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Remediation of Baghalchur's Uranium Dump in Pakistan by using Bacteria
Group No: 2 Imran Abbas Minhas Muhammad Rashid Herkko Jokela Caroline Liu Jason
Högskolan Kristianstad Master in Sustainable Water Management
Table of Contents
1. Background Situation 2. Introduction to Uranium 3. Uses of Uranium 4. Hazards of Uranium 4.1 Uranium Analysis 4.2 How uranium wastes are different from other wastes types? 4.3 Methods to Remediate the Situation? 4.4 Is it True that Bacteria use Uranium as Food? 4.5 Remediation of a situation by bacteria? 4.6 Factors affecting uptake of uranium? 4.7 List of bacteria which can be used to remedify the situation? 5. Name of bacteria which we used to remediate the situation? 5.1 Picture of the bacterium 5.2 Details about the Bacterium? 5.3 How this bacterium utilizes the uranium? 5.4 Application of this bacterium to the polluted site or remediation in the reactor? 6. Discussion 7. Results 8. Conclusion 9. References
1. Background situation
Baghalchur is a small town in the District Dera Ghazi Khan in province of Punjab about 400 km north of Karachi Pakistan. Baghalchur is a place of Uranium mines now being used as a nuclear dump. This place remained 22 years under Pakistan Atomic Energy Commission PAEC for uranium extraction. On the 28th of April 2006 BBC had broadcasted a documentary presented by Nadeem Saeed on “Baghalchur's uranium mines are now being used as a dump”. Residents of the village told that they are facing a severe problem due to the nuclear wastes dumped in their area and they are being slow poisoned. The area has been categorized by the Asian Development Bank as among the most backward parts of Pakistan. One of the residents told that "Our land played an important role in making Pakistan a nuclear power but all we have got in return is poverty and poison. Local people said that there are heaps of yellow cakes scattered openly here and there. In the beginning we were not aware of the condition but now we have to face many problems like animals are dieing, there is increase in the infant mortality rate, and even animals are born with the malformed legs. Not only animals and humans are being affected but also plants. Different people told that yellow cakes are washed by rain water and this water goes to ecosystem through different phenomena like percolation, evaporation and directly to water channels, rivers and canals. Therefore it is posing different threats to bio zones in the vicinity of nuclear wastes heaps.
2. Introduction to uranium Uranium is a white/black radioactive metallic element which is 18.7 times denser than water. Naturally it is found in rocks, soil, and ocean. The symbol of uranium is U and has atomic number 92. It has the highest atomic weight in naturally occurring elements. Uranium was discoverd in 1789 by Martin Heinrich Klaproth.
Uranium was named after the planet Uranus, although the metal is not very common in the solar system. It does, however, provide the main source of heat inside the earth. Uranium is mined for many different purposes and has been used to produce energy for more than forty years. In nature, uranium atoms exist as Uranium-238 and U-235. In 1934 Enrico Fermi started the use of uranium as a as a fuel in the nuclear power industry.
Atomic Number: 92 Atomic Symbol: U Atomic Weight: 238.029 Electron Configuration: 2-8-18-32-21-9-2 Shells: 2,8,18,32,21,9,2 Filling Orbital: 5f3 Melting Point: 1132oC Boiling Point: 3818oC Description: Silvery-white radioactive metal. </TD< tr> Reference: http://www.corrosionsource.com/handbook/periodic/92.htm
3. Uses of Uranium Uranium is used for many purposes. For many centuries it was used as a pigment for glass. Now it is used as a fuel in nuclear reactors and in bombs From lost 50 years it has been used for making of nuclear Weapons and to generate electrical power. By using uranium it is possible to make a wide range of radioactive materials (radioisotopes) at low cost. These radioisotopes are used in medical industry for research and treatment of some illnesses, such as cancer. More powerful gamma sources are used to sterilize syringes, bandages and other medical equipment. Radioisotopes are also used for food preservation. Radioisotopes are used to prevent the produce of leaves of root crops after harvesting. It is also used for killing parasites and pests, and to control the ripening of stored fruit and vegetables. After treating food and vegetable like potatoes, onions, dried and fresh fruits, grain and grain products, poultry and some fish is accepted by world and national health authorities for human consumption in an increasing number of countries. Radioisotopes play an important role for growing of crop and breeding of livestock. They are used to produce high yielding, disease-resistant and weather-resistant varieties of crops, to study how fertilizers and insecticides work, and to improve the productivity and health of domestic animals. In mining industry it is used for examining welds, to detect leaks, to study the rate of wear of metals, and for on-stream analysis of a wide range of minerals and fuels. There are many other uses like detecting and analyzing pollutants in the environment, to study the movement of surface water and to measure water runoffs from rain and snow, as well as the flow rates of streams and rivers. 