Treatment Of Oil Sludge Research Articles

Studying the Characteristics of Tank Oil Sludge

Oil sludge is one of the main pollutants generated by the oil industry. Due to serious pollution and increasing oil production, problems arise every year in the effective treatment of oil sludge. The current study examines the composition and physicochemical characteristics of oil sludge, as well as traditional and new methods for processing oil sludge. With the tightening of environmental protection requirements, oil sludge quality reduction, recycling, and harmless treatment technologies will become necessary in the future. The primary task was to determine the composition of tank oil sludge, separate it from mechanical impurities, and study the influence of ultrasonic treatment and subsequent atmospheric distillation on the extract. The separation of the concentrate and the composition of the tank oil sludge, using an extracted mixture of hexane and benzene, are considered. The use of modern SEM methods, elemental analysis, NMR analysis, IR, ultrasound, and GC–mass spectrometry made it possible to characterize the organic part of reservoir oil sludge and its distillation products. First, 300 g of tank oil sludge was preheated and mixed with 300 mL of solvent (hexane:benzene = 1:1). After mixing with the solvent, the result mixture was filtered. Then, it was placed in an ultrasonic bath and exposed to ultrasound at a frequency of 100 kHz for 30 min. After processing, it was extracted in a Soxhlet apparatus at a temperature of 65 °C to isolate the extract. The resulting extract was analyzed on a gas chromatograph with mass detection. The composition of the extract was as follows (in %): hexane—83.99; total hydrocarbon isomers—7.12; n-hydrocarbons—2.52; benzene—6.37%. At a temperature of 85 °C, the benzene yield was 65.85%. It has been established that the fractions obtained through the distillation of oil sludge at temperatures of 65–85 °C have improved dissolving capacity. It has also been shown that the use of these fractions promotes an increase in the content of hydrocarbon isomers by 12–13% in the extract composition.

The impact of solid particles and oil characteristics on the separation efficacy of oil sludge ultrasonic treatment

This study assesses the efficiency of ultrasonic treatment on oil sludge, with a specific focus on the impact of particle size and content, crude oil viscosity, and the interactions between crude oil and solid particles. The findings indicated that lower solids content correlates with increased oil recovery. For example, oil recovery rose from 15.09 % to 34.34 % as the solid content changed from 80 % to 40 % (200∼300 mesh). Furthermore, the study underscores the significant role of cavitation, particularly in the aqueous phase, and its dependency on fluid viscosity. Elevated viscosity raises the cavitation threshold of the medium, hindering the occurrence of cavitation effects and weakening the microjet. Acoustic energy attenuation during treatment should be emphasized, and both the propagation medium and the distance have an effect on the acoustic energy, which can be weaken by changing the ultrasonic irradiation method or by adjusting the size of the reaction unit. These findings provide valuable guidance for the ultrasonic treatment of oil sludge for optimizing crude oil recovery.

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.

Process analysis of H2 production from pyrolysis-CO2 gasification-water gas shift for oil sludge based on calcium looping

The treatment of oil sludge (OS) from petrochemical industry is a challenge. Traditional OS gasification process has the disadvantages such as low H2 yield and high CO2 emission. In this work, a novel pyrolysis-CO2 gasification-water gas shift process of OS for efficient H2 production based on calcium looping was proposed, which includes four stages: drying, pyrolysis, char gasification with recycled CO2 and water gas shift reaction for H2 production by in-situ CO2 capture using CaO. The pyrolysis-CO2 gasification-water gas shift process of OS was thermodynamically simulated by Aspen Plus. The effects of the mass ratio of steam/OS, temperature, mass ratio of CaO/OS, the proportion of CO2 reused on H2 generation and efficiencies of CO2 capture, energy conversion, and exergy were analyzed. The OS pyrolysis and CO2 gasification of char were also studied by experiment. Compared with direct steam gasification of OS process, H2 yield (0.32 Nm3/kg-OS) and efficiencies of energy conversion (36%) and exergy (32%) increase by 0.28 Nm3/kg-OS, 13.62%, and 17.16%, respectively. The novel process is promising for energy recovery from OS.

