Introduction:
One of the branches of petroleum biotechnology that has been commercialized and can be seen today in the list of services provided by companies active in the field of environmental issues is the biological purification of waters and soils contaminated with petroleum compounds. The release of petroleum and its products into the environment, the continuation of life. Many organisms living in terrestrial and aquatic ecosystems are threatened, and by polluting underground water, it poses a serious threat to human health, and by destroying the habitat of useful species, it imposes its negative effect on the economy of sectors such as agriculture and fisheries. Iran Considering having 58/8% of the world’s oil resources and petrochemical production of about 30 million tons per year and having the second place in the world’s gas reserves, the existence of more than 25,000 km of oil and gas transmission lines, having more than 1,300 refueling transfer stations and 10,000 The tanker carrying oil and oil products is very vulnerable to contamination of water and soil with oil products. These phenomena should be carefully investigated and their role in energy transfer should be evaluated [1].
1- Oil release
Oil spill is the harmful release of oil into the environment, mostly water, which sometimes destroys flora and fauna in the environment. Oil is the most important general pollutant in the oceans. More than 3 million tons of petroleum products enter such environments (oceans) every year and are polluted by oil. Most of the oil pollution in the oceans is caused by land and coastal plains. Runoff and waste water from cities, industries and polluted rivers carry oil to the oceans. Ships and oil transportation by them are the third cause of oil pollution in the oceans. Oil pollution happens when the tankers of the ships are broken or their balance water enters the oceans. Unfortunately, one of the side effects of storing and transporting oil and petroleum products is the side effects of oil spills. The emission and pollution caused by it is very difficult and difficult for the cleanliness of marine environments.
A type of oil pollution and release that is often discussed and thought about is its release due to marine and international accidents of oil products to marine environments caused by human activities. (Drilling, production industries, storage, transfer, management of petroleum waste materials) in these ways, petroleum materials are suspended and floated on water environments and are transported in the form of separate masses by the wind and the activity of waves and tides. Oil release can be partially controlled by chemical dispersants, ignition process, mechanical absorbers (floating dams). Of course, these processes themselves have destructive consequences on coastal ecosystems. Among the ways of oil release, for example, the following processes can be mentioned: explosion of oil wells, leakage and breakage of oil pipelines, accidents of oil-carrying ships, filling and overloading of oil tankers and oil spills from them, and draining the bottom of the oil tanks of ships. .
Perforation of underground storage tanks and oil-contaminated runoff that enters the rivers and then reaches the seas and oceans from the streets and city parking lots along with the rainwater is also one of the levels of water environment pollution. Oil emission and pollution control institutions are very effective in preventing, limiting and purifying industrial oil emission.
Characteristics and features of oil release:
The major release of crude oil and its by-products in the sea occurs during their transportation by oil tankers. Loading, unloading and blasting operations are also factors of oil release. When oil enters the water environment, it changes and transforms in different ways, including physical, chemical and biological processes, and affects the water environment. The process of physical and chemical changes starts as soon as the oil enters the water environment. These stages include: evaporation, expansion, emulsification, decomposition and corruption, air and sea exchanges and sedimentation. Chemical oxidation of some oil compounds is also often done with the help of sunlight. The decomposed compounds of these processes include: floating tar-like masses, dissolution and atomization of hydrocarbon materials in the water column and surfaces, and materials deposited on the seabed.[2]
The biological process takes place slowly along with the physical and chemical processes. The most important biological processes are: decomposition of petroleum substances by micro-organisms and conversion to carbon dioxide or organic substances in the intermediate phase, oxidation, transport to high water levels by large organisms and metabolites, storage and discharge.
Types of released oil:
Crude oil and its by-products are a highly complex compound. Since the fate of petroleum substances in aquatic environments depends on their compounds, it is necessary to know the substances and types of compounds present in petroleum in order to know the fate of petroleum substances when they are released into water.
Normal type:
Gasoline or gasoline 30%, kerosene 10%, light oil extract 15%, heavy oil extract 25%, oil waste more than 20%.
Classification based on molecular:
Paraffin (alkanes) 30%, naphthalene (cycloalkanes) 50%, aromatic compounds 15%, (nitrogen, sulfur and oxygenated compounds) 5%.
The fate of oil in marine environments:
Once oil is released into the sea, it usually begins to break down as it spreads into the marine environment over time. This dispersion is the result of a number of physical and chemical processes that change the compounds formed in the oil when it is released. The set of processes is generally known as weathering.
Sedimentation/burial: some heavy refined products have high density and as a result it easily settles in fresh water or shallow waters. Sedimentation often occurs due to the mixing of deposited particles and oil organic materials based on the weight of oil stains. Flowing waters often carry suspended materials that provide suitable conditions for sedimentation.
