results by SEM and TEM showed that the particle size of nZVI particles modified by surfactants became smaller, and the dispersibility was enhanced. The characterization results by XRD and FTIR confirmed the successful preparation of the composites. The BET results showed that MSBC and PNMSBC were mesoporous structures. The characterization results indicated that Polyvinylpyrrolidone (PVP) and Sodium oleate (NaOA) inhibited the oxidation of nZVI while effectively improving its reactivity. The result of the experiments on adsorption showed that the removal of TPH by PNMSBC followed Freundlich isotherm and pseudo-second-order kinetic models, thus suggesting that the main adsorption processes comprise chemisorption and multilayer heterogeneous adsorption. The adsorption capacity of PNMSBC was increased by the abundance of macro and microporous structures. To be specific, a maximum Langmuir adsorption capacity (qm) was achieved as 75.26 g/g. The result of batch experiments indicated that PNMSBC continuously removed considerable TPH under a wide pH range from 2 to 6. The adsorption mechanism of PNMSBC includes surface adsorption, oxidation, complexation, and electrostatic interaction.Discussion: In brief, PNMSBC has a promising application for the adsorption of TPH in groundwater remediation.

Biodegradation of Petroleum Sludge by Methylobacterium sp. Strain ZASH.

A bacterium was isolated from sludge-contaminated soil in a petroleum refinery and tested for its ability to degrade aliphatic hydrocarbon compounds present in petroleum sludge. The isolate was grown on minimal salt media agar supplemented with 1% (w/v) petroleum sludge. The isolate was tentatively identified as Methylobacterium s p. s t rain ZASH based on the partial 16s rDNA molecular phylogeny. The bacterium grew optimally between the temperatures of 30°C and 35°C, pH 7 and 7.5, 0.5% and 1.5% (v/v) Tween 80 as the surfactant, and between 1% and 2% (w/v) peptone as the nitrogen source. The constants derived from the Haldane equation were μmax = 0.039 hr-1, Ks = 0.385% (w/v) total petroleum hydrocarbons (TPH) or 3,850 mg/L TPH, and Ki =1.12% (w/v) TPH or 11,200 mg/L. The maximum biodegradation rate exhibited by this strain was 19 mg/L/hr at an initial TPH concentration of 10,000 mg/L. Gas chromatography analysis revealed that after 15 days the strain was able to degrade all aliphatic n-alkanes investigated with different efficiencies. Shorter n-alkanes were generally degraded more rapidly than longer n-alkanes with 90% removal for C-12 compared to only 30% removal for C-36. The addition of sawdust did not improve bacterial degradation of petroleum hydrocarbons, but it assisted in the removal of remaining undegraded hydrocarbons through adsorption.

Ribosomal RNA gene operon copy number, a functional trait indicating the hydrocarbon degradation level of bacterial communities

The lack of universal indicators for predicting microbial biodegradation potential and assessing remediation effects limits the generalization of bioremediation. The community-level ribosomal RNA gene operon (rrn) copy number, an important functional trait, has the potential to serve as a key indicator of the bioremediation of organic pollutants. A meta-analysis based on 1275 samples from 26 hydrocarbon-related studies revealed a positive relationship between the microbial hydrocarbon biodegradation level and the community-level rrn copy number in soil, seawater and culture. Subsequently, a microcosm experiment was performed to decipher the community-level rrn copy number response mechanism during total petroleum hydrocarbon (TPH) biodegradation. The treatment combining straw with resuscitation-promoting factor (Rpf) exhibited the highest community-level rrn copy number and the most effective biodegradation compared with other treatments, and the initial TPH content (20,000 mg kg-1) was reduced by 67.67% after 77 days of incubation. TPH biodegradation rate was positively correlated with the average community-level rrn copy number (p = 0.001, R2 = 0.5781). Both meta and community analyses showed that rrn copy number may reflect the potential of hydrocarbon degradation and microbial dormancy. Our findings provide insight into the applicability of the community-level rrn copy number to assess bacterial biodegradation for pollution remediation.