4. Hazards of uranium People who live and work near hazardous waste sites, uranium mines and phosphate industry are more affected than normal people. Studies show that crops and water in surrounding areas of waste sites of uranium are very dangerous for health of people. Scientists have detected that natural levels of uranium has no effect on human body. However, chemical effects may occur after the uptake of large amounts of uranium and these can cause health effects such as: • reactive airway disease, • neurological abnormalities, • kidney stones and chronic kidney pain, • rashes, • vision degradation and night vision losses, • gum tissue problems, • lymphoma, • various forms of skin and organ cancer, • neuro-psychological disorders, • birth defects in offspring
4.1 Uranium Analysis We use radioactivity to analyse uranium. Radioactivity analysis of samples was carried out by plancheting known volume of the samples, drying under IR lamp followed by determination of radioactivity using GM counters. GM counter was calibrated with standard sources prior to estimation of samples. Accuracy of GM counter was estimated using standard sources and was found to be 5% expressed in terms of percentage error. Coefficient of variance was found to be in the order of 1.5–2% indicating the reproducible nature of the work.[1] [1]Phytoremediation of 137cesium and 90strontium from solutions and low-level nuclear waste by Vetiveria zizanoides Ecotoxicology and Environmental Safety 69 (2008) 306–311 Shraddha Singha, Susan Eapena, Vidya Thoratb, C.P. Kaushikb, Kanwar Rajb, S.F. D’Souza
Location
Baghalchur is small town in Dera Ghazi Khan District, Punjab, Pakistan. Baghalchur is the site of abandoned Uranium mines now being used as a nuclear dump. The resident of the area are bitterly opposed to the nuclear dump being used by Pakistan Atomic Energy Commission (PAEC).
The area has been categorised by the Asian Development Bank as among the most backward parts of Pakistan. And its fate remains unchanged despite playing a vital role in the country's ambitious nuclear programme by providing a major chunk of the raw material.
Pakistan Atomic Nuclear Energy Commission took out the uranium from Baghalchur area between 1978 and 2006 for the nuclear energy and this process was stopped in 2000 but the nuclear wastes continue to bring other nuclear plants to dump in Baghalchur against which the local people filed an application into the court.
The uranium mines can be seen unprotected while heaps of sand and material left in the leaching process of uranium are found lying in open along the natural watercourses of the area.
From: http://www.chowrangi.com/a-nuclear-dump-in-dera-ghazi-khan.html
Quotation Roland Piquepaille writes
"Nuclear bombs can kill people even if they're not used”
4.2 How uranium wastes are different from other wastes types Uranium ores have the specific issue of radioactivity, and uranium mine wastes are invariably radioactive. This property differentiates uranium mine wastes from other mine waste types. For example, gold mine tailings contain cyanide, and the cyanide can be destroyed using natural, naturally enhanced or engineering techniques. Sulfidic wastes have the potential to oxidize, and oxidation of sulfidic wastes can be curtailed using covers. In contrast, the decay of radioactive isotopes and the associated release of radioactivity cannot be destroyed by chemical reactions, physical barriers or sophisticated engineering methods. Therefore, appropriate disposal and rehabilitation strategies of radioactive uranium mine wastes have to ensure that these wastes do not release radioactive substances into the environment and cause significant environmental harm.
4.3 Methods to Remediate the Situation
• By keeping the heaps of uranium dumps out of the Bio-zones of environment. • Radiochemical analysis of the environment. • A complete medical check up of the residents of the area to ascertain effects of radiation to know severity of the situation. • We deal with a company to produce electricity from uranium nuclear wastes with the process of pellets formation. • To keep uranium wastes into the deep protected caves using covered containers. • By using bacterial spray which utilizes uranium wastes as food. • By remediation through planting the plants which can take up the uranium wastes through roots. • By preserving the uranium keeping barrels into the deep valleys of sea
Note: This project is time consuming so it is divided into different groups and our group will concentrate on remediation of uranium wastes through bacteria.
4.4 Is it True that Bacteria use Uranium as Food? Recent Research conducted in Canada shows that bacteria living below 2,8 km of earth crust are found living. It is thought that bacteria living here so much deep rely on the radioactive uranium to convert water molecules to useable energy.