Simulation study on comprehensive thermal treatment of oil sludge based on Aspen plus

This article proposed an original comprehensive thermal treatment coupled with gasification and combustion (CGC) of oil sludge (OS), which was designed to produce hydrogen-rich syngas. Based on the experimental results of OS gasification with steam, the combustion characteristics of char from OS gasification were analyzed by thermogravimetric experiments under different heating rates of 10, 20 and 30 °C/min. The combustion process of OS gasification char can be divided into three stages, including water evaporation, volatile combustion and heavy component combustion. The average values of activation energy (E) obtained by Friedman, FWO and Starink methods were 89.98 kJ/mol, 147.61 kJ/mol and 143.09 kJ/mol, respectively. According to OS gasification and OS gasification char combustion experiments, the comprehensive thermal treatment process CGC of OS was simulated by Aspen Plus. The simulation results showed that increasing both gasification temperature and the mass ratio of steam to OS (SOS) could promote the hydrogen production. Considering energy consumption, the recommended OS gasification temperature, SOS and char combustion temperature were 800 ∼ 900 °C, 0.3 ∼ 0.5, and 900 ∼ 1000 °C, respectively, which could ensure full burning of char and reduce the generation of pollutants. The CGC process could reduce CO2 emissions by 44.2% from carbon flow analysis.

Unravelling the genetic and functional diversity of dominant bacterial communities involved in manure co-composting bioremediation of complex crude oil waste sludge

The present study aimed to characterize the bacterial community and functional diversity in co-composting microcosms of crude oil waste sludge amended with different animal manures, and to evaluate the scope for biostimulation based in situ bioremediation. Gas chromatography–mass spectrometry (GC–MS) analyses revealed enhanced attenuation (>90%) of the total polyaromatic hydrocarbons (PAHs); the manure amendments significantly enhancing (up to 30%) the degradation of high molecular weight (HMW) PAHs. Microbial community analysis showed the dominance (>99% of total sequences) of sequences affiliated to phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. The core genera enriched were related to hydrocarbon metabolism (Pseudomonas, Delftia, Methylobacterium, Dietzia, Bacillus, Propionibacterium, Bradyrhizobium, Streptomyces, Achromobacter, Microbacterium and Sphingomonas). However, manure-treated samples exhibited high number and heterogeneity of unique operational taxonomic units (OTUs) with enrichment of additional hydrocarbon-degrading bacterial taxa (Proteiniphilum, unclassified Micrococcales, unclassified Lachnospiraceae, Sphingobium and Stenotrophomonas). Thirty-three culturable hydrocarbon-degrading microbes were isolated from the co-composting microcosms and mainly classified into Burkholderia, Sanguibacter, Pseudomonas, Bacillus, Rhodococcus, Lysinibacillus, Microbacterium, Brevibacterium, Geobacillus, Micrococcus, Arthrobacter, Cellulimicrobacterium, Streptomyces Dietzia,etc,. that was additionally affirmed with the presence of catechol 2,3-dioxygenase gene. Finally, enhanced in situ degradation of total (49%), LMW (>75%) and HMW PAHs (>35%) was achieved with an enriched bacterial consortium of these microbes. Overall, these findings suggests that co-composting treatment of crude oil sludge with animal manures selects for intrinsically diverse bacterial community, that could be a driving force behind accelerated bioremediation, and can be exploited for engineered remediation processes.

Experimental investigation on smoldering combustion for oil sludge treatment: Influence of key parameters and product analysis

Oil sludge disposal has recently become a challenge because of its large reserves and high toxicity. Smoldering combustion is a new approach for organic waste treatment where organic waste is efficiently destroyed with minimal energy input. This study aimed to explore the feasibility of smoldering combustion for oil sludge treatment with a low filling medium addition ratio. The influence of four key parameters (i.e., the moisture content of oil sludge, filling ratio, grain size, and airflow rate) on the smoldering combustion characteristics was explored. Reducing the moisture content of the oil sludge and increasing the airflow rate improved the smoldering robustness of oil sludge. The smoldering process could remain self-sustaining across sand-to-oil sludge filling ratios of 1:3–2:1, and a sand-to-oil sludge filling ratio of 2:3 was the most favorable. The oil sludge mixed with the medium-sized sand has a high air permeability, which brought about the maximum treatment rate. Detailed post-treatment analyses of smoldering products were conducted to evaluate the extent of oil sludge disposal. Smoldering combustion could completely remove volatile petroleum hydrocarbons (C10–C40) in the oil sludge, with a harmless carbon-based black residue after incomplete combustion under certain limiting conditions. Most of the metal elements in the oil sludge were concentrated in solid products after smoldering. The smoldering treatment of oil sludge has great advantages in resource recovery, and half of the petroleum hydrocarbons in oil sludge can be recovered by off-gas condensation.