Electron beam remediation of soils impacted with heavy hydrocarbons

During electron beam (EBeam) irradiation, high-energy electrons can generate physical and chemical changes in a substance such as chain scission and cross-linking. Irradiation of soil is shown to be an effective technology for rapid reduction of Total Petroleum Hydrocarbons (TPH) in crude oil impacted soils. An experimental apparatus for batch treatment of 100 g soil samples was built and tested using a 10 MeV, 15 kW electron beam. The samples were a variety of crude oil impacted soil samples with TPH contents ranging between 1.6 and 32% by mass. Soils of initial TPH up to 9.1% (dry weight basis) TPH levels were reduced to below a target cleanup level of 1% with irradiation doses ranging from 700 kJ/kg to 1100 kJ/kg and treatment times less than 200 s, with maximum soil temperatures less than 450 °C. Soils with elevated moisture content required higher dosages or preliminary drying. EBeam treatments resulted in 1) reduction for both light and heavy hydrocarbon, 2) generation of new light hydrocarbons, and 3) generation of fixed carbon, indicating that the mechanisms of electron beam remediation include radical induced reactions at relatively low temperature and relatively short time scales and not simply thermal desorption effects.

Bench-Scale Biopile Hydrocarbons Removal Optimization Using the Response Surface Methodology and Simultaneous Optimization

Nowadays, the generation of vast volumes of oily sludges is associated with industrial operations such as production, pretreatment, processing, water separation, and storage tank maintenance. Biopiles can be more efficient than other techniques for removing hydrocarbons in sludges, but their removal efficiency depends on operating variables. The goal of this study was to determine the best operating variable ranges at the bench scale to simultaneously optimize hydrocarbons removal in a biopile prototype. This research was conducted within the framework of a Cuban project and used an experimental protocol that integrates several standardized methods and engineering procedures into a series of steps. A Box-Behnken design was implemented for three factors and two response variables: the mass of Total Petroleum Hydrocarbons (TPH) removed and the final concentration of TPH. A simultaneous optimum was obtained for an initial TPH concentration of 39 278 mg·kg-1 and contents of texturizer and moisture of 6,45 and 25,95%, respectively. The obtained variable ranges ensure a compromise solution that maximizes the mass of TPH removed and keeps the contaminant concentration under the Cuban disposal regulations. The results have been used to set up the biopiles at a pilot scale as a subsequent stage of the project.

Remediation of Lubricant Contaminated Soils by Cavitation Microjet Shock Wave Soil Washing System with Ozonation

ABSTRACT Adopting soil washing to clean up petroleum hydrocarbon contaminated soils with high sand content is considered as a fast and economical method. Cavitation microjet shock wave soil washing system (CMS) enhanced by the use of ozonation was developed for remediation of aged lubricant contaminated soil in this study. Contaminated soil with total petroleum hydrocarbon (TPH) ranging from 1890 mg/kg to 15735 mg/kg were applicable for CMS soil washing system. The impacts of factors including initial TPH concentration hydrocarbon (TPH) concentration, soil particle size, soil washing time, and ozone treatment time onto soil washing were investigated through a 21-month period of field operation. The contaminated soils with particle size between 0.074 mm and 0.25 mm, mainly very fine sand and find sand, demonstrated 31% to 98% of TPH removal by air-injected CMS and 19% to 92% of TPH removal by CMS with ozone addition. The optimal cavitation washing time was 20 minutes. The study indicated that optimal ozone concentration in the slurry was 1.08 mg/L which require air of 27 L/min for ozone produced. However, given the short contact time in the CMS system, ozone addition in the slurry did not improve TPH removal effectively. Considering the compatible TPH removal efficiency and energy cost of ozone addition in the soil washing system, use of air-injected CMS soil washing system may be considered as an alternative way.

Predictive comparison and assessment of ANFIS and ANN, as efficient tools in modeling degradation of total petroleum hydrocarbon (TPH)