Pratt, Princeton University Geo-microbiologist Tullis Onstatt and Former graduate student Li-Hung Lin (the paper's lead author, now at National Taiwan University) and colleague’s present evidence that the bacterial communities are indeed permanent -- apparently millions of years old -- and depend not on sunlight but on radiation from uranium ores for their existence
4.5 Remediation of a situation by bacteria Heavy metal pollution has become one of the most serious environmental problems today. Bio-sorption, using biomaterials such as bacteria, fungi, yeast and algae, is regarded as a cost-effective biotechnology for the treatment of high volume and low concentration complex wastewaters containing heavy metal(s) in the order of 1 to 100 mg/L. 4.6 Factors affecting uptake of uranium Uptake of uranium wastes by bacteria depends upon many factors. Among those many are related to pH, temperature and humidity levels. Different bacteria show Different response to these factors. 4.7 List of bacteria which can be used to remediate the situation Among the promising bio-sorbents for heavy metal removal which have been researched during the past decades, Saccharomyces cerevisiae has received increasing attention due to the unique nature in spite of its mediocre capacity for metal uptake compared with other fungi. S. cerevisiae is widely used in food and beverage production, is easily cultivated using cheap media, is also a by-product in large quantity as a waste of the fermentation industry, and is easily manipulated at molecular level. The state of the art in the field of bio-sorption of heavy metals by S. cerevisiae not only in China, but also worldwide, is reviewed in this paper, based on a substantial number of relevant references published recently on the background of bio-sorption achievements and development. Characteristics of S. cerevisiae in heavy metal bio-sorption are extensively discussed. The yeast can be studied in various forms for different purposes. Metal-binding capacity for various heavy metals by S. cerevisiae under different conditions is compared. Lead and uranium, for instances, could be removed from dilute solutions more effectively in comparison with other metals. The yeast bio-sorption largely depends on parameters such as pH, the ratio of the initial metal ion and initial biomass concentration, culture conditions, presence of various ligands and competitive metal ions in solution and to a limited extent on temperature. An assessment of the isotherm equilibrium model, as well as kinetics was performed. The mechanisms of bio-sorption are understood only to a limited extent. Elucidation of the mechanism of metal uptake is a real challenge in the field of bio-sorption. Various mechanism assumptions of metal uptake by S. cerevisiae are summarized
5. Name of bacteria which we used to remediate the situation? The sulfate reducing bacterium, Desulfovibrio desulfuricans can initiate uranium precipitation from solution via direct enzymatic reduction. Additionally, separation of heavy metals from solution can occur via indirect sulfide-mediated precipitation. This study was conducted to evaluate the influence of anions (sulfate, nitrate), heavy metals (zinc, nickel and copper) and organics (acetate, malonate, oxalate and citrate) on the enzymatic reduction of U(VI) by this bacterium. Furthermore, methods were evaluated to selectively precipitate uranium or heavy metals from test solutions. Selective precipitation can significantly lower disposal costs by reducing the volume of mixed-waste sludge produced during treatment. Results indicated that sulfate/nitrate concentrations up to 5000 mg/l did not appreciably interfere with U(VI) reduction, however, anion levels greater than 10,000 mg/l significantly slowed the rate of U(VI) reduction. U(VI) was readily reduced by the bacterium when 10 mg/l of Zn or Ni was present, but Cu inhibited uranium reduction. U(VI) was reduced rapidly in the presence of a monodentate organic ligand (acetate) whereas reduction was slower in the presence of multidentate ligands. Initial results from selective precipitation experiments indicated two potential treatment approaches for isolating either uranium or the test heavy metals using D. desulfuricans. The first method involved free energy differences for U(VI) and sulfate reduction, while the second method involved complexation of reduced uranium by a chelator during metal–sulfide precipitation.
5.1 Picture of the bacterium
5.2 Details about the Bacterium Desulfovibrio is a genus of Gram negative sulfate-reducing bacteria. Some species of Desulfovibrio are capable of transduction. Desulfovibrio species are commonly found in aquatic environments with high levels of organic material, as well as in water-logged soils and form major community members of extreme oligotrophic habitats such as deep granitic fractured rock aquifers. Like other sulfate-reducing bacteria, Desulfovibrio was long considered to be obligately anaerobic. This is not strictly correct: while growth may be limited, these bacteria can survive in O2-rich environments. Some Desulfovibrio species have in recent years been shown to have bioremediation potentials for toxic radio-nuclides such as uranium by a reductive bioaccumulation process (http://en.wikipedia.org/wiki/Desulfovibrio).