Genomic characterization of Enterobacter xiangfangensis STP-3: Application to real time petroleum oil sludge bioremediation

Sustainable treatment of petroleum oil sludge still remains as a major challenge to petroleum refineries. Bioremediation is the promising technology involving bacteria for simultaneous production of biosurfactant and followed by degradation of petroleum compounds. Complete genomic knowledge on such potential microbes could accentuate its successful exploitation. The present study discusses the genomic characteristics of novel biosurfactant producing petrophilic/ petroleum hydrocarbon degrading strain, Enterobacter xiangfangensis STP-3, isolated from petroleum refinery oil sludge contaminated soil. The genome has 4,584,462 bp and 4372 protein coding sequences. Functional analysis using the RAST and KEGG databases revealed the presence of biosynthetic gene clusters linked to glycolipid and lipopeptide production and multiple key candidate genes linked with the degradation pathway of petroleum hydrocarbons. Orthology study revealed diversity in gene clusters associated to membrane transport, carbohydrate, amino acid metabolism, virulence and defence mechanisms, and nucleoside and nucleotide synthesis. The comparative analysis with 27 other genomes predicted that the core genome contributes to its inherent bioremediation potential, whereas the accessory genome influences its environmental adaptability in unconventional environmental conditions. Further, experimental results showed that E. xiangfangensis STP-3 was able to degrade PHCs by 82 % in 14 days during the bioremediation of real time petroleum oil sludge with the concomitant production of biosurfactant and metabolic enzymes, To the best of our knowledge, no comprehensive genomic study has been previously reported on the biotechnological prospective of this species.

Co-combustion of Oil Sludge Char with Raw/Hydrothermally Treated Biomass: Interactions, Kinetics, and Mechanism Analysis.

Comprehensive thermochemical treatment (pyrolysis and combustion) is considered to be an efficient method for treatment of oil sludge (OS) or utilization as a heat source. However, combustion of oil sludge char (OSC), the byproduct from OS pyrolysis, is difficult and energy-consuming due to the high ash content and low heating value. In this study, co-combustion of OSC with biomass is proposed, aiming at the efficient thermal treatment with heat recovery. The thermal characteristics, kinetics, and interactive mechanisms of co-combustion of OSC with raw wood (RW) or hydrothermally treated wood (HW) employing thermogravimetric analysis were investigated. The obtained results indicated that RW blending with OSC resulted in negative interactions with decreasing the apparent activation energies (E) of RW, attributed to the inhibited diffusion of volatiles. The developed porous structure in HW effectively promoted volatile matter diffusion. Coupled with the catalytic support by metal oxides in OSC, HW blending yielded positive interactions during co-combustion despite the increased E. The results showed that diffusion models were the most efficient mechanism for OSC/RW combustion. However, chemical reactions were found to be the rate-determining steps for OSC/HW combustion. The catalytic effect of inorganic elements and their physical influence on heat and mass transfer can control the co-combustion performance of OSC and biomass. The findings could offer reference information for understanding OSC co-combustion and provide a basis for implementing and optimizing the co-combustion between biomass and ash-rich waste.

Experience in applying the technology of cavitation treatment of sunflower oil sludge for feeding ruminants

This paper presents research on evaluating the effectiveness of the technology of cavitation treatment of sunflower oil sludge intended for feeding ruminants. The evaluation on a general microbial content has been introduced, namely, quantitative and qualitative indicators of sunflower sludge before and after the cavitational processing have been described. During the experimental studies, the fact of a significant increase in digestibility of sunflower sludge after the cavitational processing by 21.1 % was revealed. At the same time, cavitation was not accompanied by any significant changes in the fatty acid composition of the feed, but it increased digestibility of a dry-matter in vitro due to an increase in bioavailability of the linoleic acid to 86.2 % versus 45.9 % in the native feed. The digestibility of other fatty acids either changed slightly, or decreased. The experiment shows the bactericidal and mycocidal effect caused by the cavitational processing. The effect caused by the cumulative jets of liquid when the cavitational microbubbles collapse caused the death of all microflora inherent to these types of products.

