This article presented two-staged chemical precipitation for radioactive wastewater decontamination by using chemical agents. The total amount of radioactive wastewater was $35m^3$, and main radionuclides were Cs-137, Cs-134, and Co-60. Initial radioactivity concentration of the liquid wa...
This article presented two-staged chemical precipitation for radioactive wastewater decontamination by using chemical agents. The total amount of radioactive wastewater was $35m^3$, and main radionuclides were Cs-137, Cs-134, and Co-60. Initial radioactivity concentration of the liquid waste was 2264, 17, and 9 Bq/L for Cs-137, Cs-134 and Co-60, respectively. Potassium ferrocyanide, nickel nitrate, and ferrum nitrate were selected as chemical agents at high pH levels 8-10 according to the laboratory jar tests. After the process, radioactivity was precipitated as sludge at the bottom of the tank and decontaminated clean liquid was evaluated depending on discharge limits. By this precipitation method decontamination factors were determined as 66.5, 8.6, and 9 for Cs-137, Cs-134, and Co-60, respectively. By using the potassium ferrocyanide, about 98% of the Cs-137 was removed at pH 9. At the bottom of the tank, radioactive sludge amount from both stages was totally $0.98m^3$. It was transferred by sludge pumps to cementation unit for solidification. By chemical processing, 97.2% of volume reduction was achieved. The potassium ferrocyanide in two-staged precipitation method could be used successfully in large-scale applications for removal of Cs-137, Cs-134, and Co-60.
This article presented two-staged chemical precipitation for radioactive wastewater decontamination by using chemical agents. The total amount of radioactive wastewater was $35m^3$, and main radionuclides were Cs-137, Cs-134, and Co-60. Initial radioactivity concentration of the liquid waste was 2264, 17, and 9 Bq/L for Cs-137, Cs-134 and Co-60, respectively. Potassium ferrocyanide, nickel nitrate, and ferrum nitrate were selected as chemical agents at high pH levels 8-10 according to the laboratory jar tests. After the process, radioactivity was precipitated as sludge at the bottom of the tank and decontaminated clean liquid was evaluated depending on discharge limits. By this precipitation method decontamination factors were determined as 66.5, 8.6, and 9 for Cs-137, Cs-134, and Co-60, respectively. By using the potassium ferrocyanide, about 98% of the Cs-137 was removed at pH 9. At the bottom of the tank, radioactive sludge amount from both stages was totally $0.98m^3$. It was transferred by sludge pumps to cementation unit for solidification. By chemical processing, 97.2% of volume reduction was achieved. The potassium ferrocyanide in two-staged precipitation method could be used successfully in large-scale applications for removal of Cs-137, Cs-134, and Co-60.
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제안 방법
Solidified drums and samples remained for 21 days in the facility for curing. After 21 days, uniaxial compressive strength tests were applied to the samples. Samples for uniaxial compressive strength tests were obtained by preparation of mixtures and by using 50 mm diameter cylindrical molds with a height of 120 mm.
Initial specific radioactivity of the wastewater was determined as 2,264, 17, and 9 Bq/L for Cs-137, Cs-134, and Co-60, respectively, by analyzing of the samples which were taken from the tank. Experimental studies were used for selection of the best chemical precipitation conditions by using jar test. The jar test was applied to all samples, and precipitation sludge of each sample was analyzed by using gamma spectrometry system.
In this study, a spectrometric analysis system was used to determine activity concentrations. The system consisted of a coaxial-type high-purity germanium detector that was linked to a multichannel buffer consisting of an analog-to-digital converter.
Most of the radioactivity was precipitated by chemical agents to the bottom sludge, and a large amount of clean liquid could be discharged. In this study, a two-staged chemical precipitation technique using potassium ferrocyanide, nickel nitrate, and ferrum nitrate were applied to radioactive wastewater. Soluble nickel and ferrocyanide salt solutions were added simultaneously to precipitate Ni2Fe(CN)6 which ion exchanges some of the Ni for Cs.
Experimental studies were used for selection of the best chemical precipitation conditions by using jar test. The jar test was applied to all samples, and precipitation sludge of each sample was analyzed by using gamma spectrometry system. Potassium ferrocyanide, nickel nitrate, and ferrum nitrate were selected as chemical agents at high pH levels 8e10 according to laboratory jar test results.
