A highly efficient method with low energy and water consumption in biodegradation of total petroleum hydrocarbons of oily sludge

Optimization and mechanism of oily sludge treatment by a synergistic approach of high-speed stirring cleaning integrated with thermal-activated Na2S2O8 oxidation

Oily sludge not only seriously pollutes the ecological environment, but also endangers human health. Additionally, the complex properties pose significant challenges in its treatment. The single technology has limited capacity and poor treatment effect. Consequently, the combined technology is being developed due to the exceptional treatment effect. Herein, a new combined technology was proposed to treat oily sludge, which combined high-speed stirring cleaning with thermal-activated Na2S2O8 oxidation. The bulk of petroleum pollutants were efficiently removed by high-speed stirring cleaning firstly, and the residual petroleum pollutants were decomposed by thermal-activated Na2S2O8. After treatment, the oil content of the oily sludge decreased from 13.81 % to 0.47 % with the removal rate of 96.6 % under the optimal conditions, which had reached the discharge and reuse standards. The high-speed stirring had remarkable removal effect on saturated hydrocarbons, aromatic hydrocarbons and resins. In addition to the three components mentioned above, thermal-activated Na2S2O8 also had excellent removal effect on asphaltenes in the cleaned oily sludge based on the strong oxidation effect of SO4-· and OH·. This work demonstrates a new method to treat oily sludge efficiently, which not only reduces the burden of petrochemical industries and provides support for their green development, but also has important scientific significance for environmental protection and environmental management.

Resuscitation-promoting factors: Novel strategies for the bioremediation of crude oil-contaminated soils

Soil contamination with petroleum hydrocarbons is a major environmental concern. The bioremediation of these soils can be restricted because of the entry of potential microbial degraders into the viable but nonculturable (VBNC) state under unfavorable environmental conditions. Resuscitation agents can stimulate the resuscitation and growth of the bacterial population, improving their degradation capabilities. This study evaluated the efficacy of resuscitation-promoting factor (Rpf) in enhancing the biodegradation of total petroleum hydrocarbons (TPHs) in crude oil-contaminated soils, with a focus on both indigenous and augmented bacterial communities without prior resuscitation. Unlike earlier studies that focused solely on Rpf-treated populations, this study investigated the simultaneous application of Rpf and traditional biostimulation and bioaugmentation processes. Additionally, this work is the first to compare Rpf with other resuscitation agents, including supernatant Rpf (SRpf) and Micrococcus luteus. The results indicated that Rpf-supplemented biostimulation (BS + Rpf) and bioaugmentation (BAS + Rpf) processes achieved 67% and 75% degradation of 31,408 mg kg-1 TPHs within 91 days, respectively, whereas 49% and 64% degradation occured by the BS and BAS processes, respectively. Rpf stimulated the growth of bacterial populations, contributing to enhanced bioremediation of contaminated soil. Furthermore, phytotoxicity decreased with decreasing TPH concentration. These findings also demonstrated that, compared with Rpf, SRpf and M. luteus presented similar TPH removal efficiencies and seemed to be suitable alternatives to recombinant Rpf. These results provide novel insights into the activation of native bacteria by the application of resuscitation agents, demonstrating a promising approach for the bioremediation of crude oil-contaminated soils.

An improved process for removal and recovery of heavy petroleum from solids using a ferrate-based hybrid oxidant

Persulfate oxidants are widely used in soil remediation and wastewater treatment but perform poorly in degrading polycyclic aromatic hydrocarbons (PAHs), especially heavy fractions in solids. Herein, we propose the utilization of a green peroxymonosulfate-ferrate-FeS (PFI) oxidant as a promising process aid for remediating soils contaminated with heavy petroleum components, including asphaltenes and resins. The PFI oxidant could degrade heavy petroleum fractions because of dual activation of the peroxymonosulfate and ferrate by FeS at ambient conditions. Nevertheless, when dealing with soil with high oil content (>10%), the degradation efficiency remains limited (<30%) regardless of the quantity of oxidants employed. Surface elemental analysis shows that a coating of secondary products (Fe(OH)3, Fe2O3) on the surface and in pores of the soil-pollutant matrix explains the failure of oxidation and inefficient use of oxidant. To address this issue, a strategy of pre-solvent extraction-oxidation hybrid process with sequent acidic washing is proposed, where dichloromethane serves as the solvent, and PFI acts as the oxidant. In this system over 90% of the oil could be recovered with an oxidation efficiency of 80% by alleviating the problem of iron oxide coating the matrix surface. The oxidant consumption is also reduced to 70 wt% of the sludge. The PFI oxidant is found to exhibit excellent universality in treating oily sludge with low petroleum content (<2%), reducing the petroleum content in the residue to less than 0.3 wt% (meeting the national standards). The degradation of low oil content sludge by the PFI oxidant followed pseudo first-order kinetics. These findings not only elucidate the failure of PFI oxidation for high oil content oily sludge and identify its potential engineering application range, but also offer a practical strategy for processing petroleum-contaminated soil with varying oil contents through wet oxidation.