Thermodynamic model and kinetic compensation effect of oil sludge pyrolysis based on thermogravimetric analysis

Oil sludge is an organic solid waste in the petrochemical industry and improper treatment of oil sludge will cause environmental pollution. Pyrolysis is an effective way to realize its resource reuse. In order to understand the pyrolysis behavior and thermodynamic characteristics of oil sludge, four oil sludge samples from storage tanks were used as the research object, and pyrolysis experiments were carried out at heating rates of 5?, 10?, and 15? per minute under a nitrogen atmosphere. The kinetic parameters of pyrolysis of oil sludge are calculated by three equal conversion methods, Friedman method, Flynn-Wall-Ozawa method and Distributed activation energy model, and the most possible thermodynamic models for the main pyrolysis phase were analyzed and discussed by introducing the Malek method. The results show: high heating rate can promote the pyrolysis of oil sludge and in the pyrolysis stage, the apparent activation energy increases with the increase of the conversion rate. The apparent activation energy calculated by the Friedman method method is more reliable. The average apparent activation energies of the four oil sludge are 221.23, 84.71, 94.67, and 116.56 kJ/mol, respectively. The apparent activation energy and the pre-exponential factor are positively correlated, indicating that there is a kinetic compensation effect in the pyrolysis process. The thermodynamic models of the four oil sludge samples are all 3-D diffusion models, but their integral functions are different. The research results can provide theoretical support for the industrialization, harmlessness, and resource utilization of oil sludge pyrolysis.

Oil recovery from polymer-containing oil sludge in oilfield by thermochemical cleaning treatment

Polymer-containing oil sludge inevitably was produced during oilfield exploitation, which caused serious environmental pollution and resource waste. In this study, thermochemical cleaning method was firstly applied to treat oil sludge from Shengli Oilfield to solve environmental pollution, recover crude oil and achieve resource utilization. Through preliminary screening of cleaning agents, such as hexadecyl trimethyl ammonium bromide (CTMAB), sodium dodecyl benzene sulfonate (SDBS), fatty alcohol polyoxyethylene sulfate (AES), rhamnolipid, fatty alcohol ethoxylate (AEO-9), polyoxyethylene castor oil ether (EL100), polyoxypropylene polyoxyethylene propylene glycol ether (SP169), Tween 80, and Na2SiO3, three cleaning agents including Na2SiO3, SP169 and rhamnolipid were more effective than others. The optimized conditions of three cleaning agents were determined by measuring oil recovery rate. Afterwards, the ratio of Na2SiO3, SP169, and rhamnolipid in the mixed cleaning agent was 10:1:0.5. Under the cleaning conditions with an agent content of 1.1 %, a liquid-solid ratio (L/S) of 7:1, a temperature of 70 °C, a stirring speed of 400 rpm, a cleaning time of 60 min, the highest oil recovery rate could reach 98 %. Compared with a single cleaning agent, the average oil recovery rate was increased by 20 %. The mechanism of thermochemical cleaning treatment of oil sludge was further discussed. This research provided a theoretical foundation and technical support for the efficient treatment and resource recovery of polymer-containing oil sludge in oilfields.

Feasibility and analysis of oxidization of oil sludge by potassium persulfate based on principal component analysis

ABSTRACT A substantial amount of oil sludge is produced with the development of petroleum industry. In this study, the feasibility and mechanism of potassium persulfate oxidation are studied, and the key factors in the experiment are determined to efficiently deal with oil sludge of oil exploitation. Results show that the morphological changes of sludge before and after degradation are obvious, and the degradation rate can reach 37.81% under the following conditions: pH of 11, temperature of 55°C, sludge–water ratio of 1:2, dosage of 1.8 mmol/g, and time of 8 h. Further analysis showed that the degradation of oil by persulfate mainly relies on sulfate radicals and hydroxyl groups produced during oxidation. Principal factor and component analyses demonstrate that the pH is an important factor affecting the degradation rate. This research provides an effective method for the treatment of oil sludge.

