Removal Of Petroleum Hydrocarbons Research Articles

Microbial response to a port fuel spill: Community dynamics and potential for bioremediation

Following a fuel leakage inside a Portuguese maritime port, we conducted parallel 30-day experiments using contaminated seawater and fuel, sampled five days after the incident. This study aimed to (i)survey the native microbial community response to the spilled fuel and (ii)evaluate the efficacy of bioremediation, both biostimulation and bioaugmentation with a lyophilized bacterial consortium (Rhodococcus erythropolis, Pseudomonas sp.), in accelerating hydrocarbon degradation. Metabarcoding analysis revealed a shift in microbial communities, with increased abundance of hydrocarbon-degraders (e.g. Alcanivorax, Thalassospira). Ninety-five hydrocarbonoclastic bacteria were isolated, including key groups from the enriched communities. The lyophilized bacteria added in bioaugmentation, enhanced the abundance of hydrocarbon-degraders over time and were recovered throughout time. Bioremediation treatments favoured biodegradation, achieving over 60 % removal of total petroleum hydrocarbons after 15 days, contrasting with natural attenuation where almost no TPH was removed. This work highlights the potential of bioremediation technologies to accelerate hydrocarbon-degrading activity, for oil spills inside ports.

Seedling Emergence and Growth Can Be Improved by Char Carbon Created During Thermal Treatment of Petroleum-Impacted Soils

ABSTRACT Thermal treatment of soils to remove petroleum hydrocarbons alters soil properties in ways that limit germination potential for plants used in revegetation efforts. However, recent studies have shown that a char material with the potential to offset fertility-reducing effects is produced by the pyrolysis of hydrocarbons during treatment. In this study, seedling emergence and growth (14 days) of two plant species, soybean (Glycine max) and oat (Avena sativa), were evaluated in four soils of contrasting properties treated with 5% (by mass) oil addition and two levels of salt addition. Three temperatures (300, 425, and 550°C) of thermal desorption (TD) and one smolder remediation approach were employed to remove the oil prior to planting. Results indicate that seedling response to temperature of thermal treatment and salt addition is dependent both upon plant species and soil properties. Higher temperatures were necessary to remove crude oil to levels low enough to allow germination. The smoldering approach did not remove enough oil to allow germination. This is the first study to show that early shoot mass and root mass are improved following TD treatment compared with an untreated control under certain conditions. The outcomes will be valuable for designing TD treatments when revegetation is the goal.

Eco-friendly polyurethane composites with rice husk ash residue to remove petroleum hydrocarbons from aqueous media

Eco-friendly polyurethane composites with rice husk ash residue to remove petroleum hydrocarbons from aqueous media

Low dose phosphorus supplementation is conducive to remediation of heavily petroleum-contaminated soil—From the perspective of hydrocarbon removal and ecotoxicity risk control

Biostimulation by supplementing of nitrogen and phosphorus nutrients is a common strategy for remediation of petroleum-polluted soils. However, the dosage influence of exogenous nitrogen or phosphorus on petroleum hydrocarbon removal and soil ecotoxicity and microbial function remain unclear. In this study, we compared the efficiencies of hydrocarbon degradation and ecotoxicity control by experiment conducted over addition of inorganic nitrogen or phosphorus at C/N ratio of 100/10, C/N/P ratio of 100/10/1, and C/P ratio of 100/1 in a heavily petroleum-contaminated loessal soil with 12,320 mg/kg of total petroleum hydrocarbon (TPH) content. A 90-day incubation study revealed that low-dose of phosphorus addition with the C/P ratio of 100/1 promoted hydrocarbon degradation and reduced soil ecotoxicity. Microbial community composition analysis suggested that phosphorus addition enriched hydrocarbon degrader Gordonia and Mycolicibacterium genus. The key enzymes EC 5.3.3.8, EC 6.2.1.20 and EC 6.4.1.1 which referred to degradation of long-chain hydrocarbons, unsaturated fatty acids and pyruvate metabolism were abundance by phosphorus supplementation. While nitrogen addition at C/N ratio of 100/10 or C/N/P ratio of 100/10/1 inhibited hydrocarbon degradation and exacerbated soil ecotoxicity due to promoting denitrification and coupling reactions with hydrocarbons. Our results suggested that low-dose phosphorus addition served as a favorable strategy to promote crude oil remediation and ecotoxicity risk control in heavily petroleum-contaminated soil. Hence, the application of suitable doses of exogenous biostimulants is an efficient approach to restore the ecological functions of organically contaminated soils.