Spreading: The spread of crude oil in water is perhaps one of the most important processes of oil diffusion. Regardless of the chemical properties of oil, the amount of material spread is affected by wind, waves and water currents. Under the influence of hydrostatic properties and source forces, oil expands rapidly and this expansion reaches an average thickness of less than 0.3 mm in 24 hours. The layers of oil do not become continuous and continuous unless they are condensed by the wind and the wave takes them to the islands and beaches, where the layers of oil, due to the stillness and lack of movement resulting from being stuck in the rocks on the coasts of the islands, are joined to them by thinner layers. It forms an active surface of petroleum materials.
Evaporation: Evaporation and decomposition are two important processes of decomposition of crude oil released in water. Oil composition, regional and physical conditions of the place of release, wind speed and movement, air and sea water temperature, turbulence and intensity of solar radiation all affect the rate of evaporation of petroleum hydrocarbons. . Evaporation alone removes about 50% of the hydrocarbons in the average crude oil released into oceanic environments. The loss of volatile hydrocarbons increases the density, movement and viscosity of oil. When many volatile hydrocarbons have evaporated, the viscosity of oil increases and this phenomenon is due to weathering of the surfaces and their reduction into smaller parts. Mixing these small parts together increases the level of water that is contaminated.
Photooxidation: natural sunlight in the presence of oxygen can convert a large number of petroleum hydrocarbons into hydroxy compounds such as aldehydes and ketones and finally into molecules with lower weight such as carboxylic acids as hydrophilic compounds. This process changes the behavior and solubility of oil in the sea. In this process, petroleum substances chemically react with oxygen molecules in the presence of sunlight and are either transformed into soluble substances or into stable substances called TAR. This process is supported by sunlight and the intensity of oxidation depends on the type of oil and how it is exposed to sunlight.
Dispersion (diffusion): Dispersion is the combination of oil-in-water emulsion due to the adhesion of bubbles and small oil particles in the water column and surfaces. As soon as oil comes into contact with water, it quickly disperses in the form of an emulsion due to its oily state. This happens in the first 10 important hours of oil release in the sea.
Degradation: Degradation is another important physical process of the behavior and fate of oil in water. This process occurs due to the contact of sunlight and decomposition agents with oil molecules suspended in water and is one of the important physical and chemical processes and behaviors of oil in water.
Biodegradation: This process affects the fate of petroleum substances in aquatic environments. This process includes: microbial breakdown, digestion and ingestion of oil by zooplankton, with uptake and breakdown by marine invertebrates and aquatic vertebrates. Microorganisms have the ability and aptitude to oxygenate petroleum hydrocarbons and related compounds naturally. Microbial degradation rates vary with crude oil chemical composition, microbial populations, and many environmental conditions.
Emulsification: the process by which oil becomes suspended in sea water and remains suspended in the water in the form of oily spots. This happens by physical mixing of materials and turbulence in seawater.
Combating measures against oil spills:
1) Fighting at sea, reactive techniques when the oil is still suspended in the sea and has not reached the coastline.
2) Fighting in the land and in the land, reactive techniques when the oil is very close to the coastline or the seashore.
3) Prevention at sea, measures, decisions and operations that can be considered regarding the transportation and transfer of oil at sea.
4) Prevention on land, preventive measures that can be taken to avoid and prevent the discharge of oil from land areas into marine environments.
Biological technology in the treatment of sludge (sediments) of petroleum materials and the release and pollution of oil:
Oil sediments are usually the result of the discharge of oil from refineries into the sea, which includes toxic compounds that are considered serious risks for the ecology of the sea. All forms of aquatic life are dangerously affected, so that infected fish pose fatal health risks when consumed by humans. Although biotechnology has shown that certain species of bacteria and fungi can usually preserve the marine environment after pollution to some extent by decomposing oil materials and breaking hydrocarbon rings, which are part of the most important oil polluting compounds. Therefore, for the oil cleaning process to be effective in the sea, microorganisms (microorganisms) must be able to stand and be stable in the sea environment. For example, they need a high concentration of salt and salinity to grow and reproduce at low temperatures to survive in the marine environment contaminated with petroleum. Perhaps this requires the use of some modern and up-to-date biological technology techniques to introduce these characteristics and specifications for better decomposition of oil in the sea by organisms such as bacteria. Special marine microorganisms can use complex hydrocarbon compounds in the sea as energy and in the form of energy. This process itself can help in cleaning the oil and spreading its pollution in the sea. These bacteria have a special structure and this (decomposition of oil in the sea) is difficult and sometimes impossible for other organisms. Genetically modified organisms are suitable for breaking down released petroleum substances and also multiple petroleum compounds. An example of these bacteria is ALKANIVORAX BORKUMENSIS, which can provide the basis for the decomposition of oil in the sea for other organisms. [3]
2- Oil release control:
Oil spills occur when there is a problem in oil wells or when oil transmission lines explode or from oil spills during oil transport vessel accidents. The largest amount of oil pollution is caused by transportation tankers. (transportation 60%, industry 17%, human economic activity 12%, coastal power plants 6% and other cases). Considering that oil release occurs in different conditions, different methods should be used to control it.
