CC BY
74
Beneficial utilization of oily wastes,
clean up of geological medium in hungary
as we say in Hungary, when it comes to environmental protection the oil industry is like the «veterinary horse»*, which demonstrates all possible illnesses that can be studied. From this standpoint the oil industry has its significance regarding environmental protection development and the examples and lessons learned that go beyond this industry.
The oil industry is unique because it is the epitome of industrial activities and output of products; has impact on the environmental state of a country, even if that country has no or insignificant oil industry.
Abatement of some of these environmental issues — noise, air pollution, wastewater treatment, sulfur content of products, aromatic content, etc., demand complex solutions, a kind of competition between the emission standards and technologies. However, it can be said that if the problem is managed by the introduction of suitable solution-providing technologies, then the rest is to arrange by nature, which normally (with some exceptions) has the ability to degrade and dilute generated contaminations above threshold limits.
The proper management of wastes, soil and groundwater related problems are the challenge. Where previous environmental damages occurred, the cleanup of the environment is a serious job. If we modify the technology to prevent waste generation we solve only half of the problem, the other half remaining is to deal with the pollution left behind.
In the present study we deal with the problems of the oil industry which resulted in permanent damages to the environment with combustible wastes, therefore with heat value content, including oil contaminated soils-, geological medium and groundwater cleaning experienced in Hungary.
1. Some legal aspects / questions related to environmental protection
Before we get into concrete and typical environmental damages and the Hungarian experience, we need to address some particular questions related to environmental legislation and regulations.
Worldwide, environmental protection is probably the only area where retroactive legislation and laws are adopted, therefore cannot be argued that when we polluted the ground, groundwater and disposed wastes in pits (without technical protection) nothing was forbidding this. At most we can avoid are fines, but not the costs associated with solving the problem. Hungary as member of the European Union (EU) in many respects, took and applied the EU case law - such as the classification of hazardous waste - which differs significantly from the practice other industrialized countries such as the USA. However it may be surprising that with the same laws integrated how much different jurisdictions of one or
* It is like the horse in the collection of a veterinary college, demonstrating all conceivable illnesses.
Dr. ERNO TOROK,
Dr. GYULA GATI
PROCALOR Ltd., Budapest, Hungary
In the present study we deal with the problems of the oil industry which resulted in permanent damages to the environment with combustible wastes, therefore with heat value content, including oil contaminated soils-, geological medium and groundwater cleaning experienced in Hungary.
Keyword: utilization, oily wastes, Hungary, groundwater cleaning, KALOREX.
other countries are, in fact, this issue is not only the country, but may be dependent of governments.
For example, for some time, Hungary did not recognize the beneficial utilization in co incineration plants of wastes from oil industry with a calorific value for energy recovery, despite the fact that the wastes undoubtedly are utilized as a fuel, but regarded it as "disposal". In power and cement plants, where wastes were utilized, the waste incineration legislation had to be applied, the activity had to undergo public hearing, approval by the local governments, authorities etc. The public often prevented the use of waste to be utilized for energy recovery. For these reasons, considerable amounts of oily wastes were exported to other EU member states - especially Germany - where these issues are more flexibly managed.
We tried to avoid this problem by producing a product from the wastes of the oil industry, since the use of these were allowed, and was no need of public hearings, etc. From legal side, this apparently was not a problem either, since typically the waste had to be processed to be suitable for beneficial use in power and cement plants. However, we also ran into problems because the legislation which allowed the option to exclude waste from classification when used as a product of these was missing. So whatever we have done with the waste to make a product still maintained a waste definition, but specifically from a legal view.
The Hungarian legislation regarding waste exports / imports is also different from that of other EU countries. Wastes can be exported but not imported into the country, even if there are no environmental risks associated or the waste is utilized beneficially as a fuel replacement. For example Romania, which allows waste importation from other EU countries, but refuses wastes from Hungary, as a principle of reciprocity.