Ecological indicators and biological resources for hydrocarbon rhizoremediation in a protected area.

Spillage from oil refineries, pipelines, and service stations consistently leads to soil, food and groundwater contamination. Bacterial-assisted phytoremediation is a non-invasive and sustainable solution to eliminate or decrease the concentration of xenobiotic contaminants in the environment. In the present study, a protected area interested by a fuel discharge was considered to assess a bioremediation intervention. From the spill point, a plume of contamination flowed South-West into the aquifer, eventually reaching a wetland area. Soils, groundwaters and plants belonging to the species Scirpus sylvaticus (L.) were sampled. In the majority of the soil samples, concentrations of total petroleum hydrocarbons, both C ≤ 12 and C > 12, exceeded legal limits set forth in Directive 2000/60/EC. The analysis of diatom populations, used as ecological indicators, evidenced morphology alterations and the presence of Ulnaria ulna and Ulnaria biceps species, previously detected in hydrocarbon-polluted waters. Tests for phytotoxicity and phytodegradation, carried out in soil mesocosms, planted with Zea mays and Helianthus annuus, demonstrated that both species significantly contributed to the removal of total petroleum hydrocarbons. Removal of C ≤ 12 and C > 12 petroleum hydrocarbons was in the range of 80%-82% for Z. mays and 71%-72% for H. annuus. Microbial communities inhabiting high organic carbon and vegetated soils were more active in hydrocarbon degradation than those inhabiting subsoils, as evidenced by soil slurry experiments. The abundance of functional genes encoding toluene-benzene monooxygenase (tbmD) and alkane hydroxylase (alkB), quantified in environmental samples, confirmed that the plant rhizosphere recruited a microbial community with higher biodegradation capacity. Bacterial strains isolated from the sampling site were able to grow on model hydrocarbons (hexane, hexadecane and o-, m-, p-xylene) as sole carbon and energy sources, indicating that a natural bio-attenuation process was on-going at the site. The bacterial strains isolated from rhizosphere soil, rhizoplane and endosphere showed plant growth promoting traits according to in vitro and in vivo tests on Z. mays and Oryza sativa, allowing to forecast a possible application of bacterial assisted rhizoremediation to recover the protected area.

Remediation of petroleum‐contaminated soil by Fenton oxidation–pyrolysis

AbstractPetroleum‐contaminated soil (PCS) is urgently to be remediated due to its risk to ecological environment and human health. In this study, a Fenton oxidation–pyrolysis strategy was employed to accomplish effective petroleum removal and PCS remediation. The highest total petroleum hydrocarbon removal efficiency could achieve 99.6% after 2 h Fenton oxidation, with H2O2/Fe2+, 6:1, and pH 3, followed by pyrolysis at 370°C. The organic compositions of the soil after Fenton oxidation, the kinetics and process of the pyrolysis, morphologies and structures of the treated soil, as well as energy consumption and cost savings were comprehensively researched and analyzed. Through the Fenton oxidation–pyrolysis treatment, the macromolecules were effectively degraded and the contents of asphaltenes and resins were significantly reduced in the soil. Graphitized carbon was dominatingly existed after the pyrolysis. A 1.5 order reaction model was proposed to reasonably describe the pyrolysis remediation process of PCS. The Fenton oxidation–pyrolysis treatment can reduce energy consumption and cost compared with pyrolysis alone. This work not only offered an alternative approach of PCS remediation, but also provided theoretical guidance for practical soil remediation.

Synergistic removal of total petroleum hydrocarbons and antibiotic resistance genes in Yellow River Delta wetlands contaminated soil composting regulated by biogas slurry addition

The interactive effects between the emerging contaminant antibiotic resistance genes (ARGs) and the traditional pollutant total petroleum hydrocarbons (TPHs) in contaminated soils remain unclear. The synergistic removal of TPHs and ARGs from composted contaminated soil, along with the microbial mechanisms driven by the addition of biogas slurry, have not yet been investigated. This study explored the impact of biogas slurry on the synergistic degradation mechanisms and bacterial community dynamics of ARGs and TPHs in compost derived from contaminated soil. The addition of biogas slurry resulted in a reduction of targeted ARGs and mobile genetic elements (MGEs) by 9.96%–95.70% and 13.32%–97.66%, respectively. Biogas slurry changed the succession of bacterial communities during composting, thereby reducing the transmission risk of ARGs. Pseudomonas, Cellvibrio, and Devosia were identified as core microorganisms in the synergistic degradation of ARGs and TPHs. According to the partial least squares path model, temperature and NO3− indirectly influenced the removal of ARGs and TPHs by directly regulating the abundance and composition of host microbes and MGEs. In summary, the results of this study contribute to the high-value utilization of biogas slurry and provide methodological support for the low-cost remediation of contaminated soils.

