|Year : 2013 | Volume
| Issue : 1 | Page : 32-37
Dissolved uranium, 226 Ra in the mine water effluent: A case study in Jaduguda
NK Sethy, VN Jha, SK Sahoo, PM Ravi, RM Tripathi
Department of Atomic Energy, Bhabha Atomic Research Centre, Health Physics Division, Environmental Studies Section, Health Physics Unit, Jaduguda, Jharkhand, India
|Date of Web Publication||21-Nov-2013|
N K Sethy
Health Physics Unit, Bhabha Atomic Research Centre, Po-Jaduguda Mines, East Singhbhum - 832 102, Jharkhand
Source of Support: None, Conflict of Interest: None
Effluent water from uranium mines, mill tailings ponds were studied for dissolved radionuclide. The concentration of uranium and 226 Ra in untreated effluent water was found to be elevated. The concentration of dissolved radionuclide in the adjacent aquatic streams and river were found to be of lower than the authorized prescribed limit provided by Indian regulatory agencies. The removal process of dissolved radionuclide in the effluent treatment plant is found to be effective with an average decontamination efficiency of >95% for both uranium and 226 Ra. The uranium mining and ore processing activity has not significantly modified the aquatic environment due to effective effluent management system.
Keywords: Effluent, mining, radium, uranium
|How to cite this article:|
Sethy N K, Jha V N, Sahoo S K, Ravi P M, Tripathi R M. Dissolved uranium, 226 Ra in the mine water effluent: A case study in Jaduguda. Radiat Prot Environ 2013;36:32-7
|How to cite this URL:|
Sethy N K, Jha V N, Sahoo S K, Ravi P M, Tripathi R M. Dissolved uranium, 226 Ra in the mine water effluent: A case study in Jaduguda. Radiat Prot Environ [serial online] 2013 [cited 2020 Mar 28];36:32-7. Available from: http://www.rpe.org.in/text.asp?2013/36/1/32/121824
| Introduction|| |
Effluent water from mine, tailings pond and ore processing facility contains toxic metals and radioactive contaminates. In case of uranium mining industry radioactive contaminants such as 226 Ra and natural uranium are expected to be present in the effluent water at elevated level. In the absence of adequate control measures, it may reach to the environment in toxic levels. Discharge of contaminated mine effluents to streams and seepage from tailings ponds can create a source of ground water contamination. Seepage of contaminants from two tailings pond contributed an estimated 2400 curies of uranium radium and thorium to the ground water in Grant Mineral Belt, New Mexico.  Waters with radium concentration above 1.0 kBq/m 3 were found in 43 out of 65 coal mines in Upper Silesian Coal Basin. 
Uranium ore processing facility at Jaduguda adopts hydrometallurgy technique [Figure 1] using concentrated sulfuric acid as leaching media and pyrolusite as oxidant. The H 2 SO 4 leaching of uranium ore leaches 85-95% of uranium  from ore. Even though, only <1% of radium in ore leached  during the processing of ore the activity concentration in effluent is elevated due to high specific activity. Most of the mine effluent water after treatment is recycled in the mill processing circuit, but a substantial quantity of effluent water still remains unused and released to the environment. The effluent is treated for removal of radionuclide and metals in effluent treatment plant (ETP) before release to the environment. The flow diagram of uranium ore processing and treatment of effluent is presented in [Figure 1]. In the tailings pond the tailings allowed to consolidate by gravitational settling and the supernatant effluent water is sent to ETP.
|Figure 1: Uranium ore processing and mine effluent treatment at Jaduguda|
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In ETP the effluent is treated with BaCl 2 ,, for removal of 226 Ra by coprecipitation with barium sulfate. The effluent water is further treated with lime to increase the pH to precipitate radio toxins in hydroxide forms. At elevated pH radionuclide such as Th, Po and Pb are converted to insoluble as hydroxides. Hence, their activity concentration in liquid effluent is in less and remains below the detection level. Furthermore, the presence of elevated level of Fe 3+ in effluents act as carrier (Fe (OH) 3 ) for radionuclide such as Po at elevated pH  The addition of lime to effluent during treatment results in formation of insoluble hydroxide of heavy metals and radionuclide existing as cations at pH 7-9. 