대상 데이터
Preliminary testing of grout compressive strength is used as a classical method, which is practiced in civil engineering. NX type of cylindrically shaped grout samples with 50 mm diameter and 120 mm height were prepared. The uniaxial compressive strength of the samples was calculated as MPa, and mechanical test results were determined as in the range of 15–25 MPa.
이론/모형
Samples for uniaxial compressive strength tests were obtained by preparation of mixtures and by using 50 mm diameter cylindrical molds with a height of 120 mm. For uniaxial compressive strength tests, procedures were followed according to American Society for Testing and Materials (ASTM C39-86) standard [13]. Preliminary testing of grout compressive strength is used as a classical method, which is practiced in civil engineering.
성능/효과
By this method, transportation of sludge in drums is more economical and safer method than initial transportation of wastewater. Although DF values could be different for each of applications related to main specifications of original liquid waste, this study confirms that removal of radioactive contaminants from wastewater by using potassium ferrocyanide, nickel nitrate, and ferrum nitrate is not only a cost-effective method but also reduces radiological risks as well.
V. Avramenko, A. Voit, A. Golub, V. Dobzhansky, A. Egorin, V. Maiorov, V. Sergienko, S. Shmatko, Y. Korchagin, Hydrothermal reprocessing of liquid radwastes from nuclear power plants, At. Energy 105 (2008) 150-154.
L. Popov, I. Kuleff, R. Djingova, Determination of radiocesium in environmental water samples using copper Ferro(II)cyanide and sodium tetraphenylborate, J. Radioanal. Nuclear Chem. 269 (2006) 203-207.
A. Mollah, A. Begum, M. Rahman, Removal of radionuclides from low-level radioactive liquid waste by precipitation, J. Radioanal. Nuclear Chem. 229 (1998) 187-189.
E. Lee, J. Lim, D. Chung, H. Yang, K. Kim, Selective removal of Cs and Re by precipitation in a $Na_2CO_3-H_2O_2$ solution, J. Radioanal. Nuclear Chem. 284 (2010) 387-395.
J. Mertz, E. Manos, M. Kanatzidis, Selective radionuclide ( $Cs^{+},\, Sr^{2+},\, and\, Ni^{2+}$ ) ion-exchange by $K_{2x}Mg_xSn_{3-x}S_6$ (x0.5-0.95) (KMS-2), Mater. Res. Soc. Symp. Proc. 1265 (2010) 53-58.
G. Ibrahim, Removal of $^{60}Co$ and $^{134}Cs$ radionuclides from aqueous solution using titanium tungstate ion exchanger, Desalin. Water Treat. 13 (2010) 418-426.
C. Xu, L. Yuan, X. Shen, M. Zhai, Efficient removal of cesium ions from aqueous solution using a calix crown ether in ionic liquids: mechanism and radiation effect, Dalton Trans. 39 (2010) 3897-3902.
S. Taj, D. Muhammad, M. Chaudhry, M. Mazhar, Lithium, rubidium and cesium ion removal using potassium iron(III) hexacyanoferrate(II) supported on polymethylmethacrylate, J. Radioanal. Nuclear Chem. 288 (2011) 79-88.
C. Zhang, P. Gu, J. Zhao, D. Zhang, Y. Deng, Research on the treatment of liquid waste containing cesium by an adsorption-microfiltration process with potassium zinc hexacyanoferrate, J. Hazard. Mater. 167 (2009) 1057-1062.
M. Abd El-Latif, M. Elkady, Kinetics study and thermodynamic behavior for removing cesium, cobalt and nickel ions from aqueous solution using nanozirconium vanadate ion exchanger, Desalination 271 (2011) 41-54.
M. Poirier, M. Hay, D. Herman, K. Crapse, G. Thaxton, S. Fink, Removal of sludge heels in Savannah river site waste tanks with oxalic acid, Sep. Sci. Technol. 45 (2010) 1858-1875.
M. Duignan, C. Nash, Removal of cesium from Savannah river site waste with spherical resorcinol formaldehyde ion exchange resin: experimental tests, Sep. Sci. Technol. 45 (2010) 1828-1840.
ASTM, Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens, The American Society for Testing and Materials, 1986. ASTM C39- C86.
M. Ojovan, G. Varlackova, Z. Golubeva, O. Burlaka, Long-term field and laboratory leaching tests of cemented radioactive wastes, J. Hazard. Mater. 187 (2011) 296-302.
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