The 'polluter pays' principle is the basic rule of law which - related to our topic - in essence means that all damages caused have to be paid by the oil industry, even though the contamination is not caused directly by the oil industry, but indirectly is implicated. For example, instances such as intentional damage of pipelines for product theft. Naturally, the oil industry may (try to) pass on costs the environmental cleanup, but firstly they are responsible for damage control and restoration at their own expense.
Another important principle is the waste disposal, which remains the duty and responsibility of the waste generator. The responsibility, cannot be waived by handing it over to someone else claiming they can dispose the waste, even with the required paperwork and ability to perform the work. Indeed, it may turn out that the disposal or handling was not successful and it may happen that this is returned to the generator - in this case the
oil industry - regardless if the cost of treatment that may have been paid. It is not sufficient to that a contractor under license entitling it to take over the waste, but proper treatment should be verified, even at the premises of the contractor, verifying that the disposal or recovery of the waste is completed successfully.
There is another Hungarian legal practice we need to address that is relevant to our topic. If the waste pollutes the ground, the contaminated soil will become «contaminated geological medium», but if the same contaminated soil is excavated, it becomes a hazardous waste, which is covered by different legislation. This has significance from stand point of so-called «in situ» and «ex situ» treatment methods, with which we address later.
2. Utilization of oily wastes with heat value content
Oily wastes with heat value content are generated in all branches of the industry, including the mining, processing and trade areas.
2.1. Utilization of wastes from oil mining
In Hungary, annual oil extraction was historically around 2 million tons, which is decreasing year by year, and currently ~1.5 million tons. From these mining activities thousands of tons of oily sludges were generated. The main sources were the following:
• contaminated soils due to pipeline punctures, faults;
• cleaning of oil wells;
• cleaning of tanks and technology.
Earlier, the oily wastes as described above, were collected and stored in pits and later in concrete basins, which were further contaminated by precipitation
Figure 1. Oily sludge waste storage pit
Figure 2. Concrete storage for oily sludge waste
Figure 3. Stratification of oily sludges in pits
Figure 4. Oily phase and oily water treatment
(snow and rain). Occasionally the floating oil layers were skimmed, cleaned and after filtering was returned
into the refinery. In Figure 1 is presented an older earthen pit and in Figure 2 a later concrete storage for oily sludge.
Because of the earth pits, the oil industry had more conflicts, for example with hunting societies, because the deer and boar population became tainted with oil residues left in the open. Later all kind of debris, municipal waste started to accumulate in the pits and public started to use them as waste dumps. These pits required constant attention; after heavy rainfalls the floating oil had to be removed, monitoring wells were installed and the residues were, sampled and analyzed, etc. Problems occurred with the concrete basins as well; the concrete was not long lasting and cracked. Later, during the liquidation of these old pits, we learned that the oil penetrated in the reinforced concrete as well and the oil contaminated concrete had to be dealt with separately as a hazardous waste.
We also discovered that over time in the storage - in both earth pits and concrete basins - the water somewhat behaved like a fractioning tower of the oil industry, not in terms of its boiling point but rather specific gravity, and formed stratification of the oil fractions. In the bottom of the pit the heavy oil fraction continuously accumulated since skimming removes only the lighter, diluted oil layer. At the various phases there was oil in the water or water in the oil emulsion (Figure 3) levels.
Upon removal, particular attention should be paid to removal methods to properly deal with the respective layering conditions; since improper removal methods will make cause «cross-contamination» and make the handling of the material more difficult. We removed the material from the top into steel tanks, similar to skimming, and the oil was heated, sediments settled and emulsion treated for breakdown with chemicals.
For the treatment of oily water and breakdown of emulsion we mobilized separate technology shown in Figure 4.
The separated oil, if the quality is adjusted (water content and mechanical impurities) can be returned to the oil industry or sold to power or cement plants for fuel.
For the beneficial utilization of the bottom sludges from pits - which could be of high heat value - sticky, heavy oil rich in asphaltenes requires a very different technical solution.