Simultaneous production of biosurfactant and extracellular unspecific peroxygenases by Moesziomyces aphidis XM01 enables an efficient strategy for crude oil degradation

Crude oil is a hazardous pollutant that poses significant and lasting harm to human health and ecosystems. In this study, Moesziomyces aphidis XM01, a biosurfactant mannosylerythritol lipids (MELs)-producing yeast, was utilized for crude oil degradation. Unlike most microorganisms relying on cytochrome P450, XM01 employed two extracellular unspecific peroxygenases, MaUPO.1 and MaUPO.2, with preference for polycyclic aromatic hydrocarbons (PAHs) and n-alkanes respectively, thus facilitating efficient crude oil degradation. The MELs produced by XM01 exhibited a significant emulsification activity of 65.9% for crude oil and were consequently supplemented in an "exogenous MELs addition" strategy to boost crude oil degradation, resulting in an optimal degradation ratio of 72.3%. Furthermore, a new and simple "pre-MELs production" strategy was implemented, achieving a maximum degradation ratio of 95.9%. During this process, the synergistic up-regulation of MaUPO.1, MaUPO.1 and the key MELs synthesis genes contributed to the efficient degradation of crude oil. Additionally, the phylogenetic and geographic distribution analysis of MaUPO.1 and MaUPO.1 revealed their wide occurrence among fungi in Basidiomycota and Ascomycota, with high transcription levels across global ocean, highlighting their important role in biodegradation of crude oil. In conclusion, M. aphidis XM01 emerges as a novel yeast for efficient and eco-friendly crude oil degradation.

The methods for improving the biodegradability of oily sludge: a critical review

Biological degradation method, as an environmentally friendly, low-carbon, and clean pollution treatment technology, is widely used for the harmless disposal of oily sludge. The biodegradability of oily sludge with stable emulsification system, high oil, and water content is poor. Therefore, it is necessary to pre-treat the oily sludge to improve its biodegradability, including recover the petroleum resources and remove heavy metals and bio-toxic organic matters. This review systematically summarizes five oily sludge treatment methods and their influences on sludge biodegradability, including pyrolysis, chemical hot washing, solvent extraction, chemical oxidation, and hydrothermal. Pyrolysis at temperatures above 750 °C produces high molecular weight polycyclic aromatic hydrocarbons, chemical hot washing and chemical oxidation would cause secondary pollution, solvent extraction method could not be applied due to the high cost and high toxicity of the extractant, and the oil removal of hydrothermal method is inefficient. Additionally, the principles, advantages, and disadvantages of those treatments and the factors affecting microbial degradation were analyzed, which provide the development direction of pretreatment technology to improve the biodegradability of oily sludge.

Pyrolysis characteristics and product distribution of oil sludge based on radiant heating

It needs to be improved the conversion efficiency and stable operation of conventional pyrolysis with high-temperature flue gas heating (HFH). Herein, a new radiative heating (RH) pyrolysis method is proposed. Experimental studies are carried out on a self-made radiation pyrolysis pilot plant to investigate the effects of different factors (pyrolysis final temperature, residence time, and carrier gas volume) on product distribution. The results show that with the increase of pyrolysis temperature, the yield of the gas phase consistently increases, and the proportion of CH4 and H2 in the pyrolysis gas reaches 62.31% at 700 °C. The yield of the liquid phase increases and then decreases. The recovery rate of pyrolysis oil achieves 68.07% when the pyrolysis temperature is 600 °C with main components of ketones and unsaturated hydrocarbon compounds. The yield of the solid phase consistently decreases. The RH in this work generates more pyrolysis gas in the pyrolysis process and alleviates the effects of fouling layers on the continuous operation of the equipment which has guiding significance for the efficient resource utilization of oil sludge.

Construction of Shale Gas Oil-Based Drilling Cuttings Degrading Bacterial Consortium and Their Degradation Characteristics

Oil-based drilling cuttings (OBDCs) contain petroleum hydrocarbons with complex compositions and high concentrations, which have highly carcinogenic, teratogenic, and mutagenic properties. In this study, three highly efficient petroleum hydrocarbon-degrading bacteria were screened from OBDCs of different shale gas wells in Chongqing, China, and identified as Rhodococcus sp. and Dietzia sp. Because of their ability to degrade hydrocarbons of various chain lengths, a new method was proposed for degrading petroleum hydrocarbons in shale gas OBDCs by combining different bacterial species. Results showed that the bacterial consortium, consisting of the three strains, exhibited the highest degradation rate for petroleum hydrocarbons, capable of degrading 74.38% of long-chain alkanes and 93.57% of short-chain alkanes, respectively. Moreover, the petroleum hydrocarbon degradation performance of the bacterial consortium in actual OBDCs could reach 90.60% in the optimal conditions, and the degradation kinetic process followed a first-order kinetic model. This study provides a certain technical reserve for the bioremediation of shale gas OBDCs.