Composting is an effective organic waste management practice with a sustainable environmental impact on soil. In most cases, composting materials are agricultural residues constituting a huge environmental challenge. This study investigates the composting biostimulation of total petroleum hydrocarbon (TPH) contaminated soil using organic compost prepared from palm oil mill effluent (CPOME). The performance of CPOME in TPH degradation was evaluated using the first-order kinetic model and CO₂ evolution. The artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) modelling approaches were further employed to optimize the experimental response. The experimental designs for ANFIS and ANN modelling were done using the central composite design (CCD). Statistical parameters such as RMSE, MSE, and MAE were used to evaluate model performance and comparisons. The first-order kinetic model and CO₂ released showed that TPH degradation favours contaminated soil with 40 g/L initial TPH concentration. The first-order kinetic model observed a decrease in the constant degradation rate with increasing TPH concentration. The CO₂ evolution, which measures microbial respiration/activity, also showed a decline in released CO₂ with increasing TPH concentration. Lower values of RMSE, MSE, and MAE were obtained for the ANFIS model compared with the ANN. The R² values between the experimental and model-predicted responses showed that the ANFIS (0.9349) model predictions fitted adequately compared to the ANN (0.8862). Finally, comparison and model performances showed that the ANFIS model prediction capability was considerably better than the ANN. • The compost from palm oil mill effluent proved effective in TPH degradation • ANFIS predicted TPH degradation was better than the ANN predicted • Notable organic materials in the compost includes polysaccharides, nitrogen and lignin

Reduction of the soil environmental impact caused by the presence of total petroleum hydrocarbons (TPH) by using Pseudomonas sp.

This research focuses on the bioaugmentation with Pseudomonas sp. (native) and Pseudomonas aeruginosa (commercial) for the biodegradation of total petroleum hydrocarbons (TPH) of the environmental soil samples of the AqLab laboratory in Orellana, Ecuador. Two treatments of sterilized soil (one inoculated with the native strain and the other inoculated with the commercial strain), where used for physical- -chemical analyzes as well as the degradation of TPH. They were evaluated every 20 days for a total period of 80–100 days. The native bacterium was isolated from the laboratory agglomerates in a selective culture medium specific for Pseudomonas sp. The biodegradation of the TPH exhibited a positive result after 80 and 100 days of treatment, with a reduction of 84 and 96% of initial TPH after the bacterial inoculation. The comparison between the two strains evaluated, commercial and native, showed a greater efficiency of biodegradation by the native strain isolated directly from the agglomerates, suggesting working with native strains of the place that have a greater adaptability to the contaminated environment that would ensure bioremediation processes faster and more efficient, low cost and environmentally friendly.

Physicochemical Indices of Phyto Remediated Hydrocarbon Polluted Soil and the Effect of Bio-nutrient Amendment