In Hungary this material was utilized in power and cement plants is such way that the sludge was mixed with coal fines to meet the consistency required by user, which consistency could be also modified by sawdust or other additives. This material was named with a fantasy name called KALOREX. The system shown in Figure 5 is a smaller capacity feeding, homogenizing unit, used mainly for modeling and trials, but later proved to be suitable for treatment of materials from smaller storage pits. By adjusting the appropriate rates, is suitable - from 2-4 components - to produce consistent quality fuel for heating purposes.
Figure 6 shows a much larger capacity, KALOREX producing grinding/homogenizing technology system, with continuous feed by conveyors, the capacity being couple of hundred tons per day. Figure 7 shows an overview of the same system.
The next, Figure 8 and 9 shows the end product and material receiving at the power plant.
The processing activities were preceded by systematical lab analysis and tests, and in the power plant air emission measures, numerous full scale slag and fly ash analysis were performed. In the current study, due to space restrictions we are not presenting these results, but in summary we can say that the air emissions and combustion residues of the power plant have been very good.
2.2. Utilization of the oily waste generated from refining
In Hungary, the biggest volume of waste generated from refining activity was acid tar, which was deposited in multiple locations, typically in unlined earth pits. The quality of acid tars from various locations was significantly different regarding acidity, oil and sulfur content. The total volume of acid tars exceeded 100.000 tons.
The acid tars resulted from refining with sulfuric acid and was generated mainly between the two world wars, a smaller volume was generated in the 1990s when the technology was used for making specialty products like medical Vaseline. The freshly generated acid tar is a very aggressive material with up to 70-80 % sulfuric acid content.
The sulfuric acid content of old acid tar decreased over time, even down to 7-8%, but yet is still a very aggressive material and should be handled accordingly. The problem was increased by the fact that in the pits catalysts, waste oils, bleaching earth and laboratory waste was also dumped. Acid tars were also stored in critical locations, e.g., pits 20-30 meters from the Danube River, surprisingly these pits with clay lining helped the formation of spontaneous insulation and did not compromise the water of the Danube.
The other main waste type generated from refining activities was the active carbon residue generated from the production of maleic acid anhydride. This was stored in concrete basins and about 10.000 tons was utilized after pretreatment as an alternative fuel. This waste material is chemical mixture of activated carbon, maleic and fumaric acid, the heat value due to oxygen content of the components is lower, as well as the aggressiveness and was easier to pre-treat.
In the case of maleic acid waste and low acidity old acid tars, the skimming known in the oil mining described before, and the layered removal of the materials is not applicable. These materials were removed after preliminary laboratory experiments and modeling, the pH was adjusted with lime. During neutralization of the acid tars, due to exothermic reaction the material initially was liquid than subsequently solidified, having a rigid, carbon-like consistency.
Figure 5. Pilot plant for dosing/mixing of heavy oil sludges for alternative fuel ((KALOREX) production
Figure 6. Grinder/homogenizer production line for KALOREX alternative fuel
Figure 7. KALOREX alternative fuel production line overview
Figure 8. Alternative fuel (KALOREX) produced from oil sludge for use in power plant
Figure 9. Alternative fuel (KALOREX) delivery at the power plant
Figure 10. Acid tar pretreatment by neutralization and removal by excavation
Figure 11. Excavation of maleic acid still bottom waste
Figure 12. Alternative fuel oil production from acid tar sludge
The material pre-treated, as in the case of oil mining wastes previously described, was by mixing with coal and sawdust, preparing the so called KALOREX plant fuel.
The high sulfuric acid content fresh acid tar utilization fundamentally was different. Since the viscosity of the oil constituting the acid tar was small, this material was utilized as liquid alternative fuel, and because the material was still considered hazardous waste even after the treatment, the use of this was in the heating boiler of the plant which requested environmental permits (Figure 10,11).
