Removal Of Petroleum Hydrocarbons Research Articles

Utilizing blast-furnace dust as a novel persulfate catalyst for the efficient removal of petroleum contaminants from soil

Petroleum-contaminated soil (PCS) poses a significant health risk. Catalyst-activated persulfate presents a promising technology for efficient treatment, while magnetic activated carbon catalysts are increasingly recognized for their easy recovery and robust performance in advanced oxidation processes (AOPs). However, the complex and costly preparation process has limited its widespread implementation. In this work, blast-furnace dust (BFD), a solid waste from steel mill, was used as a novel persulfate catalyst for the total petroleum hydrocarbons (TPHs) removal from PCS. With the BFD/SP system (0.1 g BFD and 1 mM PS for per gram soil, 4:1 water-to-soil ratio, and 40 °C), removal rates of 88.10% and 84.39% were achieved for TPHs in 0.7% and 3.0% PCS, respectively, surpassing most reported persulfate AOPs, highlighting its superior efficacy. The main reason was that Fe/C components on BFD surface could cooperate to cyclically produce diverse reactive oxygen species, including SO4•−, OH•, O2•− and 1O2. Furthermore, the amphiphilicity of BFD could promote both pollutants and oxidants to converge to its surface simultaneously, effectively utilizing short-lived ROS to degrade TPHs. Our findings implies that BFD is an excellent SP activator, providing an innovative approach for PCS treatment and promoting sustainable utilization of BFD.

Insights on dielectric barrier discharge plasma treatment of oil drilling cuttings

Oil drilling cuttings produced during oil exploration and extraction contain a high percentage of crude oil, ranging from 5% to 20% weight ratio (w/w) on a dry basis, and must be managed and treated properly before their release to the environment. In this study, non-thermal plasma (NTP) was investigated as an advanced oxidation process for the efficient, sustainable and cost-effective treatment of oil drilling cuttings. To this end, a plane-to-grid dielectric barrier discharge (DBD) reactor operating at atmospheric pressure was tested under different plasma conditions. The effect of treatment time, DBD power and air flow rate on the total organic carbon (TOC) removal efficiency was assessed and the energy efficiency of the process was determined. Within 10 min of plasma treatment, a very high TOC and total petroleum hydrocarbons (TPH) removal (∼90% and ∼99%, respectively) was achieved, while polycyclic aromatic hydrocarbons (PAHs) were degraded by ∼50% within 2 min of treatment. Depending on the experimental conditions, the energy efficiency of the process varied from 5 to 35 mg/kJ. From GC-MS analysis, several byproducts of the oxidation of oil drilling cuttings were identified, while the analysis of exhaust gases revealed that ∼85.1% of the removed organics from oil drilling cuttings was transformed to CO2 and CO. This study provides critical information on the effectiveness of the NTP process for the treatment of heavily contaminated solid wastes and can be considered as the critical step for its application for the treatment of solid wastes from the oil industry.

Биотехнология очистки щебеночного балласта и получения биодизеля

The authors have developed the biotechnology of railroad crashed stone ballast remediation with simultaneous producing of fatty acids suitable as biodiesel precursors using the algal-bacterial-yeast consortium and the biogeosorbent on its basis. 
 The efficiency of petroleum hydrocarbons removal during exposition to biological aditives under vigorous stirring was 97–98 %. Even on the repeated use of the same suspension, the optimal number of cycles to tumble ballast efficiently was determined to be 5. A decline of the petroleum hydrocarbon content to acceptable norms for the allowable residual content of oil in the soil was achieved in 90 days after plowed-down application of tank bottoms.
 Fatty acids of the suspension of the algal-bacterial-yeast consortium have a low value of the unsaturation degree suggesting the high biofuel oxidation stability. The cetane number, iodine value, and physicochemical properties of renewable fuels produced comply with the requirements of the European Standard EN 14 214 and the Russian National Standard 33131–2014, regardless of the exposure time.