Thermal decomposition kinetics analysis of the oil sludge using model-based method and model-free method

Oil sludge (OS) is one of the main waste in the petrochemical industry, and serious consequences can result from the improper disposal of this waste. Pyrolysis is an effective method to dispose of OS and to recover the high heating value combustibles from it. The pyrolysis of three OS samples was carried out in a nitrogen atmosphere at heating rates of 5°C/min, 10°C/min, and 20°C/min, respectively. The TG-DTG/DSC-DDSC curves show that the thermal decomposition of OS has been divided into 5 stages, and each stage has unique thermal decomposition characteristics. Two model-free methods were used to calculate the apparent activation energy at a conversion rate from 0.05 to 0.95, and based on 10 solid-state mechanisms of thermal decomposition, the model-based method was used to fit the thermal decomposition mechanisms exposed to the three heating rates. The results show that the high heating rate is beneficial for the pyrolysis of OS. The apparent activation energy varies irregularly with the conversion rate, and the apparent activation energy error calculated by the FWO method is smaller. For the three samples, OS-1, OS-2 and OS-3, the average apparent activation energies calculated by the FWO method are 40.39kJ/mol, 38.01kJ/mol, and 85.53kJ/mol, respectively. The mechanism function of OS thermal decomposition changed, and the process of thermal decomposition should be described by a three-step thermal decomposition model. During 140.48–331.88°C, the fitting correlation coefficients of the two-dimensional phase interfacial reaction mechanism under the three heating rates were all above 0.99. During 400.00–556.57°C, the fitting result of the three-dimensional nucleation and growth mechanism is better than fitting results of other models. During 583.82–676.60°C, the two-dimensional diffusion mechanism has a good fitting regression. Significantly, model-based method and model-free method provide effective and reliable thermal decomposition kinetics parameters and models as a theoretical support for optimization of OS industrial pyrolysis and treatment of OS.

Study on the Migration Characteristics of Sulfur and Nitrogen during Combustion of Oil Sludge with CaO Additive

Oil sludge (OS) is a typical hazardous waste from the petrochemical industry. Currently, the increasing ratio of high-sulfur crude oil worldwide that results in the growth production of OS with high sulfur content has drawn much attention. OS incineration with calcium-based additives has great potential to be an efficient and clean approach for the large-scale treatment of high-sulfur-containing OS. In this work, the migration characteristics of sulfur and nitrogen during OS combustion with CaO additives were investigated by an online thermogravimetric-mass spectroscopy-Fourier transform infrared (TG-MS-FTIR) spectroscopy system and a fluidized combustion reactor system, respectively. Results indicated that CaO significantly reduced the emissions of SO2 and NOx during fluidized combustion of OS, and the minerals in OS and CO2 in the flue gas affected the utilization efficiency of CaO additive. The sulfur fixation capacity by CaO decreased with the increase of combustion temperature and almost completely failed at 1100 °C. The capacity of CaO to reduce NOx emission increased first followed by a decrease with the increase of combustion temperature. Furthermore, CaO significantly promoted the conversion of HCN to other nitrogen-containing gases, which can promote the production of NO by the precursors (HCN and NH3) and the reduction reaction of NO to N2. To the best of our knowledge, there is still not an efficient and clean technology for large-scale treatment of OS in China. This study is helpful for the massive utilization of high-sulfur-containing OS.

Anaerobic Co-Digestion of Oil Sludge with Corn Stover for Efficient Biogas Production

The feasibility of anaerobic co-digestion for the utilization of oil sludge was verified using corn stover, to assess the influence of different raw material ratios and inoculum volumes on the properties of the generated gas. The anaerobic co-digestion method is a novel treatment technology, which may help to solve the problem of pollution by hazardous waste oil sand from the oil exploitation and smelting process. Results showed that single-oil sludge was not suitable for gas production as a digestive substrate due to the lack of organic materials and possible hazardous materials. With the increase in the quality of exogenous organic matter (corn stover), the cumulative gas production volume was proportional to the amount of corn stover material added. It was established that when the mass ratio of corn stover to oil sludge was 4:1, the gas production performance was optimal, with a cumulative gas yield of 1222.5 mL using an inoculum volume of 30 mL. The results of this study provide a fundamental parameter baseline for the treatment of oil sludge and the improvement of gas production efficiency.

STARx Hottpad for smoldering treatment of waste oil sludge: Proof of concept and sensitivity to key design parameters.