The liquid fuel produced was called «alternative fuel oil». The utilization of it was identical as in the case of standard commercial fuel oil.
The first step of the technology after removal of the material by excavation was the neutralization with lime, performed in neutralization and sedimentation basins, than the separation and cleaning of the oil phase. The technology is illustrated in Figure 12.
As result of the above activities the legacy wastes of the oil industry in Hungary was utilized, the environmental risks terminated. The experience gained was further valuable for example in projects in Romania, where legacy waste accumulations were grater then those in Hungary. The Hungarian experts involved in the liquidation of legacy wastes in Hungary participated as advisers, consultants in other cleanups, but in every case the local specifics and problems need to be addressed at each specific site. At present we are in contact with several similar potential projects in South Eastern Europe.
3. Cleanup of contaminated soils and groundwater
After the liquidation of waste pits, the oil industry continues to face the additional problems of contaminated soil and associated possible groundwater pollution remediation.
Remediation of polluted soil and groundwater generated a broad range of publications and literature in the subject broadly available on the Internet for those who are interested, therefore we are not intending to describe these references, but rather focus solely on our experience in Hungary.
The problem of soil and groundwater pollution does not occur only in the case of oily waste storage, but in fact can arise related to almost all activities of the oil industry due to technical breakdowns, intentional vandalism, or human error.
Because of this, in Hungarythe oil industryis obligated by law to investigate the environmental condition of its sites. In addition, investigation is mandatory when a site, oil well or collection station is finally suspended or closed, and activities are abandoned. In all cases when soil or groundwater contaminations due to pipe leakage, emergency spills occur environmental investigation must be carried out.
3.1. Sources of soil and groundwater pollution in the oil industry, environmental investigations
Hungary is a small country compared to the size of the Commonwealth of Independent States countries or their oil industry, but still this small country has tens of thousands of kilometers of pipelines capable for leakage and great environmental damage to its resources and people.
Protecting the environment was a challenge for the Hungarian oil industry and still is; the intentional perforation of fuel pipelines for the purpose of theft of products is a real situation. Though the installation of detecting sensors these thefts on pipeline systems have decreased, however thefts of light distillates and volatile naphtha fraction pipes continues by tapping through criminal activities.
In some instances, the pipeline sensors did function properly and there were many false alarms due to the cavitation in the pipes. Consequently, a whole new industry was established by tapping into product pipelines, especially those in the southern Hungarian Plains region. Criminal elements established homesteads near pipelines who stored stolen oil products in their yards. At all theft locations significant environmental pollution, soil and groundwater was experienced.
The following figures show locations and examples of various pollution sources which caused soil and groundwater contamination, beside the previously discussed earth and concrete waste storage pits shown in Figures 1 and 2.
We note that are only a few instances -due to unique geological conditions like clay soils and very low groundwater table - that soil contamination did not result in groundwater pollution as well. These are rather few exceptions since in most cases the soil pollution traveled to the groundwater (Figure 13-17).
In all damaged sites the first action is perform a survey, or an environmental site investigation. For environmental surveying and risk assessment - as in all developed countries - Hungary maintains standards which must be respected to assure accountability required by environmental authorities. The survey starts with soil and groundwater sampling analysis of
Figure 14. Oil collection station
Figure 15. Deliberately perforated oil pipe with purpose of stealing petroleum products (With the theft structure shown in the figure)
Figure 16. Oil pipe perforation due to corrosion
Figure 13. Oil well and environment
Figure 17. Old oil collection station buried with soil
Figure 18. Soil and groundwater sampling
[mg/kg] 5000 3000 300 100
Figure 19. Typical soil contamination map (for total paraffin hydrocarbons - TPH)
the samples by accredited laboratory (Figure 18).
The results of the investigation are illustrated on pollution migration maps, in general and typically separately for each variety of contaminants. The level and extent of the pollution is marked with different colors in the color spectrum. The results are evaluated within a risk analysis framework to determine the human threat of the pollution, and determine the likelihood of cancer within 5-30 years in the area's population (Figure 19-21).