Fulvic acid more facilitated the soil electron transfer than humic acid

Humus substances (HSs) participate in extracellular electron transfer (EET), which is unclear in heterogeneous soil. Here, a microbial electrochemical system (MES) was constructed to determine the effect of HSs, including humic acid, humin and fulvic acid, on soil electron transfer. The results showed that fulvic acid led to the optimal electron transfer efficiency in soil, as evidenced by the highest accumulated charges and removal of total petroleum hydrocarbons after 140 days, with increases of 161% and 30%, respectively, compared with those of the control. However, the performance of MES with the addition of humic acid and humin was comparable to that of the control. Fulvic acid amendment enhanced the carboxyl content and oxidative state of dissolved organic matter, endowing a better electron transfer capacity. Additionally, the presence of fulvic acid induced an increase in the abundance of electroactive bacteria and organic degraders, extracellular polymeric substances and functional enzymes such as cytochrome c and NADH synthesis, and the expression of m tr C gene, which is responsible for EET enhancement in soil. Overall, this study reveals the mechanism by which HSs stimulate soil electron transfer at the physicochemical and biological levels and provides basic support for the application of bioelectrochemical technology in soil.

Asynchronous application of modified biochar and exogenous fungus Scedosporium sp. ZYY for enhanced degradation of oil-contaminated intertidal mudflat sediment.

Intertidal mudflats are susceptible to oil pollution due to their proximity to discharges from industries, accidental spills from marine shipping activities, oil drilling, pipeline seepages, and river outflows. The experimental study was divided into two periods. In the first period, microcosm trials were carried out to examine the effect of chemically modified biochar on biological hydrocarbon removal from sediments. The modified biochar's surface area increased from 2.544 to 25.378 m2/g, followed by a corresponding increase in the hydrogen-carbon and oxygen-carbon ratio, indicating improved stability and polarity. In the second period, the effect of exogenous fungus - Scedoporium sp. ZYY on the bacterial community structure was examined in relation to total petroleum hydrocarbon (TPH) removal. The maximum TPH removal efficiency of 82.4% was achieved in treatments with the modified biochar, followed by a corresponding increase in Fluorescein diacetate hydrolysis activity. Furthermore, high-throughput 16S RNA gene sequencing employed to identify changes in the bacterial community of the original sediment and treatments before and after fungal inoculation revealed Proteobacteria as the dominant phylum. In addition, it was observed that Scedoporium sp. ZYY promoted the proliferation of specific TPH-degraders, particularly, Hyphomonas adhaerens which accounted for 77% of the total degrading populations in treatments where TPH removal was highest. Findings in this study provide valuable insights into the effect of modified biochar and the fundamental role of exogenous fungus towards the effective degradation of oil-contaminated intertidal mudflat sediments.

Contrasting Distribution of Microbial Communities, Functional Genes, and Antibiotic Resistance Genes in Produced Water Treatment Plants with Different Treatment Technologies

A massive volume of produced water (PW) generated in the process of oil extraction must be treated effectively due to its threat to the ecosystems and human health. Different biological treatment technologies have been used in wastewater treatment plant (WWTP) systems to treat PW. However, their influence on treatment performance has not been investigated. In this study, three PW treatment plants (PWTPs) with different treatment technologies were compared in the following aspects: microbial community structure and assembly, functional genes, and the spread of antibiotic resistance genes (ARGs). The results indicated that different biological treatment technologies led to the variations in the diversity and composition of the microbial community. Phylogenetic bin-based null model analysis (iCAMP) revealed that different treatment technologies deterministically drove the assembly of microbial communities, especially the genera associated with the removal of petroleum hydrocarbons. The results of the metagenomic analysis showed that the genes related to the degradation of alkanes and aromatic hydrocarbons were the most abundant in PWTP3, suggesting it had the highest petroleum degradation potential. In addition, the highest abundance of ARGs in PWTP1 indicated the potential facilitation of ARG dissemination in activated sludge systems. Network analysis indicated that the dissemination of ARGs in the PWTPs might be mediated by transposases.

