Modification technology for separation of oily sludge

Based on the analysis of the properties of oily sludge samples,the effect of modification parameters,such as liquid to solid (L/S) ratio,agitation temperature,agitation intensity,agitation time and pH on the modification of oily sludge was investigated with the content of oil remnants in dry sludge as a reference index. Remixing experiments were carried out according to a simplex-lattice design,where Sx4056 was used as the demulsifier,petroleum sulfonate as the surfactant and sodium silicate (Na2SiO3) as the dispersant. The surface modification reagent formulation was optimized by a regression equation on the modified effect and based on the amounts of surface modification reagents. The results show that the content of the oil remaining in dry oily sludge is 0.28% of 10.15% oily sludge,when the reagent concentration rises to 3.5 g/L under the optimum experimental conditions.

Characterization of oil component and solid particle of oily sludge treated by surfactant-assisted ultrasonication

The ultrasonic technique has been demonstrated to be a promising method for the disposal of hazardous oily sludge.However,the separation of oil from the surfaces of the solid particles is still difficult due to the strong interaction between the oil and solid particle.In this study,three types of surfactants were used to assist the ultrasonic treatment of oily sludge.The oil component,surface composition,and structure of the solid particle were determined.The results showed that different surfactants had different oil removal abilities.In the three surfactant-assisted sonication systems,the oil removal rate increased during the starting reaction period and then decreased with longer sonication time.The results of four components analysis suggested that surfactant easy to be ionized in water posed a better removal effect on resins,while the amphiphilic surfactant preferred saturates,aromatics and asphaltenes.The morphology analysis indicated that particle size was shattered into smaller ones by the ultrasonic process,and the wettability of the solid surface also changed during this treatment.The characterization of the oil component and solid particle during surfactant-assisted ultrasonication treatment will help to better understand the separation of oil from oily sludge and improve the oil recovery efficiency from oily sludge.

Application of hydrophobic ionic liquid [Bmmim][PF6] in solvent extraction for oily sludge

In this study, an ionic liquid(IL), 1-butyl-2,3-dimmmethylimidazolium hexafluorophosphate([Bmmim][PF6]),was used in combination with a composite solvent of methyl acetate and n-heptane to enhance the oil extraction from oily sludge. The oil recovery increased by approximately 15% compared with that of solvent extraction without [Bmmim][PF6] at the optimal ratios of IL to sludge and solvents to sludge, which were at 2:5(M/M) and 4:1(V/M), respectively. The saturate, aromatic, resin and asphaltene(SARA) analysis revealed that the recovery of resins and asphaltenes was increased by 14% and 38%, respectively, in the solvent extraction with the addition of [Bmmim][PF6]. [Bmmim][PF6] maintained a good performance after its reuse four times. The addition of[Bmmim][PF6] changed the adhesion forces between oil and soil. The IL-assisted solvent extraction procedure followed the pseudo second-order kinetic model, while the unassisted solvent extraction procedure followed the pseudo first-order kinetic model. The results also demonstrated that [Bmmim][PF6] decreased the solvent consumption by approximately 60% each time. Additionally, [Bmmim][PF6] can be easily separated. The results suggested that enhancing the solvent extraction with this IL is a promising way to recover oil from oily sludge with a higher oil recovery rate and lower organic solvent consumption than those with the unassisted solvent extraction method.

Solid- liquid phase separation and resource recycling study for waste rolling oily sludge

On the basis of the characteristics of a highly emulsified solid-liquid phase （fine particles, sticky consistency,black color, and low reuse ratio）, waste rolling oily sludge has been a focal problem in the steel industry. In this article, a solid-liquid phase separation and resource recycling process was described, with pilot test results showing that flocculation-sedimentation is an effective pretreatment, and that the filtration-coagulationvacuum distillation process is simple and feasible with a 53.5% recovery rate for regenerated oil that is qualified for return to the roiling production line. Then,solid phase oil-sludge was extracted by solvents with a 77% metal resource recovery rate and a wide utilization range. Finally, according to the experimental results, a set of feasibility plans for a 50 t/a waste rolling oily sludge solid-liquid separation and resource recycle project was designed, with the expectation of 50% regenerated oil yield, 70% solid metal resource recovery, and a 2. 5-year investment payback period.