Valorization of oily sludge waste using biosurfactant-producing bacteria

Oily sludge generated by the petroleum industry is not only an environmental hazard, but since it contains crude oil too, it is a valuable resource as well. This study demonstrates a methodology for the valorization of the oily sludge that allows the recovery of oil fractions by the action of microbes producing surface-active metabolites. Two bacterial isolates were used in the study that were producing different biosurfactants, identified via FTIR analysis as well as through genomic mapping of the biosurfactant pathways using RAST, ANTISMASH 7.0, STRING databases. Serratia spp. AKBS12, produced a mono-rhamnolipid, while Acinetobacter spp. AKBS16, produced emulsan. Although recovery efficiency of both biosurfactants was similar, the recovery profile with respect to the class of hydrocarbons differed. The rhamnolipid produced by Serratia spp. AKBS12 extracted mono-chained paraffins and linear alkanes, while emulsan, produced by Acinetobacter spp. AKBS16 could extract heavier paraffins. The extraction procedure is simple and involves mixing the biosurfactant with oily sludge at a temperature of 30 °C with an incubation of 9 days. Sulphuric acid precipitation releases the oil trapped in the oily sludge. The study is the first step in developing user-friendly, innovative technologies that can be linked to the concept of a circular economy.

Biodesulfurization of Fossil Fuels: Analysis and Prospective

Biodesulfurization (BDS) of fossil fuels is a promising method for treating the high content of sulfur in crude oils and their derivatives in the future, attributed to its environmental-friendly nature and the technical efficient ability to desulfurize the organosulfur compounds recalcitrant on other techniques. It was found that the bioreaction rate depends on the treated fluid, targeting sulfur compounds, and the microorganism applied. Also, many studies investigated the operation conditions, specificity, and biocatalysts modification to develop BDS efficiency. Furthermore, mathematical kinetics models were formulated to represent the process. In this review, the previous studies are analyzed and discussed. This review article is characterized by a clear picture of all BDS's experimental, industrial, procedural, theoretical, and hypothetical points.

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.

Rapid effective treatment of waxy oily sludge using a method of dispersion combined with biodegradation in a semi-fluid state

Waxy oily sludge (WOS) from petrochemical enterprises has complex components and difficult treatment. Long-term large-scale stacking has seriously threatened human health and the ecological environment. In this paper, a new rapid and effective treatment method combining dispersion and biodegradation in a semi-fluid state was developed for the WOS. The degradation mechanism of the WOS in the bioreactor was preliminarily discussed. The component analysis results showed that the compounds with large molecular weight (M ≥ 282) in the WOS accounted for more than 50%. Among all microbial consortiums, the treatment effect of the consortium FF: NY3 = 9: 1 was the best for treating the crude oil in WOS, which was significantly different from that of a single strain (p < 0.05). Under the optimal nitrogen source NH₄NO₃ and the concentration of rhamnolipid, the developed high-efficiency microbial consortium (FF: NY3 = 9:1) could remove 85% of the total hydrocarbon pollutants in the 20 L semi-fluid bioreactor within 9 days. The degradation characteristics of WOS components in the bioreactor showed that the developed consortium has good degradation ability for n-alkanes (about 90%), middle- (77.35%)/long-chain (72.66%) isomeric alkanes, alkenes (79.12%), alicyclic hydrocarbons (78.9%) and aromatic hydrocarbons (62.78%). The kinetic analysis results indicated that, in comparison, the middle-chain n-alkanes, middle-chain isomeric saturated alkanes, alkenes, and alicyclic hydrocarbons were most easily removed. The removal rates of long-chain n-alkanes, long-chain isomeric saturated alkanes, and aromatic hydrocarbons were relatively low. The biological toxicity test showed that the germination rate of wheat seeds in treated waxy sludge was Significantly higher than that in untreated waxy sludge (p < 0.01). These results suggest that the new method developed in this paper can treat refractory WOS quickly and effectively. This method lays the foundation for the pilot-scale treatment of the semi-fluid bioreactor.

