Hardness and chloride removal in dewatering system: Modeling and optimization of electrochemical reaction

Document Type : Research Paper


1 Department of Mining Engineering, Higher education complex of Zarand, Kerman, Iran

2 Department of Environment, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran


The electrocoagulation (EC) process is a novel approach in the mining industry, especially to recycle water in the dewatering system of a mineral processing plant. In this research, the electrocoagulation process was studied to remove the hardness and chloride ions from concentrate thickener overflow water under different operating conditions: retention time (5–15 min), initial pH (4–10), current density (41.6–166.6 A/m2) and electrode type (Fe, Fe-Al, Al). Four factors with three levels with the D-optimal response surface design were applied for optimization. As a result, the optimal situation for the electrocoagulation process was characterized by a retention time of 15 min, initial pH of 9.08, the current density of 139.59 A/m2, and electrode type Fe-Al. In this situation, the maximum removal efficiency of hardness (60.11%) and chloride (98.38%) were yielded with a desirability value of 0.989. These results illustrated the effectiveness of the EC process as an influence method for the removal of hardness and chloride in terms of separation.


Main Subjects

[1] Gunson, A. J., Klein, B., Veiga, M., Keevil, N. B. (2010, June). Estimating global water withdrawals due to copper mining. In 2nd international congress on water management in the mining industry (pp. 9-11).
[2] Brown, E. T. (2003). Water for a sustainable minerals industry− a review. Proceedings of water in mining 2003.
[3]. Bangerter, P., Dixon, R., Villegas, M. (2010, June). Improving overall usage of water in mining-A sustainable development approach. In 2nd international congress on water management in the mining industry (pp. 9-11).
[4] Gunson, A., Klein, B., Veiga, M., Dunbar, S. (2012). Reducing mine water requirements. Journal of cleaner production, 21(1), 71-82.
[5] Statcan. (2008). Industrial water use-2005. 16-401-X, Minister of Industry. Ottawa.
[6] Rudman, M., Paterson, D.A., Simic, K. (2010). Efficiency of raking in gravity thickeners. International journal of mineral processing, 95(1-4), 9–30.
[7] Ebrahimzadeh, G.M., Soltani, G.A., Aghajani, S.A. (2013a).  Simulation of a semi-industrial pilot plant thickener using CFD approach. International journal of mining science and technology. 23(1), 63–68.
[8] Stickland, A.D., Burgess, C., Dixon, D.R., Harbour, P.J., Scales, P.J., Studer, L.J., Usher, S.P. (2008). Fundamental dewatering properties of wastewater treatment sludges from filtration and sedimentation testing. Chemical engineering science, 63(21), 5283–5290.
[9] White, R.B., Sutalo, I.D., Nguyen, T. (2003). Fluid flow in thickener feedwell models. Minerals engineering, 16(3), 145–50.
[10] Ebrahimzadeh, G.M., Soltani, G.A., Aghajani, S.A., Abdollahi, H. (2013b). Modeling industrial thickener using computational fluid dynamics (CFD), a case study: Tailing thickener in the Sarcheshmeh copper mine. International journal of mining science and technology, 23(6), 885–892.
[11] Chen, X., Chen, G., Yue, P.L. (2000). Separation of pollutants from restaurant wastewater by electrocoagulation. Separation and purification technology, 19(1-2), 65–76.
[12] Yeon, K.H., Song, J.H., Moon, S.H. (2004). A study on stack configuration of continuous electrodeionization for removal of heavy metal ions from the primary coolant of a nuclear power plant. Water research, 38(10), 1911–1921.
[13] Song, J.H., Yeon, K.H., Cho, J., Moon, S.H. (2005). Effect of operating parameters on the reverse osmosis-electrodeionization performance in the production of high purity water. Korean journal of chemical engineering, 22(1), 108–114.
[14] Park, J.S., Song, J.H., Yeon, K.H., Moon, S.H. (2007). Removal of hardness ions from tap water using electromembrane processes. Desalination, 202(1-3), 1–8.