Dissipation of polycyclic aromatic hydrocarbons in crop soils amended with oily sludge

Oil fields present a potential ecological risk to nearby farmland soil. Here we present a new method designed to evaluate the ability of winter wheat(Triticum aestivum) to contribute to the dissipation of polycyclic aromatic hydrocarbons(PAHs), which are priority pollutants in soils contaminated by oily sludge. The influence of different doses of oily sludge on the dissipation of PAHs was studied along with individual PAH profiles in soils after different periods of plant growth. Five soil samples were artificially contaminated with different percentages of oily sludge(0 %, 5 %, 10 %, 15 % and 20 %). Winter wheat grew in the oily sludge–amended soils for 265 days.PAH content in the soils was monitored over the course of the study. The rate of PAH dissipation is related to the properties of different PAHs, period of winter wheat growth, and oily sludge application dose. Analysis for treated soils indicates that the dissipation of PAHs increased significantly over the first 212 days, followed by minimal changes over the final 53 days of treatment. In contrast, PAH dissipation slowed with increasing oily sludge application. For each PAH, the experimental results showed a significant compound-dependent trend. Winter wheat in the present study significantly enhanced the dissipation of PAHs in oily sludge–contaminated soil.

Theoretical study on the pressurization characteristics of disc-seal single screw pump used in high viscosity oily sludge conveying field

The disc-seal single screw pump(DSSP)used in the field of high viscosity oily sludge transport has a huge advantage.However,there is no research on the pressurization characteristics of the DSSP at present,which makes its application limited.In view of this,the pressurization process mathematical model of the DSSP was established based on the geometric model of the pump.By using this model,the pressurization characteristics of DSSP and the influence of working parameters on the pressurization process were studied combined with the principle of back-flow pressurization.Analysis results show that the instantaneous pressurization process could be realized mainly depending on the reflux pressurization from the outlet chamber to the pressurization chamber when the screw rotor rotating angle is located at-5°to+5°.The pressure in the pressurization chamber will increase with the increase of working parameters which include inlet pressure,outlet pressure,screw rotation velocity and dynamic viscosity of fluid medium in the area of flow-back pressurization.The screw rotation velocity and the viscosity of the conveying medium have significant effects on the peak pressure in the pressurization chamber,and the peak pressure in the pressurization chamber is proportional to the screw rotation velocity and the dynamic viscosity coefficient of the conveying medium.The proportional coefficient between the peak pressure and the screw rotation velocity is 6.29×10~4.The proportional coefficient between the peak pressure and the dynamic viscosity of the conveying medium is 6.28×10~6.

Oil Phase Molecular Compositions of Oily Sludge Using Mass Spectrometry

Oily sludge was recognized as a kind of hazardous wastes,so recycling its high content of petroleum hydrocarbons can contribute to the clean environment.In this study,oily sludge was subjected to continous ultrasonic extraction with an acetone/carbon disulfide(CS2)mixture solvent.Fourier transform infrared spectroscopy(FTIRS),gas chromatography/mass spectrometry(GC/MS),and Quadrupole exactive Orbitrap mass spectrometry(QPEOTMS)were used to analyze the oil phase compounds from oily sludge.The n-alkanes ranging from C8 to C31 hydrocarbons were detected in oil phase.Compared with the analysis results of GC/MS,more heteroatom-containing compounds(HACOCs)of oil phase such as O3,O4,N2Oo and N3Oo(o=0—3)could be detected by using the QPEOTMS analysis.Overall,these findings will potentially contribute to the clean and efficient utilization of oily sludge.

Investigating the co-combustion characteristics of oily sludge and ginkgo leaves through thermogravimetric analysis coupled with an artificial neural network

The co-combustion characteristics of oily sludge and ginkgo leaves(GL) in an oxy-fuel atmosphere are investigated via thermogravimetric analysis coupled with an artificial neural network. The combustion characteristics of blends improve as the GL mass ratio increases. The interaction indices used to evaluate the interaction between the two solid combustibles present a complex nonlinear relationship in different stages. The Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods are used to calculate the activation energy of the blends, which increases with an increase in the oxygen concentration, in different atmospheres. Compared with the radial basis function, the backpropagation neural network performs better in predicting the combustion curve of the blends.