Method of smoldering combustion for the treatment of oil sludge-contaminated soil

There is an urgent need to globally remediate oil sludge-contaminated soil (OSS). Smoldering combustion is a new low-energy approach for the treatment of organic waste. Therefore, the feasibility of smoldering combustion for the treatment of OSS was investigated in this study using a series of laboratory-scale experiments. The effective remediation of OSS was found to be achievable when the mass ratio of oil sludge in the sample reached 1/12 and above. Experimental results showed that smoldering at peak temperatures above 500 °C was found to completely remove petroleum hydrocarbons from the samples. The mass ratio of oil sludge in the sample had little effect on the distribution of the major elements (Si, Al, and Ca) in the smoldering products, and most of the minerals in the oil sludge adhered to the surface of the soil particles after smoldering. The smoldering heating environment is detrimental to the reusability of the soil, increases soil pH and available phosphorus content, and decreases organic carbon and total nitrogen content. Moreover, the influence of the airflow rate and material height on smoldering characteristics was investigated. Matching the appropriate airflow rate can help maintain optimal smoldering conditions, and smoldering remains stable with increasing material height. The addition of recovered oil to a sample with a low mass ratio of oil sludge can help with smoldering ignition and improve the removal efficiency of petroleum hydrocarbons. This study has confirmed that smoldering can be used to treat OSS within a broad range of oil sludge concentrations without pretreatment.

Performance evaluation of electrokinetic bioremediation for weathered petroleum hydrocarbon-contaminated soil

This study investigates the impact of Electrokinetic Remediation (EKR) time on total petroleum hydrocarbons (TPH) removal from soil, focusing on electroosmotic phenomena guided by Helmholtz-Smoluchowski theory. Soil samples were exposed to a constant 2 V/cm voltage gradient for 8, 16, and 24 hours, utilizing a 0.05 M Na2SO4 solution as an electrolyte to enhance soil conductivity. Biostimulation was combined with EKR, and TPH levels and microbial colonies (TPC) were monitored over a 4-week period. Maintaining optimal conditions (25-40°C, pH 6-8, 30-60% water content) was crucial for effective biodegradation. Results showed that a 24-hour EKR duration was most effective, achieving an 87.9% removal rate. The 16-hour duration closely followed at 85.7%, while the 8-hour duration exhibited lower effectiveness at 62.5%. TPC counts increased in the fourth week for the 16-hour and 24-hour durations but decreased for the 8-hour duration. Post-EKR, a gradual decline in TPH levels indicated electroosmotic flow’s (EOF) positive impact on TPH desorption and biodegradation. Electroosmosis influence was evident in varying TPH concentrations among segments after EKR, with higher levels near the cathode in the 16-hour and 24-hour durations. Lower TPH near the cathode in the 8-hour variation suggested electroosmosis-induced desorption, while reduced concentrations in regions A (near anode) and B (middle) resulted from biodegradation and microbial mobility due to electrophoresis. Confirmation of electroosmosis across all durations was supported by observed water content and EOF volume. The 24-hour duration exhibited the highest EOF proportion in the cathode chamber at 22.2%, followed by 16 hours at 16.1%, and 8 hours at 8.6%.

Oxygen atmosphere enhances ball milling remediation of petroleum-contaminated soil and reuse as adsorptive/catalytic materials for wastewater treatment

Ball milling is an environmentally friendly technology for the remediation of petroleum-contaminated soil (PCS), but the cleanup of organic pollutants requires a long time, and the post-remediation soil needs an economically viable disposal/reuse strategy due to its vast volume. The present paper develops a ball milling process under oxygen atmosphere to enhance PCS remediation and reuse the obtained carbonized soil (BCS-O) as wastewater treatment materials. The total petroleum hydrocarbon removal rates by ball milling under vacuum, air, and oxygen atmospheres are 39.83%, 55.21%, and 93.84%, respectively. The Langmuir and pseudo second-order models satisfactorily describe the adsorption capacity and behavior of BCS-O for transition metals. The Cu2+, Ni2+, and Mn2+ adsorbed onto BCS-O were mainly bound to metal carbonates and metal oxides. Furthermore, BCS-O can effectively activate persulfate (PDS) oxidation to degrade aniline, while BCS-O loaded with transition metal (BCS-O-Me) shows better activation efficiency and reusability. BCS-O and BCS-O-Me activated PDS oxidation systems are dominated by 1O2 oxidation and electron transfer. The main active sites are oxygen-containing functional groups, vacancy defects, and graphitized carbon. The oxygen-containing functional groups and vacancy defects primarily activate PDS to generate 1O2 and attack aniline. Graphitized carbon promotes aniline degradation by accelerating electron transfer. The paper develops an innovative strategy to simultaneously realize efficient remediation of PCS and sequential reuse of the post-remediation soil.

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.