Adsorptive removal of volatile petroleum hydrocarbons from aqueous solution by zeolite imidazole framework (ZIF-8) and iron oxide (Fe3O4) nanoparticles

Volatile petroleum hydrocarbons (VPHs), including pentane, ethylbenzene, methyl tert-butyl ether, toluene, and n-hexane, are often found on the surface and underground water due to industrial activities. As such the removal of VPHs is crucial by a vital task that requires great attention, especially in oil-rich countries. Thus, in this study, the adsorptive removals of VPHs from an aqueous solution by zeolite imidazole framework-8 (ZIF-8) and iron oxide nanoparticles (IONs) were investigated. The characterization results revealed that ZIF-8 has a higher surface area, and larger pore volume, and is more thermally stable than IONs. Fourier transform infrared spectra have found peaks corresponding to functional groups such as Zn-N, C-N, C-H, and CN in ZIF-8 and Fe-O and hydroxyl groups in IONs confirming the successful synthesis of the adsorbents nanoparticles. Furthermore, the zeta potential values were − 10 mV and − 17 mV for ZIF-8 and IONs, respectively; suggesting good stability while Brunauer, Emmett, and Teller (BET) specific surface area results revealed that both adsorbents have a high surface area of 1268 m2/g for ZIF-8 and 130.8 m2/g for IONs. The optimum pH for the removal of VPHs for both adsorbents was observed to be pH 8, with the highest removal efficiency reaching 82.2% and 63.6% for ZIF-8 and IONs, respectively. Isotherm model studies revealed that the adsorption data was best fit using the Langmuir model indicating monolayer adsorption. The maximum adsorption capacities (Qm) of VPHs onto ZIF-8 was 5.51 mg/g and onto IONs was 1.459 mg/g at 45◦C, respectively. Lastly, the thermodynamic studies revealed that the reaction was endothermic, spontaneous, and had a good affinity. The results demonstrated the great potentiality of ZIF-8 application as a benchmark adsorbent for the removal of VPHs compounds. In this study for the first time, the wide matrix of VPHs was attempted to be removed from a real wastewater sample using ZIF-8 and IONs. The results designate that ZIF-8 and IONs as good adsorbents for the removal of a wide range of VPHs from a water matrix.

Petroleum hydrocarbon degradation of husk biochar product carrying biofilm-forming bacteria

Environmental pollution problems caused by petroleum and its derivatives such as polycyclic aromatic hydrocarbons (PAHs) has remarkably increased and become a major global threat to human health and ecological equilibrium, resulting in a crucial need for remediation. Recently, in order to solve this problem, biofilm is one of the biodegradation approaches which could degrade and transform oil components effectively. Moreover, to enhance the petroleum hydrocarbons removal efficiency and easy to apply in any place bio-carriers, biochar was used to attach biofilm-forming microorganisms. Biochar is not only used as a carrier for microorganisms but also a source of substrates to help absorb a part of aromatic compounds. Therefore, in this investigation, we used the mixture of multiple petroleum-degrading and biofilm-forming bacterial strains immobilized on husk biochar to create an oil-degrading product. The ability of oil-degrading bacteria immobilized on biochar, planktonic bacteria and biochar without bacteria on the elimination of total petroleum hydrocarbons and several aromatic hydrocarbons was investigated. The results indicated that using husk biochar as a carrier for biofilm-forming bacteria to attach on could considerably enhance the removal efficiency of oil components. At 50 kg/batch scale, the formed product could remove 99% of total petroleum hydrocarbons with the initial amount of 4.786 mg/l and over 96% of aromatic hydrocarbons including anthracene, naphthalene, phenanthrene and pyrene with the initial amount of 250 mg/l. The obtained product is porous, black, with particle size of 1-3 mm, cell density of ≥ 109 CFU/g(ml), stable for use ≥ 6 months and safe for the environment. In general, the obtained results highpoint the great possible of applying this product in the treatment of oil contaminated soil and water.