[15] Fu, L., Wang, J., Su, Y. (2009). Removal of low concentrations of hardness ions from aqueous solutions using electrodeionization process. Separation and purification technology, 68(3), 390–396.
[16] Jurenka, B. (2010). Lime softening. reclamation managing water in the west.
[17] Zhi, S., Zhang, S. (2014). A novel combined electrochemical system for hardness removal. Desalination, 349, 68–72
[18] Moosavirad, S.M. (2017). Treatment and operation cost analysis of greywater by electrocoagulation and comparison with coagulation process in mining areas. Separation and Purification technology, 52(3), 1742–1750.
[19] Ferreira, A.M., Marchesiello, M., Thivel, P.X. (2013). Removal of copper, zinc and nickel present in natural water containing Ca2+ and HCO3- ions by electro coagulation. Separation and purification technology, 107, 109–117.
[20] Kamaraj, R., Ganesan, P., Lakshmi, J., Vasudevan, S. (2012). Removal of copper from water by electrocoagulation process—effect of alternating current (AC) and direct current (DC). Environmental science and pollution research, 20(1), 399–412.
[21] Holt, P.K., Barton,G.W., Mitchell,C.A. (2006).The future for electrocoagulation as a localiced water treatment technology. Chemosphere, 23(2), 355-367.
[22] Zeng, Y., Yang, C.Z., Pu, W.H., Zhang, X.L. (2007). Removal of silica from heavy oil wastewater to be reused in a boiler by combining magnesium and zinc compounds with coagulation. Desalination, 216, 147–159.
[23] Koo, C.H., Mohammad, A.W., Suja, F. (2011). Recycling of oleochemical wastewater for boiler feed water using reverse osmosis membranes — a case study. Desalination, 271(1–3), 178-186.
[24] Parrott, R., Pitts, H. (2011). Chloride stress corrosion cracking in austenitic stainless steel. Health and safety executive. Harpur hill. buxton. Derbyshire.
[25] Yaghmaeian, K., Martinez, S.S., Hoseini, M., Amiri, H. (2016). Optimization of As (III) removal in hard water by electrocoagulation using central composite design with response surface methodology. Desalination and water treatment, 57(57), 27827–27833.
[26] Caroline, D., Marina, E., Ricardo, K., Héctor, C.G. (2007). Crossed mixture design and multiple response analysis for developing complex culture medium used in recombinant protein production. Chemo metrics and intelligent laboratory systems, 86, 1–9.
[27] Yin, H., Chen, Z., Gu, Z., Han, Y. (2009). Optimization of natural fermentative medium for selenium-enriched yeast by D-optimal mixture design. LWT-food science and technology, 42, 327–331.
[28] Kobya, M., Can, O.T., Bayramoglu, M. (2003). Treatment of textile wastewaters by electrocoagulation using iron and aluminum electrodes. Journal of hazardous materials, 100(1–3), 163–178
[29] Zhao, S.H., Huang, G., Cheng, G., Wang, Y., Fu, H. (2014). Hardness, COD and turbidity removals from produced water by electrocoagulation pretreatment prior to Reverse Osmosis membranes. Desalination, 344, 454–462
[30] LI, Z.Q., LI, J., Zhang, L.B., Peng, J.H., Wang, S.X., MA, A.y., Wang, B.B. (2015). Response surface optimization of process parameters for removal of F and Cl from zinc oxide fume by microwave roasting. Transactions of nonferrous metals society of China, 25(3), 973−980.
[31] Acharya, S., Sharma, S. K., Chauhan, G., Shree, D. (2018). Statistical optimization of electrocoagulation process for removal of nitrates using response surface methodology. Indian chemical engineer, 60(3), 269-284.
[32] Asaithambi, P., Abdul-Aziz, A., Wan-Daud, W.M.A.B. (2016). Integrated ozone—electrocoagulation process for the removal of pollutant from industrial effluent: Optimization through response surface methodology. Chemical engineering and processing, 105, 92-102.
[33] Olmez, T. (2009). The optimization of Cr (VI) reduction and removal by electrocoagulation using response surface methodology. Journal of hazardous materials, 162(2–3), 1371–1378.
[34] Mu., Y., Zheng, X.J., Yu, H.Q. (2009). Determining optimum conditions for hydrogen production from glucose by an anaerobic culture using response surface methodology (RSM). International journal of Hydrogen energy, 34(19), 7959–7963