Growing stockpiles of waste oil sludge (WOS) are an outstanding problem worldwide. Self-sustaining Treatment for Active Remediation applied ex situ (STARx) is a treatment technology based on smoldering combustion. Pilot-scale experiments for the STARx Hottpad prove this new concept for the mobile treatment of WOS mixed intentionally with sand or contaminated soil. The experiments also allowed for the calibration and validation of a smoldering propagation numerical model. The model was used to systematically explore the sensitivity of Hottpad performance to system design, operational parameters, and environmental factors. Pilot-scale (~1.5 m width) simulations investigated sensitivity to injected air flux, WOS saturation, heterogeneity of intrinsic permeability, and heterogeneity of WOS saturation. Results reveal that Hottpad design is predicted to be successful for WOS treatment across a wide range of scenarios. The operator can control the rate of WOS destruction and extent of treatment by increasing the air flux injected into the bed. The potential for smoldering channeling to develop was demonstrated for the first time. Under certain conditions, such as WOS saturations of 80%, high heterogeneity of WOS saturations, or moderate to high heterogeneity of soil permeability, smoldering channeling was predicted to accelerate to the point that remedial performance was degraded. Field-scale simulations (~10 m width) predicted successful treatment, with WOS destruction rates an order of magnitude higher than the pilot-scale and treatment times increasing only linearly with bed height. This work is a key step toward the design and effective operation of field STARx Hottpad systems for eliminating WOS.

Current Trends on Oil Sludge Characterization, Toxicity and Treatment Systems

Oily sludge produced in the refineries contains various harmful contaminants and difficult to analyse Treatment of Petroleum Sludge is a major problem all over the world. More strict regulations are being imposed, which preservere the treatment technologies capable to deal with the hazardous pollutants. The inadvisable disposal of oil sludge leads to hazardous, due to the presence of high concentration of harmful substances. This paper presents critical review on the production, characterization, toxicity and biological treatment of petroleum sludge reported in various studies. Compared to usage and production of petroleum and oil based products, the pace of knowledge acquisition on treatment of petroleum and oil sludge is slower despite the availability of numerous treatment and remediation options. Also, the differences in performance of treatment methods and results reported from various literatures have been addressed to pave a way for a customized treatment solution to oil sludge contamination. There is a need to identify a cost effective solution through which toxic pollutants in the sludge is treated effectively with a potential to reuse as manure for cultivation of crops.

Production of carbon dioxide, methane and nitrous oxide gas emissions in biodegradation of waste oil sludge

Biodegradation Bioremediation of waste oil sludge through biodegradation using microorganisms still has an impact on the environment, because produces of gas emissions which causes to the global warming. The purpose of this study was to determine the production of carbon dioxide, methane, and nitrous oxide gas in biodegradation of waste oil sludge by using types of bioactivator from soil as the microbe inoculums sources was compost, mangrove and forest soil with adjusting the ratio of C:N:P of 360:60:1 to optimize the biodegradation condition. The results show that the addition of bioactivator on the treatment of waste oil sludge can increase the biodegradation process. The results show that the compost bioactivator treatment is 72 percent decrease in oil sludge, the forest soil bioactivator treatment of 58 percent and then the mangrove soil bioactivator of 46 percent. The observation of gas production obtained the highest concentration of carbon dioxide was produced on compost bioactivator treatment of 0.91 ppm on the 25 day, production of methane on compost bioactivator treatment was 0.66 ppm on the 25 day and production of nitrous oxide on the mangrove soil bioactivator treatment of 0.19 ppm on the 30 day; The decrease of hydrocarbon waste oil sludge and increased gas production are also associated with an increase in the population number of hydrocarbon degrading bacteria at all bioactivator treatments.

Synergistic effect of surfactant and alkali on the treatment of oil sludge

The oil sludge is considered as a hazardous waste, the improper disposal or insufficient treatment can pose a major problem to the oil production, transportation and processing processes, and may result in serious environmental concerns and human health risks. In the present study, washing treatment with a cleaning solution containing surfactant and alkali was investigated to remove the residual oil from the oil sludge obtained from Tahe Oilfield. The effects of the dosage of surfactant, cleaning temperature, stirring rate, stirring time and liquid-solid ratio on the performance in residual oil removing were analyzed. Sodium nonylphenol polyoxyethylene ether sulfate (AEOS) and alkali were used as the cleaning agents. The results show that the content of the residual oil in the sludge could be lowered from 14.3 wt% to 0.9 wt% after being washed twice under the optimum operation conditions with a 0.6 wt% AEOS and 3 wt% KOH solution for 30 min at 80 °C, a stirring rate of 210 rpm and a liquid-solid ratio of 3:1. Thermogravimetric (TGA) and infrared analyses confirmed that the oil components in the oil sludge can be mostly removed.