Bioremediation and detoxification of real refinery oily sludge using mixed bacterial cells

Anaerobic biotreatment of real field petroleum refinery oily sludge(PROS)was investigated under using four different organic loads(OLs)in the order ofOL4>OL3>OL2>OL1,in bench-scale bioreactors.The bioremediation of raw PROS was carried out using mixed culture biocatalyst without chemicals addition or any type of pretreatment.The results revealed a potential performance of the used biocatalyst dominated by Pseudomonas aeruginosa(class:Gammaproteo)and Staphylococcus spp.(class:Bacilli)achieving significant removal of chemical oxygen demand(COD)and total petroleum hydrocarbons(TPH).The highest organic removal rate was recorded in OL4 followed by OL3,0L2,OL1,respectively indicating a positive relationship between the percentage removal of organics and their content.Maximum removal efficiencies of 96.7%and 90%were observed for COD and TPH,respectively in OL4 within 14 days only.Analysis of polycyclic aromatic hydrocarbons(PAHs)demonstrated that acenaph-thylene and phenanthrene exhibited the maximum removal efficiency(almost complete)among the 8-priority PAHs tested in this study.However,the overall degradation of PAHs in the oily sludge was 83.3%.

Chemical reactions of oily sludge catalyzed by iron oxide under supercritical water gasification condition

Supercritical water gasification is a promising technology in dealing with the degradation of hazardous waste,such as oily sludge,accompanied by the production of fuel gases.To evaluate the mechanism of Fe_(2)O_(3) catalyst and the migration pathways of heteroatoms and to investigate the systems during the process,reactive force field molecular dynamics simulations are adopted.In terms of the catalytic mechanisms of Fe_(2)O_(3),the surface lattice oxygen is consumed by small carbon fragments to produce CO and CO_(2),improving the catalytic performance of the cluster due to more unsaturated coordination Fe sites exposed.Lattice oxygen combines with*H radicals to form water molecules,improving the catalytic performance.Furthermore,the pathway of asphaltene degradation was revealed at an atomic level,as well as products.Moreover,the adsorption of hydroxyl radical on the S atom caused breakage of the two C-S bonds in turn,forming·HSO intermediate,so that the organic S element was fixed into the inorganic liquid phase.The heteroatom O was removed under the effects of supercritical water.Heavy metal particles presented in the oily sludge,such as iron in association with Fe_(2)O_(3) catalyst,helped accelerate the degradation of asphaltenes.

Strontium ferrite powders prepared from oily cold rolling mill sludge by solid-state reaction method

Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.

Co-pyrolysis of oil sludge with hydrogen-rich plastics in a vertical stirring reactor:Kinetic analysis,emissions,and products

Pyrolysis is an effective method to treat oily sludge(OS)due to its balance between oil recovery and nonhazardous disposal.However,tank bottom OS contains a high content of heavy fractions,which creates obstacles for pyrolysis due to the high activation energy.The incomplete cracking of macromolecules and secondary polymerization decreases the oil quality and causes coking during the operation process.This study introduced polyethylene(PE)into OS to deploy the H/Ceff ratio of feedstocks for pyrolysis A strong interaction between OS and PE during copyrolysis could be observed from the TG/DTG curves.PE tightly participated in OS degradation,while OS also promoted PE degradation at high temperature.Apparent pits were generated in solid residues from copyrolysis,which was attributed to the uniform and violent gas release.In addition to HCN,other nitrogenous and sulphurous pollutants were inhibited.Accordingly,more gas products were attained after PE addition with more value-added compositions of alkanes and alkenes.Although the oil yield decreased after PE addition,the oil products from copyrolysis possessed higher heating values and higher contents of light fractions with short chains as well as paraffins.Consequently,copyrolysis of OS and PE significantly improved the pyrolysis process and resulted in high oil quality.