With the increasing awareness of environmental protection and strict environmental standards, oil sludge, a dangerous solid waste containing petroleum resources, must be detoxified, reduced, and resourced. At present, for the treatment of oil sludge, domestic and foreign scholars and petrochemical-related enterprises have carried out a lot of research and formed a variety of oil sludge treatment technologies. Among them, the oil sludge treatment technology mainly includes: landfill disposal technology, curing treatment technology, biological treatment technology, profile control treatment technology, etc., in order to achieve the harmless, reduced and resource treatment of oil sludge.
First. Oil sludge landfill disposal technology
The oil sludge landfill disposal technology is a simple oil sludge treatment method. After the oil sludge is dehydrated and sealed, it is transported to the selected landfill for direct landfill. The treatment process is simple and rapid, the operation cost is low, and the operation management is simple, but the disadvantage is that the technology does not essentially treat the oil sludge, and the landfilled oil sludge not only occupies a large amount of land resources, but also fills in time. The buried oil sludge itself has a large amount of harmful components that are decomposed and will slowly infiltrate into the soil and surrounding groundwater, causing secondary pollution. Although the landfill has changed from an early natural attenuation type to a closed landfill, the above problems still exist. This technology is widely used in the early stage of oil sludge treatment at home and abroad. With environmental awareness and shortage of land resources, many countries have issued regulations prohibiting landfill disposal of oily sludge, but there are still some regions and countries. This method is still used to treat oil sludge.
Second, oil sludge solidification treatment technology
The process of curing the oil sludge is to transform the toxic and hazardous hazardous waste into a low-solubility, low-toxicity and low-migration substance, and to stabilize the toxic and harmful substances. The oil sludge solidification treatment technology is used in the early stage. To deal with radioactive sludge, the technology has developed rapidly in recent years. The oil sludge solidification treatment technology refers to the mixing and solidification of oil sludge with different kinds of solid agents, coagulants and additives, so that some properties of the oil sludge are irreversibly changed, thereby forming a solid body with better integrity.
The oil sludge solidification treatment technology is a mature treatment method capable of basically achieving harmlessness, simple treatment process and low operation cost, but the process uses a large amount of high-energy curing raw materials in the treatment process, after treatment The volume and weight of the cured product are greatly increased, and the curing agent has high requirements on the characteristics of the treated sludge. The current research mainly focuses on the development of the curing additive and the stabilization of the agent.
Third, the oil sludge biological treatment technology
The oil sludge biological treatment technology is to put special microbial strains into the oil sludge, so that the bacteria can grow and grow in the environment of oil sludge, and use this biological process to consume the organic matter in the oil sludge, and then to digestion into CO2 and H2O to achieve the purpose of removing all kinds of organic pollutants in oil sludge. The mechanism of the treatment mainly has two aspects: (1) A microbial flora with high-efficiency degradation ability naturally formed and screened and separated is added to the oil sludge; (2) By adding nutrients such as nitrogen and phosphorus to the oil sludge or mediating nutrient factors, the high-efficiency degradation activity of the microbial flora is stimulated by measures such as aeration, temperature control, and pH adjustment.
The main point of biological treatment of oil sludge is the selection and cultivation of the flora. Although this technology has many advantages, such as simple operation, energy saving, almost no need to add chemical reagents, and little environmental pollution, it also has its own limitations. , such as long processing cycle, unable to recover oil resources. The screening and cultivation processes of microbial flora are complicated, and the microbial community itself has limited tolerance to hydrocarbon organic matter, and is not suitable for treating high oil content sludge. Therefore, it is the future focus to screen the microbial flora with high ability to degrade.
Forth. Oil-sludge profile control technology
The oil sludge in the oilfield is produced from the stratum, and its composition includes water, crude oil, waxy, muddy sand, colloidal asphaltene, etc. This type of oil sludge has good compatibility with the formation, and the oil-sludge sludge profile control technology is based on “ From the viewpoint of the stratum and the stratum, the oil sludge is injected back to the bottom layer. This special refilling liquid needs to adopt some corresponding treatment methods, such as adding appropriate amount of emulsifier, suspending agent, etc. to enhance the solid particles of oil sludge. The effective suspension and extended suspension time are formulated into a uniform and stable profile control agent. The oil-containing sludge profile control agent is injected back into the formation. After entering the formation to a certain depth, the adsorption of the embedding dispersant by the formation rock and the release of the formation water cause the stable profile control agent system to start to decompose, and the mud sand particles in the profile control agent are adsorbed. After waxy and colloidal asphaltenes, particles with relatively large particle size are formed by adhesion and aggregation, and the pore size is reduced in the large pores, which makes the seepage resistance of the subsequent water injection greatly increase, effectively blocking the core of the formation, and thus greatly effect of water injection development has been improved and the oil recovery rate has been improved.
At home and abroad, it is very active in the research and application of oil-containing sludge profile control technology, and there are many oil fields that have been put into use. However, due to the large difference in the composition and characteristics of the sludge from different sources, different profile control agents need to be prepared for different sludges, and there are certain requirements for the treated sludge, for example, the oil content cannot be too high. Therefore, the application range of the technology is limited.