Scientific Classification of Desulfovibrio
Kingdom Bacteria Phylum Protobacteria
Class Delta Proteobacteria
Order Desulfovibrionales
Family Desulfovibrionaceae
Genus Desulfovibrio Species D. desulfuricans D. gigas D. salixigens D. vulgaris
5.3 How this bacterium utilizes the uranium Is a versatile bacterium that can use a variety of organic compounds and metals as electron acceptors for respiration?
5.4 Application of this bacterium to the polluted site or remediation in the reactor A pilot scale constructed wetland for treatment of seepage water from uranium mining was planned, built and operated. The pilot plant was designed for treatment of 5 m3 per hour. The system consists of 4 basins and 1 lagoon. The feasibility of treatment of seepage water from uranium mining in constructed wetlands was proven by the operation of the pilot plant. A series of robustness investigations was conducted. A pilot scale constructed wetland for treatment of seepage water from uranium mining was planned, built and operated. New results show a promising technique for cleaning up uranium from some of the most severely contaminated areas by harnessing the powers of microbes. The use of living organisms to clean up toxic waste is a safe and cost-effective solution to the problem of uranium contamination.
Wastewater was dumped in four unlined settling pits. When production ceased, lab officials drained the ponds, filled them with dirt and paved a parking lot the size of four football fields to cover the site. The quantities are enormous: more than 475 billion gallons of contaminated groundwater; 75 million cubic meters of contaminated sediments; and 3 million cubic meters of leaking buried waste. The cleanup program has a budget of $220 billion and a timeline of more than 70 years to develop and implement solutions. This is the largest remediation effort of its type, and possibly the largest environmental cleanup ever attempted in Pakistan. Among the most common contaminants are radioactive metals. These have spread over areas miles wide, making it impractical to store the dirt in closed containers or build barriers to separate the groundwater from drinking water. Uranium sticks to soil, making it impossible to remove efficiently by pumping contaminated groundwater to the surface and treating it there (where its removal creates another disposal problem). But uranium also doesn't stick well enough to soil—over time, it dissolves into the water and can be transported in the groundwater to surface waters, where it is a threat to wildlife and water supplies. In humans, uranium causes kidney damage and cancer as discussed before.
6. Discussion During the times nuclear related actions have been carried on in many corners of the world without thinking, knowing and caring about consequences it will have in the nature later on. Nowadays seriousness of these actions is well understood and it is known that these kinds of practises will result in diseases and problems in living organisms on the earth e.g. kidney damage and cancer. Though development is going into the right direction there is still quite a bit to do for the world, free from negative impacts of nuclear waste. But there is hope. Although nuclear waste has very hazardous impacts on all the life on the earth there has been made findings which help getting problems caused by nuclear waste on a safe level. Both plants and bacteria have been studied and discussed. As examples of natural ways to purify soil, contaminated by nuclear waste, “Sunflower” and “Vetiver grass” has given good results in reducing Sr (Strontium) and Cs (Cesium) concentrations when prevailing circumstances are suitable (http://www.sciencedirect.com). Also bacteria (on which our team is concentrating) and yeast usable for remediation of sites polluted by nuclear waste has been found. One thing which plays an important role is cost-effectiveness and it has been shown that products which are found in nature meet these requirements. When hearing about these naturally purifying methods it may change picture of nuclear power a shade to a positive direction and giving hope to get areas clean where nuclear accidents have taken place. Processes to clean soil and groundwater won’t be happening in a day or two e.g. a project in U.S. where largeness of contamination was noticed after a long time has been assumed to take up to 70 years! But it still shows that case like this can be solved though taking time and quite a lot indeed. Of course the case in U.S. is exceptional and remediation in normal cases can be reacted faster to and with a smaller burden.
7. Results Researches to handle nuclear waste by using natural means have been done in many places in the world like U.S.A, China, Germany etc. All these studies give a positive picture of this kind of study. Even some sites which are contaminated by waste known to be very difficult to handle and has bad reputation are possible to bring back. Research of microbial reduction of soluble Uranium (U VI) to insoluble Uranite in groundwater by sulphate reducing bacteria SRB (consists of many different organisms) was carried out in China. In this experience were used serum bottles containing viable cells. Studies were done at different pH levels 2.0 – 6.0 cleaning up Uranium contaminated ground water from 12.9 % up to 99.4 % respectively. It was found that the most of the removal occurred during the first 48 hours but at pH of 6.0, removal was nearly 100 % after 72 hours. It was also noticed that little concentrations of Copper (≤10 mg/l) or Zink (≤20 mg/l) had no influence on Uranium reduction but when Copper concentration exceeded 15 mg/l the Uranium reduction stopped. Sulphate concentration ≤ 4000 mg/l had no impact on uptake whereas concentration of 5000 ≥ slowed down uptake significantly.