The treated effluent quality as per the national regulatory standards is discharged into the nearby Juria-Gara stream. The Juria stream feeds into the Gara River (a tributary of Suvernrekha River) and is ultimately discharged into the Suvernrekha River  Suvarnrekha River is the major aquatic body receiving the industrial effluent from this area. Several studies , were carried out regarding release of mine water effluent to aquatic ecosystem and uptake of radionuclide and metals by aquatic plants and fish species around Jaduguda uranium mine.
This paper considers the assessment of radionuclide in the effluent water released to the environment as well as the effectiveness of effluent treatment process.
The Proterozoic Jaduguda uranium (-Cu-Fe) deposit in the Singhbhum shear zone, Eastern India hosts the oldest and most productive uranium mine.  Jaduguda and Bhatin uranium mines (Long. 22°30', Lat. 86°20') are situated in the Jharkhand state of India. The area [Figure 2] is well-known for its heterogeneous high mineral deposits. The geological futures of the area is well-documented  Many copper, nickel and uranium mining activities are continuing since last five decades  . It receives >1000 mm of rain fall annually with a maximum temperature in summer is >45° C and minimum is <7 0 C during winter. There are several uranium mines and a centralized uranium mill for processing of uranium ore present in Jaduguda. The average ore grade is about 0.05% U 3 O 8 .
| Materials and Methods|| |
Samples were collected from the discharge end of uranium mining facility sites effluent channel, residual effluent from tailings pond and inlet and outlet effluent from ETP. Water samples from upstream and downstream of water body receiving the mine water effluent were collected trough out the period of 1 year. The Suvarnrekha upstream is present at a distance of 3.5 km from uranium facility and downstream is in the same river at 6 km down in the flow direction of water. Representative effluent samples were collected by the help of a proportionate sampler [Figure 3]. The sampler as described in earlier  studies consist of a wheel of diameter 120 cm and average speed of 7 rpm, capable of run by the force of the flowing effluent stream. The wheel rotates about the horizontal axis and the movement is made nearly frictionless by the help of ball bearing mechanism. The instrument runs by the force of the flowing stream without any external power source. A small sample collecting device (0.5 ml) is attached to the moving wheel serves to collect the sample from the effluent stream. The proportionate sampler thereby collects 5.04 l of composite sample in a day. The samples were collected every 24 h. The 24 h sample was brought to the laboratory, filtered using Whatman-42 filter paper and preserved in acidic medium. Samples collected over a month were mixed thoroughly and 5 l sample was taken out representing the proportionate sample of a month.
Analysis of U
Uranium in effluent samples was carried out by fluorometric technique. Chemically separated uranium is fused with a fusion mixture (NaF-Na 2 CO 3 ) and subjected to ultraviolet (UV) radiation in a fluorimeter. Intensity of fluorescence is proportional to the amount of uranium present in the sample. 3650 Ǻ excitation and 5546 Ǻ fluorescence wavelength is unique to uranium , A known quantity of leached sample was evaporated to near dryness. 1 ml of conc-H 2 SO 4 was added and evaporated till white fumes disappear. Sample was refluxed with 20 ml 0.25 N H 2 SO 4 and filtered and transferred to a separating funnel. After cooling, 10 ml of alamine in benzene was added (2% alamine in 98% Benzene). The separating funnel was shaken for 1 min and aqueous layer drained out. The organic layer (0.1 ml) was transferred on platinum planchet. 250 mg of NaF-Na 2 CO3 (15:85) fusion mixture was added and fused at 800°C for 3 min. Cooled and fluorescence intensity measured in ECIL (Electronic Corporation of India limited), make fluorimeter. 
Standard (1 μg/ml) and blank were processed simultaneously and uranium was estimated by using the formula:
The uranium content of the original sample was obtained from the above equation by further applying the sampling parameters. The measurement of uranium by UV-fluorimeter in environmental samples is in agreement with similar studies using nitrogen based laser flourimeter. ,
Analysis of 226 Ra
226 Ra is estimated by allowing buildup of its daughter 222 Rn for a known period (~2 weeks). ,,, The in-built radon was collected in a scintillation cell and counted after equilibrium (between radon and its progeny) is attained.  Leached sample aliquot (50 ml) or concentrated water sample was loaded in radon bubbler. The radon already present in the solution was removed by using evacuation pump. After ensuring the radon free aliquot, the solution was allowed to retain for 2 weeks or more depending on the expected level of radium in the sample. During this period, 226 Ra through alpha decay leads to the formation of its progeny 222 Rn. The in-built radon was collected in a previously evacuated scintillation cell. The scintillation cell was left for minimum 200 min for 222 Rn and its progeny equilibrium. The scintillation cell was coupled with a photo multiplier tube. Alpha counts were recorded for a desired period in order to get counts above 95% confidence level. From the counts obtained, the radon activity transferred from the bubbler to the cell was calculated using the equation.