Aim: To assess the Physicochemical indices of Phytoremediated Crude Oil polluted amended soil using grass plant Cyperus esculentus (Cyp) and Phyllanthus amarus (Phy).
 Study Design: The study employs experimental design, statistical analysis of the data and interpretation.
 Place and Duration of Study: Rivers State University demonstration farmland in Nkpolu- Oroworukwo, Mile 3 Diobu area of Port Harcourt, was used for this study. The piece of land is situated at Longitude 4°48’18.50” N and Latitude 6ᵒ58’39.12” E measuring 5.4864 m x 5.1816 m with a total area of 28.4283 square meter. Phytoremediation process monitoring lasted for 240 days; analyses were carried out monthly at 30 days’ interval.
 Methodology: The study was carried out on Crude Oil Polluted soil (PS) amended with bio-nutrient supplements (Spent Mushroom Substrate (SMS) and selected fungi (Aspergillus niger(AN) andMucor racemosus (MR)) used to stimulate and augment the indigenous microbial population present in a crude oil polluted soil thereby enhancing hydrocarbon reduction in pari per sue with phytoremediation (uptake of Crude oil by test plants) over a period of 240 days. Ten (10) experimental plots (two Control (Unpolluted and polluted soil without amendment) and eight polluted amended/treated plots) employing Randomized Block Design (each having dimensions: 100 x 50 x 30 cm LxBxH); formed and mapped out on agricultural soil and left fallow for 6 days before contamination on the seventh day; after which it was allowed for 21 days for proper contamination and exposure to natural environmental factors (to mimic soil crude oil spill site); thereafter nutrients/organics (biostimulating agents) and bioaugmenting organisms were applied. Baseline studies were carried out on soil profile before and after contamination, major parameters monitored and assayed were Total Petroleum Hydrocarbon (TPH) uptake by plant roots and stem, Polycyclic Aromatic Hydrocarbons (PAHs) and TPH reduction in soil. Other physicochemical properties analyzed in the soil from different plots were pH, Electrical Conductivity, Moisture Content, Total Nitrogen, Available Phosphorus, Potassium, Total Organic Carbon, Plant Height, Iron, Lead and Zinc at regular intervals; days 1, 60, 90, 120, 150, 180, 210 & 240. The rate of phytoremediation was estimated from percentage (%) uptake of Total petroleum hydrocarbon (TPH) in plant roots and stem from day 1 -240; while percentage (%) reduction of TPH and PAHs in soil was estimated from day 1 to the residual at day 240.
 Results: The test plants decreased significant amount of crude oil as revealed in TPH uptake in their roots and Stem. Mean amount and percentage Total Petroleum Hydrocarbon (TPH) uptake by Cyperus esculentus roots and stem were; 152.33±50.34mg/kg, 12.57±4.16% and 201.13±8.80mg/kg, 13.27±0.58% respectively; while that of Phyllanthus amarusroots and stem were 141.50±35.62mg/kg, 11.68±2.94% and 174.44±19.98mg/kg, 11.51±1.32% respectively; revealing higher Uptake of TPH in plant stem than roots. From the initial TPH contamination value of 5503.00mg/kg, it was observed that plots planted with Cyperus esculentus (TPH 5492.75±76.36mg/kg) showed higher reduction of TPH from soil than those planted with Phyllanthus amarus(TPH 5449.72±18.27mg/kg); while PAHs degradation/reduction showed a reverse trend with plots planted with Phyllanthus amarus (PAHs 28.72±2.74mg/kg; 60.46±5.77%) higher than plots planted with Cyperus esculentus
 s (PAHs 25.77±2.12mg/kg, 54.24±4.47%).
 Conclusion: Plots planted with Cyperus esculentus showed higher reduction of TPH from soil than those planted with Phyllanthus amarus while PAHs degradation/reduction in plots planted with Phyllanthus amarus was higher than plots planted with Cyperus esculentus. TPH uptake was higher in plant stems than roots; more so, plots amended with nutrient supplements showed significant higher percentage reduction in hydrocarbon in the polluted soil than unamended polluted soil. It is therefore recommended that Cyperus esculentus is a suitable plant species for phytoremediation of crude oil contaminated soil with high TPH value while Phyllanthus amarusis the best option in phytoremediation of polluted soil with high PAHs value, both in combination with bio-nutrient supplement.

Potential bifunctional rhizobacteria from crude oil sludge for hydrocarbon degradation and biosurfactant production

Biosurfactant produced by rhizobacteria has the potential to enhance the degradation of hydrocarbons, leading to more efficient phytoremediation. The aim of this work was to search for bifunctional hydrocarbon-degrading and biosurfactant-producing rhizobacteria. Isolation of bacteria was conducted from three sources (A: rhizosphere of Scirpus grossus planted in garden soils and B: rhizosphere of S. grossus planted in crude oil sludge and C: crude oil sludge) prior to degradation test. Seven isolated rhizobacteria from source B (coded as B1–B7) were screened for a hydrocarbon degradation test with an initial total petroleum hydrocarbon content of 56.13 mg/g. Similar isolated rhizobacteria were also found in source A and C. The best three isolates (B1, B3 and B6) and mixed culture of them, significantly degraded hydrocarbon with 16.2%, 8.4%, 39.7% and 34.8% removals, respectively. Subsequently, the three pure rhizobacteria and their mixture (B1 + B3 + B6) were screened for biosurfactant production through tests of oil displacement, drop collapse, emulsification and surface tension. All the pure rhizobacteria and mixed culture had given positive response for all the tests. The presence of biosurfactant produced by rhizobacteria was confirmed by SEM images in which the formation of exopolymers interconnecting individual cells into a complex network of mass was formed due to biosurfactant extraction from bacteria cell. Thus, the three isolated rhizobacteria (B1, B3, and B6), later identified as Bacillus sp. strain SB1, Bacillus sp. strain SB3 and Lysinibacillus sp. strain SB6, respectively, and their mixed culture can simultaneously biodegrade hydrocarbon and produce biosurfactant to enhance the degradation process.