Floats (mechanical dams): These floats are used as floating obstacles on the water to clean oil from water sources and to prevent its spreading and leakage.
Skimmers: Skimmers are small boats that can remove oil from water. Skimmers in which pumps are used, use suction power to separate and clean oil floating in water.
Absorbents: They are sponges that can collect and clean oil.
Dispersing materials: used to break and divide petroleum materials into smaller amounts and move and disperse these materials from the upper surface of the water (superficial).
Bioremediation: Used to speed up the process of biodegradation of oil after its release. In this process, bacteria or other living organisms and microbes in the sea come into action and help the oxidation of oil.
The effects of crude oil on the living system of the sea:
Spilled oil is a serious threat to freshwater and marine environments that affects resource levels and a wide range of subsets of organisms that are related to the complex food chain that includes humans. Spilled oil can damage the marine environment in various ways, including: physical destruction that directly affects wildlife and their habitats (such as damage to the body covering of birds or marine mammals). Also, oil toxicity by itself can severely poison and destroy organisms. The intensity of released oil depends on several factors such as the physical properties of oil, the type and type of oil, as well as the natural activities of water flow (waves, tides). [4]
The biological consequences of oil release and its effects on the living environment are:
1) Risks for humans who use contaminated marine food ingredients.
2) Reducing fishing resources or harming wildlife such as sea birds and marine mammals.
3) Reduction of the aesthetic values of the sea and beaches caused by oil-polluted beaches.
4) Changing the marine ecosystem through the reduction of animal species along with the reduction in diversity and their reproductive power.
5) Change in habitats, delay or prevention of animal colonization for communities and breeding.
Investigating the role of plants in refining soils contaminated with petroleum hydrocarbons
Investigating the phytoremediation ability of three plants: barley, alfalfa and clover, the plants were grown in pots containing soil contaminated with diesel fuel (at concentrations of 0, 25, 100, 500, 3000 and 40000 ppm) and after a period of 120 days, the residual concentration of the pollutant It is extracted from the soil and measured by a gas chromatograph. Based on the obtained results, the average removal percentage for barley is 86%, for alfalfa and clover is about 81% and 80%, respectively, and in the control environment (no plant) is about 75%. The initial concentration of the pollutant has an effect on the percentage of germination, dry weight of the plants and consequently on the reduction of the concentration of the pollutant by the plant. Considering the proof of the role of plants in the purification of soils contaminated with petroleum substances and also considering that this method can be easily implemented in places with low to medium pollution, it can be considered as a suitable method to remove such pollutants.
Studying the effect of alfalfa on soil contaminated with light crude oil
Contamination of soil with crude oil or its derivatives can cause damage to the environment, causing the destruction of the microbial and plant population of the soil. However, some microorganisms are able to use soil polluting oil compounds as food and reduce soil pollution. Some bacteria have a high ability to reduce or remove oil pollution from the soil, that’s why they are used in the biological removal of oil. The use of plants in reducing oil pollutants has been taken into consideration today, which is called plant remediation. Among plants, grasses and legumes are more important. In the phenomenon of phytoremediation, the cooperation between plant roots and soil microorganisms is carried out in order to remove pollution, so that plant root secretions provide a suitable environment for the growth and reproduction of soil microorganisms (rhizosphere environment), which can help to remove oil contamination by microbial population. Also, the root of the plant can absorb some of the oil compounds of the soil and be involved in the removal of pollution. Due to the extent of their roots in the soil, grasses have the most contact between their roots and pollution, which is very important in removing pollution.
3- Electricity production using refinery waste
The decrease in the quality of crude oil and the increase in the pressure of environmental laws have caused a major tendency to use new technologies, including gasification, to exploit the waste residues of refineries, resulting from crude oil. In this regard, producing clean electricity without polluting the environment is very important. Electricity production in cycles with 40% efficiency with a final cost of $1,365 per kilowatt, at the rate of about 32 kilowatts per barrel of oil waste, creates a great attraction for using the gasification process in line with electricity production. Especially when it results in massive savings ranging from $13,000 to $52,400 per calendar day for refineries.[5]
4- Cement production using petroleum waste
For the first time in the Middle East, a technology unit located in Isfahan’s comprehensive growth center started producing cement using oil-contaminated sludge to solve the environmental problem of oil waste for several years.
