Oil refineries seek to optimize technological processes as much as possible, reducing the volume of unused production products. But the finer and deeper the processing of petroleum raw materials, the more dangerous is the waste that cannot be eliminated without third-party methods. One of the areas of recycling can be called the disposal of oil sludge as one of the most dangerous types of oily waste.
Oil Sludge Disposal Tasks
To date, the volume of oil sludge mixtures contained in refineries in Russia amount to several million tons. Basically, these materials are in storage facilities of oil producing, oil refining and petrochemical plants. In most cases, the generation of such waste occurs in the process of cleaning process equipment and communication channels for the delivery of oily products. The so-called oil sludge barns pose the greatest environmental hazard, at the sites of which local waste has been stored for a long time without recycling. Interacting with the atmosphere, they emit harmful fumes without the ability to clearly control the boundaries of their distribution. This situation contributes to the overflow of barns with oily waste, soil contamination and an increase in the area of chemical damage.
Accordingly, the primary tasks of the disposal of oil sludge include the processing of these wastes within the main production facilities. Moreover, utilization can be economically justified, since oil and sludge products contain up to 80% of hydrocarbons that can be used as a fuel and energy resource. Another thing is that it is not always technologically possible to rationally process oil-containing waste with the extraction of financial benefits in principle.
Oil sludge collection
The initial stage of work with various types of oil sludge. The use of aggregates, mechanisms and devices with the help of which waste is removed from surfaces, from streams and other oil and water masses is provided. The fees are based on the methods of absorption of spilled oil products at the expense of auxiliary means, including the use of emergency equipment. Next, preparations are made for the disposal of oil sludge, during which an analysis of the composition of the collected materials is performed. Specialists carry out thorough and multifactorial monitoring, which allows evaluating the qualitative characteristics of the sludge, its composition and possibilities for future processing in one way or another.
Oil sludge removal
Waste is transported from collection facilities to temporary storage or disposal sites. To perform this task, special vehicles are used - a suction truck. Using this technique, sludge is pumped and removed. From the basic characteristics of sludge pumps, one can distinguish a capacity of 7 to 10 m 3 (on average), a pumping depth of about 7-8 m and a chassis based on Kamaz. Now it’s worthwhile to consider in more detail the methods of disposal of oil sludge at the facilities of their final delivery.
Hydrotreatment disposal
The method involves performing a heating operation, in which there is a sedimentation of waste with subsequent separation into separate components of the composition. Separation processes are initiated as a result of desorption of oil products contained in the waste. The fact is that the sludge is characterized by a complex physicochemical structure, which not only oil compounds can make up. Centrifugal installations for the disposal of oil sludge in the form of centrifuges and decanters with high acceleration allow the separation of oil components, mechanical and aqueous impurities. The hydrocarbon phase can be returned to further use, and in a purified form without the need for filtration.
Physicochemical Processing
In this case, drum separators are used in which the extraction of the target product is organized. In other words, there is a polar dissolution of the direct oil product and the active substance added to the material. The process is quite effective, but complicated. In particular, regularly there is a need to replace individual mechanical parts of the processing complex. As a consumable, filters and the solvent to be regenerated are used. As for the pluses, the equipment for the disposal of oil sludge like skimmers makes it possible to perform complex waste disposal through flotation treatment. Also, drum separators are successfully used in the elimination of oil spills on water surfaces.
Biochemical disposal of oil sludge
It is supposed to carry out the method of artificial decomposition of petroleum products using oxidizing microorganisms. An active microorganism is placed in a special tank with the waste placed in it, which also provokes the processes of reclamation. Biochemical disposal of oil sludge has its advantages in the form of accelerated purification of the target product and high reducing ability in relation to contaminated soil. But this method also has weaknesses, which include:
- Positive recovery, decomposition and reclamation processes affect only a small fraction of the organic oil components.
- Achieving tangible results is possible only after prolonged oxidation by microorganisms.
- Active biochemical processing requires the creation of certain temperature conditions in a narrow range.
- The method is allowed for use only in the case of materials having a low content of petroleum products. For this reason, it is often used for the final treatment of sludge after a significant decrease in the content of petroleum materials in the composition by other methods.
Thermal disposal of oil sludge
A wide group of methods involving the thermal processing of waste with the subsequent formation of degradation products in the form of carbon and hydrogen. The simplest technology for implementing this principle is the disposal of contaminated soils as a result of organized burning. But due to low productivity and high cost, this method has been replaced by oil sludge pyrolysis - waste disposal by deep oxygen-free burning with the conversion of oil raw materials into liquid and gaseous products that can be used as fuel.
Current problems of oil sludge disposal
Despite connecting high-tech equipment to the processes of oil-containing waste recycling, many difficulties remain for enterprises working in this field. Among the most sensitive issues are the following:
- Oil sludge has a complex composition. Often such wastes include about half of the elements of the periodic table, which complicates the process of selecting and applying optimal disposal tactics.
- High cost of processing. Depending on the technology for the disposal of oil sludge, the price per ton of material served varies from 7 to 20 thousand rubles. This applies only to the main processing process, but a significant addition to the estimate is provided by the intermediate stages of servicing mixtures.
- Environmental harm from the recycling methods themselves. Although the use of petroleum product recycling technologies in itself is oriented towards improving the environmental background, improper use or incorporation of cheap and outdated methods can aggravate environmental pollution.
Conclusion
The current practice of oil waste management in Russia has a more differentiated approach without a comprehensive solution. This is largely due to the technological backwardness of enterprises whose activities are associated with the formation or use of oil sludge. For this reason, state programs for the disposal of oil sludge are increasingly being introduced, within the framework of which it is planned to disseminate innovative hazardous waste treatment plants. Their developers focus on combining the tasks of improving the environmental situation from the point of view of state policy and obtaining economic benefits for oil refineries. In addition, ensuring the safety and rationalization of the use of natural geosystems is not the least among the goals of such programs.