Changes in Adsorption Characteristics of Heavy Metals and Organic Pollutants Following Pyrolytic Treatment of Petroleum-Contaminated Dredged Sediment

Objectives : This study investigated the changes in adsorption characteristics of dredged sediment for heavy metals and organic pollutants after petroleum contamination followed by pyrolytic treatment.Methods : Pyrolytic treatment was conducted at two heating temperatures, 300℃ and 500℃, for 30 min using muffle furnace. Sediment spiked with No. 6 Fuel Oil at initial total petroleum hydrocarbon (TPH) concentrations of 5,000-50,000 mg/kg was used. Sorption experiments were conducted for heavy metals (Cd, Cu, Pb, Zn, Ni, Hg, As, Cr), phenanthrene and bisphenol A using clean sediment (sediment before the petroleum spiking) and pyrolyzed sediment.Results and Discussion : Pyrolytic treatment at 500℃ showed excellent TPH removal efficiency, resulting in the residual concentration of less than 50 mg/kg for all initial TPH contamination levels. High efficiencies (> 98%) were observed for the sorptive removal of Cu, Zn and Pb in the aqueous phase for both the two sediments. The removal efficiencies of Ni and Cd from the aqueous phase using pyrolyzed sediment were 31% and 24% lower than those using clean sediment, respectively, due to the reduced oxygen-containing functional group content and specific surface area after the pyrolytic treatment. The sediment-water distribution coefficient (Kd) and sediment organic carbon-water distribution coefficient (Koc) values of bisphenol A and phenanthrene in pyrolyzed sediment were considerably higher than in clean sediment due to the high organic compound sorption affinity exhibited by carbonaceous matter that was generated during the pyrolytic sediment treatment.Conclusions : The capability of pyrolytic treatment of dredged sediment to notably improve its organic compound sorption capacity may be exploited for beneficial use of the treatment product. The product may be applied as fill and backfill, soil amendment, or in-situ sediment capping materials in highly industrialized areas where mitigation measures for organic contaminant migration are necessary.

Biodegradation of the petroleum hydrocarbons using an anoxic packed-bed biofilm reactor with in-situ biosurfactant-producing bacteria

The present study employed an anoxic packed bed biofilm reactor (AnPBR) inoculated with in-situ biosurfactant-producing bacteria for the biodegradation of petroleum wastewater. Highly acclimated biomass decreased the start-up phase period and with increasing the initial total petroleum hydrocarbon (TPH) concentration from 1.5 to 4 g/L was accompanied by TPH and chemical oxygen demand (COD) removal efficiencies of above 99% and 96%, respectively. Decreasing hydraulic retention time (HRT) from 24 to 6 h caused an increase in the specific hydrocarbon utilization rate value from 0.45 to 1.66 gTPH/gbiomass.d. Moreover, dehydrogenase activity, surfactin, and rhamnolipid reached 31.8 μgTF/gbiomass.d, 95.1, and 27.1 mg/L, respectively. The biodegradation kinetic coefficients such as K, Ks, Kd, Y and µmax were 0.784 (d−1), 0.005 (g/L), 0.138 (d−1), 0.569 (gVSS/gCOD), and 0.446 (d−1), respectively. Dropping of bioreactor performance, especially TPH removal efficiency from 99% to 37.6% in the absence of nitrate after 10 days, indicates anoxic metabolism has been the dominant biodegradation pathway. The effluent chromatogram of gas chromatography/flame ionization detector (GC/FID) showed aliphatic, cyclic aliphatic, and aromatic hydrocarbons efficiently degraded. According to the high degradation rate of AnPBR in different operational parameters, it can be recommended for the treatment of oil-contaminated wastewater.

Remediation and optimization of petroleum hydrocarbons degradation in contaminated water using alkaline activated persulphate

This study investigated the characterization of Nigerian crude oil using gas chromatography-mass spectrometry (GC-MS) and the efficiency of alkaline activated sodium persulphate in degrading petroleum hydrocarbons in crude oil-polluted water. Hydrocarbons (aliphatics and aromatics), non-hydrocarbons, and other constituents were characterized in crude oil samples. The ratio of hydrocarbons:non-hydrocarbons/others and aliphatics:aromatics is 86:14 and 45:55, respectively. Alkylated benzenes, toluene, o-xylene, fluorene, and naphthalenic compounds were the most common aromatic compounds. The majority of aliphatic compounds were n-alkanes and cyclic hydrocarbons, including cyclohexane and heptylcyclohexane. Degradation experiments were performed with different initial concentrations of sodium persulphate (0.3 M, 0.5 M and 0.7 M) with sodium hydroxide as an activator. Runs were carried out within 8 days. The total petroleum hydrocarbons (TPH) extraction was carried out and analyzed using gas chromatography flame ionization detector (GC-FID). From an initial TPH concentration of ~137 mg L−1 in water, near-complete degradation was achieved with 0.3 and 0.5 M oxidant dosage. With 0.7 M sodium persulphate, 76% TPH was degraded within 8 days. Radical quenching using sodium thiosulphate showed that the addition of the scavenger resulted in negligible changes in TPH concentration pre-and post-degradation using all three oxidant dosages. Thus, alkaline activated persulphate is effective for the remediation of petroleum hydrocarbon contamination.