Similar illustrations are separately made for other contaminants, such as aromatics, PAH and heavy metals. In the investigation report recommendations for proper cleanup must also be made. The documentation must be submitted to environmental authorities who may request supplemental investigation or approve the recommended investigative works and make provisions for further actions. An action plan is usually prepared for intervention at the polluted location with the approved clean up method or technology chosen for remediation.
3.2. Experiences related to cleanup technologies applied in Hungary for soil and groundwater remediation
The remediation of soil and groundwater are closely related. The most important experience is that the cleanup of the groundwater is effective only if the source of contamination is removed from the soil; respectively the free phase contaminant floating on the surface of the groundwater was also fully removed.
The free phase floating on the surface of the groundwater can be removed effectively and quickly with the safe excavation of soil - with this activity the contaminant trapped in the soil structure is removed - but in the case of groundwater with 6-8 meters below ground level this is not an ideal solution. In such cases the removal of contaminant floating on the surface of the groundwater should be started with
Figure 20. Floating free phase on groundwater in one of the contaminated sites
Figure 21. The location of TPH (total paraffin hydrocarbon) contamination in groundwater at one of the investigated polluted site
targeted technologies. Figures 22 and 23 illustrate a flow diagram, skimming equipment, and technologies that may vary primary in the removal technique, mechanism of wells and probes.
The technology design must consider the soil structure, and transport process of the fluid phases.
The works must be continued until the contaminant phase does not separate from groundwater. The groundwater level change and fluctuation must also be taken into account, since it frequently occurs that at the higher groundwater table level the contaminant does not separate, however, if the level decreases the free phase may appear again.
In case that the free phase formation discontinues, based on experience the dissolved hydrocarbons in the groundwater due to the effect of natural hydrocarbon degrading bacteria in 1-2 years spontaneously greatly reduces or eliminates the contaminant and the groundwater is clean. This natural course can be accelerated or facilitated by adding hydrocarbon degrading bacteria and maintaining the living conditions of these organisms. We successfully applied technological varieties when the dissolved hydrocarbon from groundwater - after extraction -was treated by stripping or reduced with active carbon sorption below threshold limits.
In the groundwater treatment field, the Hungarian oil industry pursued its own proprietary developments as well; substantial success was archived regarding the use of in situ sorption probes installed in groundwater wells with computer controlled systems which moved the contaminants vertically.
For soil treatment in Hungary, basically two methods were applied; one treated soil with bioremediation, and the other by thermal desorption. Bioremediation has two versions, ex situ and in situ methods, namely the excavation or by treating the contaminated soil in place.
The biological treatment of soil generally is generally considered a more inexpensive solution, however our experience showed that successful biological treatment is not cheap. It is very important that the excavated soil is screened, homogenized with nutrients, higher oil lumps are grinded, mixed, and prisms are created, which are then injected with inoculation made of bacterial strains selected through laboratory tests. In addition, from time to time, the prisms must be turned over, and if needed re-inoculated to replace nutrients. In addition, the conditions of the prisms should be sampled repeatedly and checked by the laboratory for progress at least on a quarterly basis.
The experience is that the bacteria may be "selective", they quickly digest aliphatic hydrocarbons, and less likely the heavier aromatics, and not at all, the polyaromatics. Thus, it is possible that the total hydrocarbon content reduction appears favorable, since the hydrocarbon content of
Figure 22. Free phase contaminant removal from polluted geological medium
Figure 23. Free phase removal with skimming technology
Figure 24. Soil contamination treatment by bioremediation at one of the polluted locations
CONTAMINATED SOIL STOCKPILES
^aSOIL FEED jBr SYSTEM
ЕД CLAY SHREDDER
Figure 25. Flow diagram of a thermal desorber
Figure 26. Thermal desorber
soil is effectively reduced, and sets to a low level. However, from an environmental aspect the most critical aromatic and polyaromatic hydrocarbons, are left far above the threshold limits set for these hydrocarbons.
