Oil Shale Industry Research Articles

Survival of black alder ( Alnus glutinosa L.), silver birch ( Betula pendula Roth.) and Scots pine ( Pinus sylvestris L.) seedlings in a reclaimed oil shale mining area

Early survival and growth of black alder, silver birch and Scots pine were investigated on reclaimed extremely stony and heterogeneous calcareous (pH 8) opencast oil shale mining areas (OOSMAs). Biomass allocation, production, leaf and root adaptations, and mineral nutrition in relation to tree species and soil heterogeneity were analysed. The adaptive strategies of tree species in first-year plantations on OOSMA were different. Scots pine allocated 1.5–2 times more biomass into leaves and fine roots than deciduous trees. The lower leaf/fine root biomass ratio was in proportion to the better survival (%) of seedlings, decreasing in the following order: black alder (93%) ≥ Scots pine (83%) > silver birch (64%). Deciduous trees improved mineral nutrition more by fine-root morphological adaptations than Scots pine; e.g. the mean specific root length (SRL, m g −1) of short roots increased in the following order: Scots pine (62) < black alder (172) < silver birch (314). The effect of soil heterogeneity on growth and adaptations was minor. All studied species suffered from P and N, and deciduous species also from K deficiency. In the first year after planting, black alder was best adapted to the harsh conditions of the post-mining substrate. The approaches of this study can be used for other regions where wastelands require reclamation.

Conceptions about Establishment of the Environmentally Harmless Oil Shale Mining and Chemical Complex

Estonian oil shale deposits have the age-old experience of mining and thermal processing of this hydrocarbon mineral, which is unique in its natural and chemical properties. Oil shale mining perspectives and experience of its burning and thermal processing accumulated by mining, power, and chemical industries of Estonia are very important factors of the economic development of the country on a whole. Authors have studied new methods of oil shale mining and its industrial use in the U.S., Australia, Russia, and Sweden. Production achievements of oil shale industries of Estonia have been analyzed as well. “Estonia” mine, with perspective reserves of this mineral as well as experience of exploitation of natural resources in mining operation areas, was taken as the basis for approval of the idea of complex use of oil shale and underground gotten mines. Technical and organizational development for establishment of environmentally safe and economically sound multi-product mining and chemical complexes at the Estonian oil shale deposits are given in the article.

Carbon sequestration in a chronosequence of Scots pine stands in a reclaimed opencast oil shale mine

Ecosystems that develop on mine spoil can serve as significant sinks for CO2. The aim of this study was to estimate the rate of carbon accumulation and its distribution along forest ecosystem partitions in young Scots pine ( Pinus sylvestris L.) plantations in the Narva oil shale opencast, Estonia. The tree layer was measured in 2004 in 13 stands afforested with 2-year-old seedlings during 1968 to 1994. Three stands (afforested in 1990, 1983, and 1968) were selected for detailed analysis of the carbon sequestration. Soil profiles were sampled in these stands in 2005. Radiocarbon analysis combined with a simple model of litter production was used to differentiate between plant-derived recent carbon and carbon stemming from fragments of oil shale. Total carbon accumulated since afforestation in vegetation, forest floor, and A horizon was 7.8 t·ha–1in the stand established in 1990, 34.5 t·ha–1in that established in 1983, and 133.4 t·ha–1in that established in 1968. Most of the sequestered carbon was allocated to tree stems; their portion increasing with age from 28% to 51%. The portion of recent soil organic carbon increased from 5% to 23%, which shows that soils contribute significantly to carbon accumulation during early forest succession on degraded land.

IMPACT OF OIL SHALE MINE WATER ON HYDROLOGY AND RUNOFF OF A SMALL RIVER. THE PÜHAJÕGI RIVER CASE STUDY

The Puhajogi River runoff components (infiltration, interflow, groundwater recharge) and human impact (discharge of mine water and municipal wastewater) have been studied during three periods (1945–1963; 1978–1990; 2000–2003). This study characterises different hydrological periods: natural state of the river, influence of intensive mining and closing down of mines. The basic balance schemes based on available data have been worked out by linear regression calculations. The collected data is annual and gives a general overview. The study shows that mine water exerts a significant impact on the river runoff and also confirms that human impact has considerably changed the average runoff of the Puhajogi River after the 1960’s. It was established that the average runoff from the river catchment area enlarged by almost 24%, compared with the average natural surface runoff. During the period when oil shale mines were being closed, the average surface runoff of the Puhajogi River decreased by more than 38% compared to that of the oil shale mining period. However, the annual amount of precipitation has continued to increase within all observed periods.