Remediation of weathered diesel-oil contaminated soils using biopile systems: An amendment selection and pilot-scale study

Weathered diesel oil (WDO) has less biodegradable and volatile characteristics, and its bioremediation could be a challenge. In this study, the effectiveness of enhanced bioremediation via biopile processes for the cleanup of WDO-contaminated soils was evaluated. Six biopiles were constructed and operated with the following six different amendments addition: red bran (12 kg), water-soluble fertilizer (20 L/week), highly oxygenated water (20 L/d, dissolved oxygen = 25 mg/L), petroleum hydrocarbon-degrading bacterial culture (20 L/week), mixture of the above amendments, and natural attenuation (no amendment). Each biopile contained 5 m3 [2.5 m (L) × 2 m (W) × 1 m (H)] of WDO-contaminated soils [initial total petroleum hydrocarbon (TPH) concentrations = 3015 to 3785 mg/kg]. Soils were mixed with amendments and tilled for air supplement twice a week with soil moisture around 25%. Metagenomics analyses were applied to determine the microbial biodiversity and strains responsible for hydrocarbon biodegradation. Results show that the biopile system with mixed supplements (mixture group) had the highest TPH removal efficiency (79% of TPH removal) followed by red bran addition group with a removal efficiency of approximately 73% during the 42-day operation. The first-order TPH decay rates in mixture and red bran biopiles were around 3.2 × 10−2 1/d, which was 4.8 times higher than that obtained from natural attenuation biopile. Biopiles with red bran and mixture supplements contained carbon substrates and nutrients, which could effectively activate microbial activities and accelerate the TPH biodegradation. High carbon number compounds (C > 20) in WDO could be biodegraded within 24 days in the biopile with mixed amendments. Results from metagenomics study indicate that Sphingomonas and Pseudomonas might cause removal of heavy components (C24–30) and light components of petroleum hydrocarbons (C10–16), respectively.

Increase in Total Petroleum Hydrocarbons Removal Rate in Contaminated Mining Soil Through Bioaugmentation with Autochthonous Fungi During the Slow Bioremediation Stage

The removal of total petroleum hydrocarbons (TPHs) from contaminated mining soil was carried out under in vitro conditions. The aerobic consumption of TPH in the slow bioremediation stage via biostimulation with native microorganisms and biostimulation-bioaugmentation with autochthonous fungal isolates was evaluated. The initial TPH concentration was 70,880 ± 975 mg TPH/kg soil, soil was amended with nutrients at a C:N:P ratio of 100:15:1, the water content was adjusted to the soil field capacity, and batch microcosm reactors were incubated at room temperature (20.5 ± 3.1°C) for 90 days. The bioaugmentation process was tested using four hydrocarbonoclastic fungal strains isolated from the same contaminated mining soil individually and a mixed culture of the four isolates. The molecular characterization of the isolated fungi was based on sequence analysis of 18S rRNA, and the fungi were identified as Aspergillus niger MT786339.1, Aspergillus fumigatus MT786338.1, Aspergillus terreus MT786341.1, and Aspergillus flavus MT786340.1. The best TPH removal was achieved by inoculation with the fungal consortium (57 ± 1.97%) at 45 days (slow stage) after initiating the biostimulation process, followed by inoculation with Aspergillus niger (49 ± 1.2%), Aspergillus terreus (44 ± 0.67%), Aspergillus fumigatus (35 ± 0.98%), and Aspergillus flavus (32 ± 0.38%), while the degradation rate achieved with native microorganisms was only 21.6 ± 1.5%; statistical analysis of the results showed significant differences.