Optimisation of soil washing method for removal of petroleum hydrocarbons from contaminated soil around oil storage tanks using response surface methodology

Total petroleum hydrocarbons (TPHs), which are often found in soil, water, sediments, and air. These compounds are a type of pollutant that can have a serious negative impact on living things and human health. Soil washing method is a remediation technique used to remove contaminants from the soil. This process involves the use of water or other solvents to extract contaminants from the soil, followed by separation and disposal of the contaminated solution. This research engineered the effectiveness of soil washing method to remove TPHs from a genuine, sullied soil sample. After analyzing the physical and chemical properties of the soil, the Box-Benken Design (BBD) technique was used to optimize the variables that influence the process's effectiveness. A quadratic model was suggested based on the BBD design, correlation coefficients, and other factors. The minimum, maximum and mean removal of TPHs during the stages of the study were 63.5, 94.5 and 76.7%, respectively. The correlation between the variables was strong, as shown by the analysis of variance (ANOVA), F-value (1064.5) and P-value (0.0001), and the proposed model was highly significant. The most effective soil washing method (SWM) was obtained with pH 7.8, liquid to solid ratio 50:1, reaction time 52 min, surfactant concentration 7.9 mg kg−1, and three washings. A removal rate of 98.8% was accomplished for TPHs from the soil in this context. The kinetic results indicate that the kinetic of TPHs removal follows the first-order kinetics (R2 = 0.96). There was not a major difference in the process's efficiency based on temperature. The removal efficiency heightened from 0 to 150 rpm and then remained steady. Introducing air flow increased the rate of removal, and the combination of ultrasonic waves with the reaction environment increased the process efficiency and decreased the time for the process and the amount of times it needed to be washed. An analysis of the washed soil both physically and chemically revealed a substantial decrease in the concentration of other elements.

Optimization and purification of bioproducts from Bacillus velezensis PhCL fermentation and their potential on industrial application and bioremediation

Bioproduction is considered a promising alternative way of obtaining useful and green chemicals. However, the downstream process of biomolecules has been one of the major difficulties in upscaling the application of bioproducts due to the high purification cost. Acid precipitation is the most common method for purifying biosurfactants from the fermentation broth with high purity. However, the use of strong acids and organic solvents in solvent extraction has limited its application. Hence, in this study, a new strain of Bacillus velezensis PhCL was isolated from phenolic waste, and its production of amylase had been optimized via response surface methodology. After that, amylase and biosurfactant were purified by sequential ammonium sulfate precipitation and the result suggested that even though the purified crude biosurfactant had a lower purification fold compared to the acid precipitation, the yield was higher and both enzymes and biosurfactant also could be recovered for lowering the purification cost. Moreover, the purified amylase and crude biosurfactant were characterized and the results suggested that the purified crude biosurfactant would have a higher emulsion activity and petroleum hydrocarbon removal rate compared to traditional surfactants. This study provided another approach for purifying bioactive compounds including enzymes and biosurfactants from the same fermentation broth and further explored the potential of the crude purified biosurfactant in the bioremediation of polycyclic aromatic hydrocarbons and petroleum hydrocarbons.

Co-culture of Acinetobacter sp. and Scedosporium sp. immobilized beads for optimized biosurfactant production and degradation of crude oil

The widespread exploration and exploitation of crude oil has increased the prevalence of petroleum hydrocarbon pollution in the marine and coastal environment. Bioremediation of petroleum hydrocarbons using cell immobilization techniques is gaining increasing attention. In this study, the crude oil degradation performance of bacterial and fungal co-culture was optimized by entrapping both cells in sodium-alginate and polyvinyl alcohol composite beads. Results indicate that fungal cells remained active after entrapment and throughout the experiment, while bacterial cells were non-viable at the end of the experimental period in treatments with the bacterial-fungal ratio of 1:2. A remarkable decrease in surface tension from 72 mN/m to 36.51 mN/m was achieved in treatments with the bacterial-fungal ratio of 3:1. This resulted in a significant (P < 0.05) total petroleum hydrocarbon (TPH) removal rate of 89.4%, and the highest degradation of n-alkanes fractions (from 2129.01 mg/L to 118.53 mg/L), compared to the other treatments. Whereas PAHs removal was highest in treatments with the most fungal abundance (from 980.96 μg/L to 177.3 μg/L). Furthermore, enzymes analysis test revealed that catalase had the most effect on microbial degradation of the target substrate, while protease had no significant impact on the degradation process. High expression of almA and PAH-RHDa genes was achieved in the co-culture treatments, which correlated significantly (P < 0.05) with n-alkanes and PAHs removal, respectively. These results indicate that the application of immobilized bacterial and fungal cells in defined co-culture systems is an effective strategy for enhanced biodegradation of petroleum hydrocarbons in aqueous systems.