NOVEL APPROACHES TO BIOINDICATION OF HEAVY METALS IN SOILS CONTAMINATED BY OIL SHALE WASTES

The major sources of heavy metal pollution in Estonia are oil shale industry and oil shale combustion. There is an utmost need to monitorsoil pollution with heavy metals in this region. Earthworms are good accumulators of heavy metals and can be used as bioindicators. Endogeic species Aporrectodea caliginosa and Aporrectodea rosea as well as anecic species Lumbricus terrestris are good bioindicators for Zn(II) and Cu(II) ions in soils contaminated by oil waste or fly ash because of the high level of accumulation of these metals in their tissues. Electrochemical methods were used for the determination of heavy metal ions in earthworms as the amount of the sample needed for the analytical work is from 10 to 100 times smaller, when compared to the traditional methods.

Environmental problems in the Estonian oil shale industry

In Estonia technologies for oil shale mining and consuming have been continuously developed for more than 80 years. By March 2006 one billion tonnes of oil shale had been produced in Estonia. Since the 1960s, Estonia has been the largest oil shale producer and consumer in the world. In the 1980s about two-thirds of the world's oil shale output came from Estonia. Serious problems in the mining complex are connected with large losses of oil shale at mining and enrichment (more than 30%) and voluminous dewatering (25 m3 per tonne of oil shale). After mining and beneficiation, much limestone remains unused and is deposited in waste dumps. Oil shale waste and waste heaps may be considered a rather innocent production residue; however, from time to time they are subject to self-ignition. Following combustion of enriched oil shale, ash remains which also has to be deposited. The most toxic waste (semicoke) comes from the oil-shale chemical industry. Power stations using oil shale emit large amounts of carbon dioxide and other gases; the groundwater regime, and often also the water quality, are altered in mined-out areas. Environmental effects and the resulting immediate hazards were greatest in the 1980s, now the situation is improving.

Hydrogeologic impacts in the Estonian oil shale deposit

The article describes the hydrogeological problems related to water influx to the mine and water sulphate content association with underground oil shale mining in an environmentally sensitive area of Estonia. The water balance method was used to calculate the ratio of mine water outflow/inflow. Water balance calculations are needed for estimating the groundwater transversal flow into closed mines. Before oil shale mining groundwater geochemical processes are characterised by low sulphate content. Dewatering of oil shale mines lowered groundwater level in the Keila–Kukruse aquifer, and caused an about 50-fold increase in sulphate by intensive oxidation of pyrite of natural origin. The mobile sulphate ion may serve as an indicator of changes occurring in the sulphate content of groundwater stored in the Keila–Kukruse and Lasnamäe–Kunda aquifers of the Ordovician system in the area of closed and working mines. Using the method of inverse mixing, sulphate ion distribution is a possibility to study the movement of groundwater in lateral and transversal directions.

Carbonate precipitation in an ancient oil shale mine (SE Pyrenees): Evolution of fluid chemistry and its relationship with oil expulsion

Carbonate precipitation in an ancient oil shale mine (SE Pyrenees): Evolution of fluid chemistry and its relationship with oil expulsion

Mycorrhizal interactions of orchids colonizing Estonian mine tailings hills

Northeastern Estonia is home to extensive oil shale mines. Associated with these are desolate and environmentally damaging hills of ash and semicoke tailings. Interestingly, some of the first plants to colonize these hills are rare orchids. Here, we assess the identities of the mycorrhizal fungi associated with these orchids, in particular Epipactis atrorubens, Orchis militaris, and Dactylorhiza baltica, and compare them with mycorrhizal fungi from orchids from pristine habitat. Epipactis atrorubens associated with the widest breadth of fungi, including unnamed members of the basidiomycete family Tulasnellaceae and the potentially ectomycorrhizal ascomycetes Trichophaea woolhopeia and Geopora cooperi. Orchis militaris also associated with unnamed members of the Tulasnellaceae. Dactylorhiza baltica associated with Ceratobasidium albasitensis. In Epipactis and Orchis, the same fungi associated with plants in the pristine habitat as with those on ash hills. The tulasnelloid and ceratobasidioid fungi mycorrhizal with these orchids appear closely related to common orchid mycorrhizal fungi, while one of the ascomycetes mycorrhizal with E. atrorubens is closely related to a mycorrhizal fungus with E. microphylla. Our results suggest that these orchids and their fungi are not limited to pristine habitats and that environmentally polluted sites may present novel habitats that may be exploited for endangered plant conservation.