Experimental study on alkali catalytic gasification of oily sludge in supercritical water with a continuous reactor

Realizing the harmless resource utilization of oily sludge is urgent for petroleum industry and of great significance for environmental management. The treatment of oily sludge was investigated using supercritical water gasification (SCWG) with a continuous fluidized bed reactor. The effect of operating parameters on gasification efficiency and gas yield without catalyst was tested, and then the influences of catalyst type (K₂CO₃ and Na₂CO₃) and concentrations (1-8 wt%) were systematically studied. The results indicated that a medium mass flow ratio and low feedstock concentration were beneficial for gas production. Alkali catalyst improved carbon gasification efficiency (CE) prominently, and Na₂CO₃ showed better performance due to its better stability. A maximum CE of 95.87% was achieved when 5 wt% Na₂CO₃ was added at 650 °C, 23 MPa with 5 wt% oily sludge concentration. Besides, according to XRD patterns of solid residues, Na₂CO₃ was more stable than K₂CO₃ during SCWG. SEM-EDX results also revealed that more K was migrated into solid residues than Na. The analysis of pore structure demonstrated that alkali catalyst promoted the evolution of pore structure, resulting in higher specific surface areas and total pore volumes. Na₂CO₃ has a more substantial destructive effect on solid matrix, causing the matrix structure to collapse and inhibiting pore structure development. The FTIR spectra of solid products exhibited a lower content of carbohydrates and aromatic structures than the initial oily sludge. NH₄-N results demonstrated that SCWG was a potential green treatment process for oily sludge. This work can not only give an insight into the reaction mechanism of alkali catalytic gasification of oily sludge, but also help to guide the optimal design of reactor and the regulation of operating parameters.

[Applications of chromatography in giant complex drug-organism system]

Chromatography is an important branch of analytical chemistry that focuses on the separation and analysis of complex structures. Following more than 100 years of development and improvement, chromatography theory and technology have gradually become sophisticated. It has become a coalition of science, technology, and art. Recently, chromatography has been successfully used in combination with mass spectrometry, nuclear magnetic resonance spectroscopy, and atomic emission spectroscopy. Chromatography and the combination with other techniques has significantly improved the analysis of complex systems, such as the environment, food, petrochemicals, biological specimens, and medicine. As one of the oldest healing systems, Traditional Chinese Medicine (TCM) has served to maintain the health of people in China and worldwide for thousands of years. Therefore, it has become a core representative of traditional Chinese culture. In the past two years, TCM has been widely used to treat COVID-19, especially in patients with mild symptoms. Recently, Chinese government emphasized the inheritance and innovation of TCM and stepped up efforts to promote its modernization. TCM includes herbal medicine, acupuncture, moxibustion, massage, food therapy, and physical exercise, such as Tai Chi. In most cases, the patients are administered a mixture of TCM formulas containing more than two herbal medicines, resulting in a highly complicated compound mixture. There is no doubt that long-term clinical practices have demonstrated the safety and therapeutic effect of TCM. However, the compound mixture must be simplified to identify the active compounds. This is mainly because of the existence of carcinogenic compounds, pesticides, and heavy metal residues introduced through plantation and production processes. Moreover, enzymes within the human system generate further new compounds in response to the entry of the TCM containing thousands of components. Consequently, the complex TCM and organism systems interact with each other, constituting a giant complex drug-organism system. The analysis of this giant complex system is acknowledged as a key aspect in the modernization process of TCM. In the last 20 years, many studies have been conducted to screen and identify effective compounds in TCM. These effective compounds can be either the original compounds or new metabolic components generated in vivo. All these efforts are aimed at simplifying the components of TCM and elucidating the therapeutic mechanism. It is well known that chromatography can provide technical support for complex systems owing to its unique advantage of outstanding separation and analysis capabilities. Therefore, chromatography and its combination with other technologies have become mainstream technologies for promoting the compilation of molecular structure, information, digitalization, and modernization of TCM. This paper reviews the research and application of chromatography and combination technologies in a giant complex TCM formula-organism system. Furthermore, the authors briefly introduce and summarize the understanding, research ideas, and activities of the authors' team on the modernization of TCM. "Liang Guanxi" and "He strategy" are proposed as novel strategies for studying the giant complex drug-organism system. A distinguished technology integrated with mathematical model of causal relation, combined receptor chromatography, identification of chemical molecular structure and evaluating of pharmacological activities was established. It was successfully employed to determine the core effector-response substances of "Liang Guanxi" herb pairs in a giant complex drug-organism system. Subsequently, utilizing the proposed technology of Combination of Traditional Chinese Medicine Molecular Chemistry, the author's team designed and developed four series of innovative drugs. Inspired by the hundred years of chromatography history and thousands of years of TCM culture, the future development of chromatographic technology is expected. Furthermore, the mechanisms of TCM in medical healthcare, prevention, and treatment of diseases are likely be explained through chromatography, leading to a new strategy to realize the molecularization and digitalization of TCM, which is beneficial to the development of original new drugs.