Application of photocatalytic proxone process for petrochemical wastewater treatment

Industrial wastewaters are different from sanitary wastewaters, and treatment complications due to their unique characteristics, so biological processes are typically disrupted. High chemical oxygen demand, dye, heavy metals, toxic organic and non-biodegradable compounds present in petroleum industry wastewater. This study intends to optimize the photocatalytic proxone process, utilizing a synthesized ZnO–Fe3O4 nanocatalyst, for petroleum wastewater treatment. The synthesis of ZnO–Fe3O4 was done by air oxidation and layer-by-layer self-assembly method and XRD, SEM, EDAX, FT-IR, BET, DRS, and VSM techniques were used to characterize the catalyst. Central composite design (CCD) method applied to investigated the effect of pH (4–8), reaction time (30–60 min), ozone gas concentration (1–2 mg/L-min), hydrogen peroxide concentration (2–3 mL/L) and the amount of catalyst (1–0.5 g/L) on the process. In the optimal conditions, biological oxygen demand (BOD5) and total petroleum hydrocarbon (TPH) removal, reaction kinetic, and synergistic effect mechanisms on the process were studied. Based on the ANOVA, a quadratic model with R2 = 0.99, P-Value = 0.0001, and F-Value = 906.87 was proposed to model the process. Based on the model pH = 5.7, ozone concentration = 1.8 mg/L-min, hydrogen peroxide concentration = 2.5 mL/L, reaction time = 56 min, and the catalyst dose = 0.7 g/L were proposed as the optimum condition. According to the model prediction, an efficiency of 85.3% was predicted for the removal of COD. To evaluate the accuracy of the prediction, an experiment was carried out in optimal conditions, and experimentally, a 52% removal efficiency was obtained. Also, at the optimum condition, BOD5 and TPH removal were 91.1% and 89.7% respectively. The reaction kinetic follows the pseudo-first-order kinetic model (R2 = 0.98). Also, the results showed that there is a synergistic effect in this process. As an advanced hybrid oxidation process, the photocatalytic proxone process has the capacity to treat petroleum wastewater to an acceptable standard.

Use Straw in the Removal of Petroleum Hydrocarbons from Industrial Wastewater for South Refinery Company in Basrah Province

In this study, a straw was employed at the coagulation and flocculation of total petroleum hydrocarbons from industrial wastewater in the refinery oil company in Basra province, using the design of experiments approach using the method of (analyzing screening designs). Independent factors in the experiments (pH, dose of the substance used for removal, and time of the experiment). Furthermore, the link between the test's independent variables and their impact on the elimination process. As previously stated, the results revealed that the square model is the optimum model in this study, and the maximum removal was 100% at PH (3), dose (2) g, and time (30) minutes, and a comparison was made between the experimental design DOE and the multiple linear regression MLR to determine the effectiveness of the system used, which proved its great effectiveness. MLR was too distant from the real consequences of DOE removal when there was a strong convergence between the real and expected impacts of DOE removal.