FUTURE OF OIL SHALE MINING TECHNOLOGY IN ESTONIA

In the future, oil shale mining conditions will worsen and environmental taxes will be increased. Higher calorific value and more homogeneous material are required for more effective usage of boilers and generator units in power stations and oil plants. The solution for the mining industry is related to the optimal usage of mineral and technological resources, utilizing the best available techniques and modelling and visualization of mining impacts for explaining the changes in technology to the influenced parties. The main challenges for technologies in the future are related to the mining in environmentally or socially sensitive areas. One of the solutions could be utilizing selective mining and backfilling. Related tests have shown good results and show a promising future for sustainable oil shale mining.

PSEUDOMONAS PUTIDA P67.2 AND PSEUDOMONAS FLOURESCENS P75 BASED MICROBIAL SENSORS FOR BIOCHEMICAL OXYGEN DEMAND (BOD) MEASUREMENTS IN PHENOLIC WASTEWATERS OF OIL SHALE INDUSTRY

This study evaluates applicability of microbial sensors based on Pseudomonas putida P67.2 (Ps. p.) and Pseudomonas fluorescens P75 (Ps. fl) for BOD measurements in the phenol-containing wastewaters that mimic the wastewaters from oil shale industry. Sensors are calibrated with OECD synthetic wastewater. Linear range in calibration solution for Ps. p. and Ps. fl. sensors is BOD 0-50 mg/L and 0-65 mg/L, respectively. The steady state response time for both sensors is 15-45 min. Measurements show that although Ps. fl. has better sensitivity to calibration solution, the concurrence between sensor-BOD and BOD7 in phenol-spiked wastewater is better for Ps. p. sensor. In linear range the error is only 1.2–13%. For Ps. fl. the error in linear range is 17–55%. Preconditioning in phenol solution (BOD = 5 mg/L) increases sensor’s sensitivity to phenol considerably (52%). This study demonstrates that preconditioned microbial sensors with specifically selected cultures can give better results for fast BOD determination in specific wastewaters.

GEOLOGICAL ASPECTS OF RISK MANAGEMENT IN OIL SHALE MINING

The paper deals with risk management problems in Estonian oil shale mines. Investigations are focused on application of the method to determination of the quality of geological data. Various factors relevant to mining technology in Estonian oil shale deposit have been determined. For risk estimation, the empirical and judgmental approaches and the event tree were used. They allow determining the probability of the occurrence of geological features and its influence on the mining process. Analysis of obtained results showed that it is necessary to elaborate special methods for determination of the geological conditions in the mining area. The obtained information affords specialists to improve the quality of geological information and consequently the mine work efficiency. The analysis shows that the used method is applicable in conditions of Estonian oil shale industry. The results of the investigation are of particular interest for practical purposes.

Aerobic Bio-oxidation with Ozonation for Recalcitrant Wastewater Treatment

AbstractThe aim of the present research was to find a combination of biological and chemical oxidation processes that improves the purification efficiency of recalcitrant wastewater treatment at reduced ozone consumption. The following wastewater treatment processes were experimentally studied: conventional aerobic biooxidation, post-ozonation of biologically treated wastewater, a combined process - aerobic bio-oxidation with ozonation in a re-circulation system - and aerobic bio-oxidation with direct introduction of ozone-containing water into a bioreactor. A synthetic landfill leachate corresponding in its composition to leachate of young landfills, thermo-mechanical pulping water, and phenolic effluent from the Estonian oil shale industry were used as wastewaters. It was established that compared with conventional aerobic bio-oxidation, the combined process enables an improvement in purification efficiency even at relatively low ozone doses (10 to 60 mgO

THE SURFACE MINER SUSTAINABLE TECHNOLOGY INTRODUCTION FOR OIL-SHALE MINING IN ESTONIA

The paper introduces a high-selective oil-shale mining technology and the first results of surface miner Wirtgen 2500SM tests. The technology allows to decrease oil-shale loses from 10-15% up to 5-7%. Mining process of the surface miner has a lower disturbing impact, which is topical in open pits and quarries especially in densely populated areas. The low level of dust and noise emissions and also very’ low vibration are arguments to mine oil shale with surface miner instead of drilling-blasting operations. The risk analysis for testing technology was elaborated.

Environmental problems of oil shale processing industry

Main environmental problems of the full oil shale processing cycle including mining, heat treatment, and direct combustion of oil shale in power plants are considered. Possible lines of utilization of both the mineral matter remaining after shale preparation and ash residues after shale processing are elucidated.