[35] Montgomery, D. C. (2017). Design and analysis of experiments. John wiley and sons.
[36] Demim, S., Drouiche, N., Aouabed, A., Benayad, T., Dendene-Badache, O., Semsari, S. (2013). Cadmium and nickel: assessment of the physiological effects and heavy metal removal using a response surface approach by L gibba. Ecological engineering, 61, 426–435.
[37] Myers, R. H., Montgomery, D. C., Anderson-Cook, C. M. (2016). Response surface methodology: process and product optimization using designed experiments. John Wiley and Sons.
[38] Ke-di, Y., Xian-jin, Y.E., Jing, S.U., Hai-feng, S.U., Yun-fei, L., Xiao-yan, L.Ü., Yan-xuan, W. (2013). Response surface optimization of process parameters for reduction roasting of low-grade pyrolusite by bagasse. Transactions of nonferrous metals society of China, 23(2), 548−555.
[39] Emamjomeh, M., Sivakumar, M. (2009). Denitrification using a monopolar electrocoagulation flotation (ECF) Process. Journal of environmental management, 91, 516–522.
[40] Ghanim, A.N. (2013). Application of response surface methodology to optimize Nitrate removal from wastewater by electrocoagulation, International journal of scientific andengineering research, 4(10), 1410–1416.
[41] Chou, W.L., Wang, C.T., Huang, K.Y. (2009). Effect of operating parameters on indium (III) ion removal by iron electrocoagulation and evaluation of specific energy consumption. Journal of hazardous materials, 167(1–3), 467–474.
[42] Drouiche, N., Aoudj, S., Hecini, M., Ghaffour, N., Lounici, H., Mameri, N. (2009). Study on the treatment of photovoltaic wastewater using electrocoagulation: fluoride removal with aluminum electrodes—characteristics of products. Journal of hazardous materials, 169(1–3), 65–69.
[43] Karichappan, T., Venkatachalam, S., Jeganathan, P.M. (2014). Optimization of electrocoagulation process to treat grey wastewater in batch mode using response surface methodology. Journal of environmental health science and engineering, 12(29), 1–8.
[44] Ghernaout, D., Badis, A., Kellil, A., Ghernaout, B. (2008). Application of electrocoagulation in Escherichia coli culture and two surface waters. Desalination, 219(1–3), 118–125.
[45] Cañizares, P., Martínez, F., Lobato, J., Rodrigo, M.A. (2007). Break-up of oil-in-water emulsions by electrochemical techniques. Journal of hazardous materials, 145(1–2), 233–240.
[46] Malakootian, M., Mansoorian, H.J., Moosazadeh, M. (2010). Performance evaluation of electrocoagulation process using iron-rod electrodes for removing hardness from drinking water. Desalination, 255(1–3), 67–71.
[47] Sridhar, R., Sivakumar, V., Immanuel, V.P., Maran, J.P. (2011). Treatment of pulp and paper industry bleaching effluent by electrocoagulation process. Journal of hazardous materials, 186(2–3), 1495–1502.
[48] Nanseu-Njiki, C.P., Tchamango, S.R., Ngom, P.C., Darchen, A., Ngameni, E. (2009). Mercury (II) removal from water by electrocoagulation using aluminium and iron electrodes. Journal of hazardous materials, 168(2–3), 1430–1443.
[49] Tir, M., Moulai-Mostefa, N. (2008). Optimization of oil removal from oily wastewater by electrocoagulation using response surface method. Journal of hazardous materials, 158(1), 107–115.
[50] Chen, G. (2004). Electrochemical technologies in wastewater treatment. Separation and purification technology, 38(1), 11–41.
[51] Chen, X., Chen, G., Yue, P.L. (2002). Novel electrode system for electroflotation of wastewater. Environmental science and technology, 36(4), 778–783.
[52] Huda, N., Raman, A.A.A., Bello, M.M., Ramesh, S. (2017). Electrocoagulation treatment of raw landfill leachate using iron-based electrodes: Effects of process parameters and optimization. Journal of environmental management, 204, 75–81.
[53] Moosavirad S. M., Hassanzadeh Sablouei A. (2020). Removal of cadmium from the leaching solution using electrocoagulation. Journal of environment and water engineering, 6(4), 415–429.