New Bioretention Drainage Channel as One of the Low-Impact Development Solutions: A Case Study from Poland

In recent years, as a result of intensive urbanisation, a significant increase in the surface of impermeable areas has been observed, which results in changes in the hydrological cycle of catchments. In order to counteract these changes, low-impact development (LID) solutions are increasingly being implemented in urban catchments, including bioretention systems. Taking this into account, a new bioretention drainage channel (BRC) was designed, whose main task is retention, infiltration, and pre-treatment of rainwater. The pilot laboratory tests carried out on two BRC prototypes (K1 and K2) showed that the average rate of reduction of mineral-suspended solids from rainwater was 69% and 57%, respectively, for K1 and K2. Analysing the results of the research, it was found that the bioretention drainage channel is characterised by very high efficiency in removing petroleum hydrocarbons from rainwater, and the reduction rate of these pollutants for both the K1 and K2 channels was close to 100%. In turn, hydrodynamic studies carried out on the model of the urban catchment showed that the implementation of BRCs will reduce the peak runoff by more than 82%, and the maximum flow in the sewage network by 83%.

Comparative study of bioremediation of crude oil spillage using Cissus populnea stem and root as bio-sorbents

The total petroleum hydrocarbon concentration decrease at the initial and final bioremediation across different variable and the comparative effect of roots and stem of Cisuss populnea biosorbent were studied. 25 g of soil was weighed into different plate, contaminated with about 10 ml of crude oil, the plate was labeled as BI, CI DI, BF, CF and DF (stem), (root) across 3 g, 6 g, and 9 g variables and A (soil and crude oil mixture) as control for initial and final bioremediation. 1 g of each contaminated soil sample was extracted using mechanical shaker at room temperature and the extracts were analyzed using GC/MS the results showed that the initial treatment of stem biosorbent were 358.47455 ppm, 248.02045 ppm, 249.97273 ppm respectively and the final treatment after 4 weeks of biodegradation were 173.40636 ppm, 70.44364 ppm, 45.60818 ppm and control 757.39864 ppm. The total effect removal of Total petroleum hydrocarbon obtained were 51.6%, 75.2% and 81.8%, while the initial treatment of the root biosorbent were 366.72762 ppm, 347.75909 ppm, 337.04227ppm, after 4 weeks of biodegradation, the Total petroleum hydrocarbon concentration decreases to 143.6982 ppm, 60.05455 ppm, 52.21045 ppm and control 757.39864 ppm and the effect removal were 60.8%, 82.7% and 84.5%.

Sorption and Removal of Petroleum Hydrocarbons from Brackish Water by Hydrophobic Sorbents Immobilized with Fungi

This study investigates the effects of immobilizing fungi on the straw’s performance as an oil sorbent. The buoyancy of the straw with fungi was found to be unaffected by the immobilization process. Even when sorbed with oil, the straw floated on the water’s surface throughout the 14-day test period. The sorption kinetics of the oil appeared similar in the straw with and without immobilized fungi, regardless of beaker shaking. However, the fraction of non-extractable oil was higher in the straw with fungi and shaking compared to the straw without shaking. This observation suggests the potential initiation of oil mining. Based on these results, it is suggested that instead of leaving the straw with fungi and oil in the water, removing it may be beneficial and allow for oil degradation and straw decomposition on land.

Phytoremediation and bacterial community dynamics of diesel- and heavy metal-contaminated soil: Long-term monitoring on a pilot scale

The objective of this study was to investigate the long-term phytoremediation characteristics and the bacterial community structure in diesel- and heavy metals-contaminated soil on a pilot scale. Soil was contaminated with diesel, Cu, Pb, and Cd. Festuca arundinacea (tall fescue) seedlings were cultivated in the co-contaminated soil, and the phytoremediation performance was monitored for 571 days. The maximum total petroleum hydrocarbon (TPH) removal rate was 62.6%, with residual TPHs remaining at the end of the experiment. Of the three heavy metals, Cd had the highest uptake efficiency in tall fescue, with a bioconcentration factor of 0.58. In the bacterial community, the most dominant bacterial genera exhibited either petroleum hydrocarbon biodegradability or heavy-metal tolerance. Correlation analysis revealed that ambient temperature did not significantly affect phytoremediation performance, while soil pH and organic content had significant effects on pollutant concentrations in the soil. The results of this study, obtained from the long-term monitoring of phytoremediation on a pilot scale, provide useful information on pollutant behavior and bacterial community dynamics that can be employed in the development of phytoremediation strategies for soils co-contaminated with diesel and heavy metals.