Microorganisms Cell number (ml−1) Denitrifying bacteria (DNB) 7.61×103 Acetogenic bacteria (AB) ND Methane producing bacteria (MB) 3.07×104 Sulfate reducing bacteria (SRB) 4.54×109
Desulfoibrio (D. desulfuricans, D. vulgaris) 107–108 Desulfobulbus (D. elongates, D. propionicus) 104–106 Desulfobacter (D. multivorans) 103–104 Desulfobacterium (D. autotrophicum, D. vacuolatum) 102–104 Desulfococcus (D. Posgatei) 102–103 Desulfotomaculum (D. nigrificans, D. orientis) 102–103 Desulfosarcina (D. variabilis) 101–102
Table 7.1. Composition of the micro organisms used in the U(VI) bio-reduction experiment
Figure 7.1. Uranium reduction at different pH levels.
Figure 7.2, uranium reduction at different Sulphate concentrations. (http://www.sciencedirect.com)
In another research made in U.S. biological reduction of Uranium was also studied. Ground water concentrations were at level of 50 mg/l and originated from mill tailings sites and from a laboratory from where Uranium concentration in water was 11 mg/l. In this case Uranium level was also reduced by using sulphate reducing bacteria whose growth was stimulated by ethanol and trimetaphosphate.
Fig 7.3, reduction of uranium in groundwaters amended with ethanol and trimetaphosphate at 24°C.
In this research uranium concentration succeeded to decrease in all the experiments but one to a level which is under a level of groundwater protection standard of U.S. (44 µg/l). The case where this level wasn’t achieved was groundwater from a mill tailing site. Uranium reduction in water from the tailing site was 90 % after 4 weeks achieving level of 5 mg/l at 24 C. This research couldn’t provide a clear tool to reduce concentration further. Reduction of uranium by sulfide is possible, but this process is relatively slow and it was actually speculated that the presence of carbonate and bicarbonate (being common anions in groundwater) in groundwater inhibits uranium reduction by sulfide to a lower levels (http://www.sciencedirect.com).
Also other researches have been carried out. E.g. researchers at Stanford and Oak Ridge National Laboratory in U.S have used subterranean microbial populations to reduce Uranium to safe levels and immobilize it. In this case ethanol was added to the population to speed up the process and to bind Uranium to soil particles and thus prevented to get to the groundwater. According to the researchers immobilized form of Uranium will stick to the soil at least thousands of years. These researchers were working to enhance a situation on a site where nuclear weapons were built in the early 1950s and thereby soil and ground water got contaminated.
Manchester University, in turn, made a study about a yeast Saccharomyces cerevisiae which was found to uptake different kinds of heavy metals and giving good results in Lead and Uranium uptake. There are still many issues which affect the uptake rate like pH, the ratio of the initial metal ion and initial biomass concentration, culture conditions, presence of various ligands and competitive metal ions in solution and to a limited extent on temperature. Results indicated that sulfate/nitrate concentrations up to 5000 mg/l did not appreciably interfere with U(VI) reduction, however, anion levels greater than 10,000 mg/l significantly slowed the rate of U(VI) reduction. U(VI) was readily reduced by the bacterium when 10 mg/l of Zn or Ni was present, but Cu inhibited uranium reduction.
8. Conclusion Bacteria capable of reducing uranium can be found in groundwater and soils with different chemical composition. The uranium reducers are primarily sulphate-reducers and can be stimulated by addition of nutrients to groundwater with high concentrations of sulphate. Ethanol together with trimetaphosphate yielded the highest rates of sulphate and uranium reduction. The uranium-reducers can also be stimulated in groundwater with low sulphate concentration. Addition of iron sulphate may be necessary in iron- and sulphate-poor groundwater/soil systems to precipitate enough iron sulphide to protect uranite from re-oxidation in oxygenated groundwater when rainwater seeping into the groundwater. (http://www.sciencedirect.com).
As uranium remediation is being worked toward a bioremediation strategy that will work in the field, researchers must design a mechanism to deal with competing organisms in the soil. Some organisms might sequester the free phosphate which means laboratory experiments need to be adjusted to real situations to test if bio-remediation of uranium can really hit through (http://news.bio-medicine.org).
10. References http://www.springerlink.com/content/r30720q175852628/
http://www.accessmylibrary.com/coms2/summary_0286-9139915_ITM
http://www.physorg.com/news67270244.html
http://news-service.stanford.edu/news/2006/may24/criddle-052406.html
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