Biological treatment activities in Hungary, was carried out by private enterprises working for the oil industry and is still done today. Unfortunately, especially in the early days of environmental protection activities, that the oily soils were not properly handled, large quantities of oily soils were accumulated, treatment fees accepted by contractors and the respective enterprises declared bankruptcy leaving the contamination remaining. In these cases, the oil industry had to resolve the problem, with the treatment cost for soil cleaning paid again until the soil contamination
was resolved. In Hungary, the disposal or recycling of the waste is the obligation of the producer and this responsibility lasts until this task is achieved, indifferent if the waste is on the premises of the oil industry or the contracted enterprise site (Figure 24).
As discussed above and our experience the biological treatment process is not cheap and there are significant risks to success. However, the advantage can be in case of smaller volumes, and can be carried out handling approximately 100-200 tons of material on site.
There are times when ex-situ process, namely soil removed by excavation methods cannot be used. Such cases are for example when the hotspot of the pollution is under a building, tanks and/or industrial installations. In these cases in-situ biological treatment is the only possible solution for remediation.
Reviewing international experience it can be stated that many European countries (e.g. Germany, Netherlands) primarily used biological treatment, however in the United States, biological treatment of soils in recent years was significantly decreased, hardly reaching 10%. In these countries, the new technology for treatment of oil contaminated soils is the thermal desorber.
The thermal desorber is a rotating cylindrical kiln, which is heated with a direct flame. Once the tainted soil is fed into the cylinder, and it has the proper moisture content, the water is vaporized around 100 ° C and the gaseous phase separates by stripping the oil from soil particles, which is travels as a gas and incinerated in a secondary oxidizer. It is important to clarify that the soil is not incinerated; to preserve the organic matter of the soil. Thus, the stripped soil is clean; and the nutrient content is not totally lost.
The thermal desorber is available in many varieties; small portable equipment are suitable for mobility and changing locations, the larger ones are suitable for permanent sites operating as fixed treatment plants. The smaller units have higher per unit costs than the larger unit ones.
The flow diagram of the thermal desorber is shown in Figure 25, the photo in Figure 26.
The disadvantage of this method is that needs at least 10,000 tons of soil to be treatment in one location, in which case is advisable to mobilize technology near the contaminated site, in other cases it is to ship the contaminated soil to the unit.
The experience with this process was very positive.
ПОЛЕЗНОЕ ИСПОЛЬЗОВАНИЕ НЕФТЕСОДЕРЖАЩИХ ОТХОДОВ ПРИ ОЧИСТКЕ ОКРУЖАЮЩЕЙ СРЕДЫ В ВЕНГРИИ
ЭРНО ТЁРРЁК, ГЮЛА ГАТИ
PROCALOR LTD. Будапешт, Венгрия
АННОТАЦИЯ
Нефтяная отрасль оказывает сильное влияние на экологическое состояние страны, даже если страна имеет незначительные объёмы нефтедобычи и нефтепереработки. В Венгрии годовая добыча нефти в настоящее время составляет около 1,5 млн т. Актуальными задачами являются: снижение шума, загрязнения воздуха, снижение содержания в продукции серы, ароматических углеводородов и др. Растёт спрос на комплексные решения. При этом необходима серьезная работа по очистке окружающей среды там, где уже нанесён экологический ущерб.
В настоящем исследовании представлен опыт специалистов Венгрии по решению проблем полезного использования отходов нефтяной отрасли, которая нанесла ущерб окружающей среде и привела к образованию горючих отходов, в том числе загрязнению нефтью почв, геологической среды и подземных вод. Рассмотрены некоторые правовые аспекты, связанные с охраной окружающей среды. Например, в Венгрии долгое время не признавали выгодное использование процесса сжигания отходов нефтяной промышленности с высокой теплотворностью для выработки энергии и в качестве топлива, а расценивали это как «удаление» отходов.