Synergistic effect of adsorption and photocatalytic degradation of oilfield-produced water by electrospun photocatalytic fibers of Polystyrene/Nanorod-Graphitic carbon nitride

Graphitic carbon nitride with nanorod structure (Nr-GCN) was synthesized using melamine as a precursor without any other reagents by hydrothermal pretreatment method. XRD, FTIR, SEM, N2 adsorption-desorption from BET, UV–Vis DRS spectroscopy, and photoluminescence were used to characterize the prepared samples. Also, the photoelectrochemical behavior of nanoparticles was studied by photocurrent transient response and cyclic voltammetry analysis. Polystyrene (PS) fibrous mat was fabricated by electrospinning technique and used as a support for the stabilization of the nanoparticles. The performance of the synthesized nanoparticles and photocatalytic fibers (PS/Nr-GCN) was evaluated in oilfield-produced water treatment under visible light irradiation. During this process, oil contaminants were adsorbed by hydrophobic polystyrene fibers and simultaneously degraded by Nr-GCN. The removal efficiency of chemical oxygen demand (COD) has been obtained 96.6% and 98.4% by Nr-GCN and PS/Nr-GCN, respectively, at the optimum conditions of pH 4, photocatalyst dosage 0.5 g/L, COD initial concentration 550 mg/L, and illumination time 150 min. The gas chromatography-mass spectroscopy analysis results showed 99.3% removal of total petroleum hydrocarbons using photocatalytic fibers of PS/Nr-GCN. The results demonstrated that the GCN has outstanding features like controllable morphology, visible-light-driven, and showing high potential in oily wastewater remediation. Moreover, the synergistic effect of adsorption and photocatalytic degradation is an effective technique in oilfield-produced water treatment.

Nano-bioremediation: an eco-friendly and effective step towards petroleum hydrocarbon removal from environment

Global concern about petroleum hydrocarbon pollution has intensified and gained scientific interest due to its noxious nature, high persistence in environmental matrices, and low degradability. One way to address this is by combining remediation techniques that could overcome the constraints of traditional physio-chemical and biological remediation strategies. The upgraded concept of bioremediation to nano-bioremediation in this direction offers an efficient, economical, and eco-friendly approach to mitigate petroleum contaminants. Here, we review the unique attributes of different types of nanoparticles and their synthesis procedures in remediating various petroleum pollutants. This review also highlights the microbial interaction with different metallic nanoparticles and their consequential alteration in microbial as well as enzymatic activity which expedites the remediating process. Besides, the latter part of the review explores the application of petroleum hydrocarbon degradation and the application of nano supports as immobilizing agents for microbes and enzymes. Further, the challenges and the future prospects of nano-bioremediation have also been discussed.

Hydrocarbon bioremediation in a pilot-scale: A combination of bioaugmentation, phytoremediation, and vermiremediation

This work aimed to validate the removal of total petroleum hydrocarbons (TPH) in a pilot system (on-site). Six piles of oil-contaminated soil were treated with 1) bioremediation (BIO) by three simultaneous technologies (bioaugmentation (bacterial consortium), phyto- (Panicum maximum) and vermiremediation (Pontoscolex corethrurus)), and compared with 2) natural attenuation (NA). Removal of alkanes, polycyclic aromatics (PAH), total petroleum hydrocarbons (TPH), and bacterial diversity were evaluated at 0, 35, 70, and 112 days. Biomass and number of shoots of P. maximum, the secondary vegetation, and the abundance of meso and macrofauna were measured initially and at the end. After 112 days, BIO significantly removed more alkanes (76%), PAH (68%), and TPH (76%) than NA treatment (23%, 19%, 24%). P. maximum biomass increased significantly (300%), with 97.3 ± 11.8 shoots m−2. After 112 days, the secondary plants Lippia dulcis, Taraxacum officinale, Bidens pilosa and bacterial phylum Actinobacteria (18%) were the most abundant. The abundance of the earthworm Protozapotecia australis was reduced, while the most abundant group of mesofauna was Acari (56%–71%). This combination of technologies improved the development of grass and secondary plants, which generated a more favorable microhabitat for soil organisms to remove TPH more efficiently.