Hossein Fakhari, CEO of Isfahan Scientific-Research Town, said: One of the problems in all oil industries, including refineries, petrochemicals, extraction and transportation centers, and terminals, is the problem of waste containing heavy metals and petroleum compounds in different stages of the process, which It has become a serious environmental problem. In fact, these two types of compounds make the disposal of petroleum waste environmentally prohibited and harmful. He stated that the disposal of oil sludge in the environment has been prohibited for many years in the whole world, and added: Due to the fact that waste water leaks into underground water sources and penetrates the roots of plants on the one hand and enters the human food cycle, their disposal in The environment is forbidden and this waste is being produced regularly.
He clarified: Before this, oil sludge was burned and its heavy metals remained because they could not be burned, and this created another pollution, but now the method of using oil sludge in the cement production process is one of the best solutions to solve this problem. Is.
Fakhari stated: This method has been implemented in some industrialized countries such as America and Canada and some European countries, and in addition, by stabilizing heavy metals in the concrete structure, it leads to preventing any environmental consequences. Also, the heat content in petroleum waste is also used as a part of fuel for cement furnaces. He mentioned the use of petroleum waste as input for cement production raw materials and energy saving for cement factories among the advantages of this method and said: Fortunately, waste analysis is very consistent with cement production raw materials and the quality of produced cement is not only changed It didn’t, but it got a little better.
Fakhari reminded: One of the technology units of Isfahan Scientific-Research Town, in cooperation with Sepahan Cement Factory, for the first time in the regional countries, has successfully implemented the use of oil sludge in the cement production process. In this context, as the first industrial implementation, by examining and analyzing the petroleum wastes of the Isfahan refinery, nearly 381 tons of these wastes were transferred from the location of this refinery to the said factory, and by providing a specific formulation and mixing ratio, these wastes were used in the cement production process with used successfully.
The CEO of Isfahan Scientific-Research Town considered the other advantages of using refinery oil sludge in the cement production process to stabilize heavy metals in the concrete structure, without any environmental consequences and saving energy consumption for cement production, and added: improving the mechanical properties of the produced concrete. And solving the environmental problems caused by these sludges is one of the other operational advantages of this plan.
Regarding the concrete blocks produced from these wastes, he said: first, we completely chemically and physically analyzed the oil sludge, then presented the obtained formula to the factory and tested it, and at the end, we produced the concrete blocks that were exposed to water. And the environmental conditions for one to two months did not release any environmental waste materials.
Conclusion:
Accidental, general or operational discharge and disposal of oil by ships, especially oil tankers, oil transfer lines and platforms far from the coast, are one of the major and clear causes of oil pollution in marine environments. Natural processes such as physical, chemical, and biological are the reasons for the release and discharge of oil into marine environments. The release of oil can have wide consequences in the environmental field as well as economic-social fields and cause changes in these levels. Marine and coastal habitats, wildlife species, restoration and restoration activities, local industries, fishing, tourism and water sports are very important centers and sectors that can be affected by the dangerous consequences of oil pollution. On the other hand, they disrupt the food chain by affecting planktons. Sunlight penetration is prevented by covering the water surface with oil materials and layers. It has a direct effect on the amount of primary production as well as the amount of oxygen in the water. Oil pollution causes destruction of beaches, aquaculture and fishing, and this (oil pollution and emission) affects sea birds, marine mammals, fish, snails, sea bottom animals. Due to their immobility, benthic animals such as bivalves are among the creatures that quickly perish as soon as they come into contact with petroleum materials.
Offers:
1) Better understanding and knowledge of the ecology and ecology of coastal areas and assessing the importance of the consequences caused by oil spills and oil accidents.
2) Assessment of environmental consequences before oil exploration and extraction, which are necessary to implement.
3) More findings about environmental research, environmental protection and the preparation of agreement documents, as well as the quality assessment of the communities producing petroleum products.
4) Using optimal time and forecasted meteorological data using maps with optimal scale suitable for coastal areas.
5) Construction of local response and control centers for oil spills along the coastline.
6) Petrochemical industries should be in full cooperation with international and government research centers to reduce the frequency of negative consequences of oil spills.
Rapid cleaning of released materials and oil pollution along with the cooperation of industries and various government agencies.