В статье приведён ряд мероприятий, направленных на борьбу с нефтяными загрязнениями, осуществленных венгерскими специалистами.
1. Утилизация нефтесодержащих отходов с теплотворными свойствами. Рассматривается использование нефтесодержащих отходов, находящихся на хранение в ямах и бетонных бассейнах, которые в дальнейшем были загрязнены осадками (снегом и дождем). Представлена технология, которая была использована для разрушения водно-нефтяной эмульсии. Для выгодного использования осадка со дна ямы, который обладает высокой теплотой сгорания (липкие, тяжелые нефтяные остатки, богатые асфаль-тенами) требуются очень разные технические решения. Венгерскими учеными продукты из такого осадка были использованы на цементных заводах для смешивания с угольной мелочью или, в зависимости от дальнейшего использования, опилками или другими добавками. Полученный материал был назван KALOREX и предназначен для отопительных целей. Отработана технология получения аналогичного продукта для электростанции. После многочисленных испытаний установлено, что выбросы в атмосферу при сжигании продукта на электростанции экологически чистые.
2. Утилизация нефтесодержащих отходов, образующихся в результате нефтепереработки. В Венгрии самый большой объем таких отходов составляют кислые гудроны, которые хранятся в ямах, как правило, без подкладки на земле. Качество кислого гудрона в различных местах существенно отличается по кислотности, содержанию масла и серы. Общий объём кислого гудрона превысил 100 тыс.т. Кислый гудрон хранился также в критических местах, например, в ямах в 20-30 м от реки Дунай. Другой вид отходов, получаемый за счёт производства малеиновой кислоты, был использован после предварительной обработки в качестве альтернативного топлива взамен мазута.
3. Очистка загрязненных почв и подземных вод. Представлен опыт венгерских специалистов по решению проблем загрязнения грунта и грунтовых вод, которые могут возникнуть в связи, как с техническими поломками, так и намеренного вандализма, или человеческой ошибки.
Венгрия имеет десятки тысяч километров трубопроводов, где возможно создание утечек. По каждому случаю ведётся расследование, создаются миграционные карты, в целом, и, как правило, отдельно для каждого вида загрязняющих веществ. В отчете о расследовании должны быть даны рекомендации правильной ремедиации почв и грунтовых вод.
Для обработки почвы в Венгрии были применены по сути два метода обработки почвы: биоремедиация и тепловая десорбция.
Биоремедиация имеет две версии, ex-situ и in-situ методов, а именно, обработки вынутого грунта или на месте. Очень важно, чтобы вынутый грунт был проверен, гомогенизированы питательные вещества, затем сделаны прививки бактериальных штаммов, выбранных с помощью лабораторных тестов. Время от времени, нужно заменять питательные вещества. Общее содержание углеводородов вследствие их «поедания» бактериями в почве сокращается и устанавливается на низком уровне. Однако содержание наиболее экологически опасных ароматических и полиароматических углеводородов остаются намного выше порога лимита, установленного для этих углеводородов.
Бывают случаи, когда процесс ex-situ, а именно процесс выемки грунта, не может быть использован. Например, когда очаг загрязнения находится под зданием, нефтехранилищем и/или промышленными установками. В этих случаях биремедиация in-situ является единственно возможным решением.
Во многих европейских странах (напр. Германия, Нидерланды) в основном используется биологическая очистка, однако в Соединенных Штатах, биологическая обработка почвы последние годы почти не используется. Для очистки нефтезагрязненных почв используется новая технология — тепловая десорбция. В статье подробно представлена эта технология. Был получен положительный опыт использования этого процесса.
В результате вышеуказанных мероприятий скопившиеся отходы нефтяной промышленности в Венгрии были рационально использованы, экологические риски прекращены. В каждом случае необходимо было учитывать местные особенности, и проблемы должны были решаться на каждом конкретном участке.
Ключевые слова: Венгрия, нефтяные отходы, утилизация.