The use of a pumice stone in removal of petroleum hydrocarbons from industrial wastewater through coagulation and flocculation

Background: Petroleum hydrocarbons that are released from industrial processes cause damage to aquatic life and degrade ecosystems by accumulating in the food chain, allowing living organisms to produce toxic secretions. Methods: In this study, a pumice stone was used to remove total petroleum hydrocarbons (TPHs) from industrial wastewater in the south refinery company in Iraq/Basrah by coagulation and flocculation processes using the design of experiments (DOE) approach using the method of analyzing screening designs and measurement of the samples using GC instrument. Results: The maximum removal was 99% at pH 3, coagulation dose of 0.5 g, and time of 60 min, and a comparison was made between the DOE and the multiple linear regression (MLR) to determine the effectiveness of the system used, which proved its incredible effectiveness. Conclusion: According to the results, a great convergence between the actual and prediction results of removal was found, while MLR was very far from the actual and predicted removal results. The high efficiency of pumice stone was found in removing petroleum hydrocarbons from the industrial wastewater of the South Refineries Company. Pumice stone is widely available in the market and cheap economically.

Feasibility study of porous media for treating oily sludge with self-sustaining treatment for active remediation technology.

Oil sludge is the primary pollutant produced by the petroleum industry, which is characterized by large quantities, difficult disposal, and high toxicity. Improper treatment of oil sludge will pose a severe threat to the human living environment. Self-sustaining treatment for active remediation (STAR) technology has a specific potential for treating oil sludge, with low energy consumption, short remediation time, and high removal efficiency. Given the low smoldering porosity, poor air permeability, and poor repair effect of oil sludge, this paper considered coarse river sand as the porous medium, built a smoldering reaction device, conducted a comparative study on smoldering experiments of oil sludge with and without river sand, and studied the key factors affecting smoldering of oil sludge. The study shows that the repair effect is greatly improved by adding river sand, increasing the pore, and improving air permeability, and the total petroleum hydrocarbon removal rate reaches more than 98%, which meets the requirements of oil sludge treatment. When the mass ratio of oil sludge to river sand (sludge-sand ratio) is 2:1, the flow velocity is 5.39 cm/s, and the particle size of the medium is 2-4 mm. In addition, the best conditions for smoldering occur. The average peak temperature, average propagation speed, and average removal efficiency are relatively high. The peak temperature occurs in a short time; the heating time is also short, and the heat loss is low. Moreover, the generation of toxic and harmful gases is reduced, and secondary pollution is hindered. The experiment indicates that the porous media play a crucial role in the smoldering combustion of oil sludge.

Biochar-Assisted Catalytic Pyrolysis of Oily Sludge to Attain Harmless Disposal and Residue Utilization for Soil Reclamation.

Pyrolysis of oily sludge (OS) is a feasible technology to match the principle of reduction and recycling; however, it is difficult to confirm the feasible environmental destination and meet the corresponding requirements. Therefore, an integrated strategy of biochar-assisted catalytic pyrolysis (BCP) of OS and residue utilization for soil reclamation is investigated in this study. During the catalytic pyrolysis process, biochar as a catalyst intensifies the removal of recalcitrant petroleum hydrocarbons at the expense of liquid product yield. Concurrently, biochar as an adsorbent can inhibit the release of micromolecular gaseous pollutants (e.g. HCN, H2S, and HCl) and stabilize heavy metals. Due to the assistance of biochar, pyrolysis reactions of OS are more likely to occur and require a lower temperature to achieve the same situation. During the soil reclamation process, the obtained residue as a soil amendment can not only provide a carbon source and mineral nutrients but can also improve the abundance and diversity of microbial communities. Thus, it facilitates the plant germination and the secondary removal of petroleum hydrocarbons. The integrated strategy of BCP of OS and residue utilization for soil reclamation is a promising management strategy, which is expected to realize the coordinated and benign disposal of more than one waste.