The Use of Bioassays for the Risk Assessment of Toxic Leachates: An Experimental Study

Solid wastes from the oil-shale industry produce leachates containing toxic compounds such as heavy metals and persistent polycyclic aromatic hydrocarbons (PAH). The hazard to the environment represented by waste leachates depends not only on their chemical composition, but also on the mobility and bioavailability of toxic contaminants in soils. We evaluated the applicability of bioassays for toxicity assessment of the bioavailable fraction of heavy metals and PAH in soils, in experiments with samples of four different soil types (Rendzina, Brown pseudopodzolic, Typical brown, Sodpodzolic), the pH of which ranged from 6.2 to 7.2. The toxicity of the bioavailable fraction of the soil contaminants was assessed with the dehydrogenase enzyme activity assay, and with a Toxkit microbiotest with the crustacean, Thamnocephalus platyurus, after treatment of the soil samples with an artificial solution containing chromium (III), lead (II), copper (II), cadmium (II) and pyrene. The test results confirm those of earlier experiments, which characterised the sorption potential of investigated soils for the same compounds. Both tests turned out to be sufficiently sensitive, and hence can be recommended as effective and useful tools for the assessment of the bioavailable fraction of soil contaminants.

Die Arbeiter des estnischen Ölschieferbeckens – eine Industrieregion des Stalinismus

The article deals with the Estonian oil shale region Ida-Virumaa and how it turned into a Stalinist industrial area. Oil shale mining started already in 1916, mining and processing of oil shale expanded largely during the period of Estonian independence due to state protection and subsidies. After the Soviet occupation and annexation of the country in 1940, plans to extend mining and processing developed, but were not fulfilled because of the outbreak of war. Under German occupation the oil shale industry was at first neglected, but beginning with 1943 work intensified with the help of slave labor of Soviet POW‘s and Jewish concentration camp inmates. Soviet reconstruction projected a steep increase of mining and processing. Ida-Virumaa became one major target of industrial investment in the post-war decade, a large “building site of Socialism”. The aims were the provision of energy and the support of Soviet armaments, because uranium could be found in the area and oil and special fuels were desperately needed by the Soviet forces. Like under Nazi occupation, slave labor of POW‘s and camp inmates played an important role until 1949. Because war damages had been the largest in the entire Estonian SSR and living and working conditions were the worst in the republic, there existed an extreme shortage of workers. Campaigns to mobilize Estonians to work there utterly failed. The only way to solve the problem was to hire migrants from other regions of the Soviet Union, where conditions were even worse. The migration led to the Russification of the region, but this development was not intended by the regime. Only in the second half of the 1950s life turned normal and the conditions became bearable.

Ecological efficiency of the oil shale electricity sector of Estonia

Estonia is a typical postsocialist country with an inefficient energy sector, albeit uniquely based on oil shale mining and burning. This article comprehensively analyses the efficiency of the oil shale energy industry from mining to end use. The overall efficiency of oil shale energetics was estimated to be less than 20% (17% in 2002), with the losses attributed to wasting of co-produced thermal energy, coupled with substantial inefficiencies in the mining of oil shale. The Estonian oil shale energy sector is an example of an old-fashioned linear throughput industrial system developed in direct contradiction with the principles of cleaner production. The huge environmental impact of the oil shale industry is compounded by the low energy density and geological characteristics of the deposit, the chemical composition of kukersite and the cumulative nature of environmental destruction.

Changes in lake-sediment structure and composition caused by human impact: repeated studies of Lake Martiska, Estonia

This research uses a comparison of the sediment record of Lake Martiska (NE Estonia) with well-documented historical changes in human impact to identify the factors dominantly affecting the sediment lithological composition, and the accumulation of heavy metals and other microelements into the sediments. To this end, comprehensive lithological-geochemical studies of the upper sediment were undertaken in 1986 and repeated in 2003 and 2005. Oil shale mining and processing heavily impacted the area via atmospheric pollution and groundwater extraction. As a result of the fly-ash deposition clear marker horizons of chemical compounds were formed. Historical water-level fluctuations are clearly reflected in the lithological composition and grain-size variations of the studied sediment cores. During regression and transgression phases displacement of the erosion-transport-accumulation limits caused redistribution of previously accumulated sediments and their return into the biogeochemical matter cycling of the lake. The210Pb chronology of the sediment records is in contradiction with the historical records of fly-ash emissions, suggesting that changes in 210Pb flux and focusing of sediments caused by lake-level change have invalidated the dating models.

APPLICATION OF THE RISK ASSESSMENT METHODS OF RAILWAY TRANSPORT IN ESTONIAN OIL SHALE INDUSTRY

The paper deals with risk analysis/assessment problems in Estonian oil shale industry. Investigations are focused on application of these methods for railway transport from mine to consumer. Various factors relevant to oil shale transport have been determined. For risk estimation an empirical approach, the event/fault tree is used. It allows to determine probability of deviations of the process duration from the mean value for different pathways. The obtained information affords specialists to improve the quality of the railway transport. The analysis shows that the used method is applicable in conditions of Estonian railway systems. The results of the investigation are of particular interest for practical purposes.