Where, C is the net counts obtained after subtraction of the background,
E, the efficiency of the cell (75%),
t, the counting delay in minutes (>200 min),
T, the counting duration in minutes (10 min),
θ, the buildup period in minutes (>28 days),
λ, the decay constant of 222 Rn (1.258 Χ 10 −4 /min) and
V is the volume of the sample.
The 226 Ra content of the original sample was obtained from the above equation by further applying the correction for sampling parameters.
Analytical method was tested using International Atomic Energy Agency reference standards in an earlier work done from the same laboratory. 
| Results and Discussion|| |
The dissolved radionuclide content in water samples from aquatic streams and effluent from ETP are presented in [Table 1]. Juria stream which is the primary recipient of the effluent in the environment showed low concentration of uranium and 226 Ra. The connecting Gara stream also showed low concentration of dissolved radionuclide in water samples. Water samples from Suvarnrekha River, the major aquatic body of the study area showed insignificant concentration of dissolved radionuclide in both upstream and downstream location. There are several copper mines and one copper processing unit is in operation in this region. Copper tailings and effluents containing uranium series long lived radionuclides are directly disposed into the river bank. This may be the reason for the higher concentration of uranium in Suvarnrekha downstream than ETP outlet [Table 1] . However, outlet of ETP showed a drastically decrease in dissolved radionuclide than untreated effluent in the inlet of ETP. Activity concentration of dissolved radionuclide in untreated effluent water from mines, mill, tailings ponds and treated effluent of ETP is presented in [Table 2]. Effluent water from Jaduguda mine showed concentration of uranium in the range of 94-843.3 μg/l with a geometric mean (GM) of 357.4 μg/l and geometric standard deviation (GSD) 1.9. 226 Ra was varied from 40 to 1706 mBq/l with GM of 371.3 mBq/l and GSD 2.6. The mine water from Bhatin uranium mine also showed dissolved radionuclide in elevated level. The GM concentration of dissolved uranium and 226 Ra observed was 334.1 μg/l and 182 mBq/l respectively. The mean concentration of dissolved 226 Ra in Bhatin mine water was less than the dissolved uranium in Jaduguda mine effluent water. In uranium mill effluent the GM concentration of uranium and 226 Ra were observed was 91.7 μg/l and 221 mBq/l respectively.
|Table 1: Uranium and 226Ra in water body receiving mine effluent and effluent treatment plant (2011)|
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The dissolved radionuclide concentration in effluent water reported in different studies world-wide is presented in [Table 3]. The concentration of dissolved uranium and 226 Ra in seepage effluent from Kerr-Mcgee mine discharge  and uranium mine effluent, New Mexico were found to be much elevated than the present study. Analysis of dissolved radionuclide data in the inlet and outlet of ETP [Figure 4] during the study period found an average decontamination efficiency of >95% for both uranium and 226 Ra.
|Table 3: Comparison of the present study with the similar studies world-wide|
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| Conclusions|| |
Following conclusions can be made from this study:
- Effluent from mines and processing plant contains dissolved radionuclide at elevated levels.
- The treatment of effluent at ETP effectively removes uranium as well as radium to acceptable levels.
- The high efficiency of decontamination (>95%) of ETP for uranium and 226 Ra bearing effluent contributes the low concentration of these contaminates in the recipient Juria stream, Gara stream and Suvarnrekha River.
- The dilution available in the Suvarnrekha River also further reduces the concentration of dissolved radionuclide.
It can be concluded that the release of treated effluent to the environment has not affected the Juria-Gara-Suvarnrekha aquatic system.
| Acknowledgment|| |
Thanks are due to Shri D.N.Sharma, Director, Health, Safety and Environment group, BARC for his encouragement during this study. Support and assistance provided by Shri N.M. Soren and A.K. Dwevedi of H.P. Unit, Jaduguda are duly ackonowldged.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]