The simultaneous removal of turbidity and humic substances from water using the enhanced coagulation process

Document Type : Original Article


1 Environmental Health Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran

2 Department of Environmental Health Engineering, School of Health, Qazvin University of Medical Sciences, Qazvin, Iran

3 Lecturer, Environmental Health Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran

4 Department of Environmental Health Engineering, School of Health, Baqiyatallah University of Medical Sciences, Tehran, Iran

5 Kurdistan Environmental Health Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran


This study aimed to investigate the efficiency of the enhanced coagulation (EC) process for the simultaneous removal of turbidity and humic substances (HS) from raw water from the Sanandaj Water Treatment Plant (SWTP). This study was conducted on a laboratory scale using a jar test device and ferric chloride (FeCL3) as the coagulant. Accordingly, the effects of pH and coagulant dosage variations on the simultaneous removal efficiency of turbidity and humic substances in the enhanced coagulation process were investigated. Furthermore, certain parameters including the total organic carbon (TOC), dissolved organic carbon (DOC), ultraviolet absorbance (UV254), and chemical oxygen demand (COD) were determined as the indices of the humic substances and turbidity in the water samples. The results of the raw water analysis showed that the mean values of TOC, DOC, UV254, COD, and turbidity parameters were 4.41 mg/L, 4.11 mg/L, 16.47 1/cm, 15 mg/L, and 4.37 NTU, respectively. Moreover, the results of the present study showed that the average efficiency of the enhanced coagulation process in the removal of TOC, DOC, UV254, COD, and turbidity was 65%, 62%, 70%, 69%, and 93%, respectively. Accordingly, the EC process using FeCL3 coagulant is a suitable, cost-effective, and highly efficient method for the simultaneous removal of turbidity and humic substances from water. Furthermore, this process can be used as an applicable method in SWTP as well as in other similar water treatment plants.


  1. Huang X, Gao B, Yue Q, Wang Y, Li Q. Effect of Si/Ti molar ratio on enhanced coagulation performance, floc properties and sludge reuse of a novel hybrid coagulant:polysilicate titanium sulfate. Desalination. 2014;352: 150-7
  2. Patsios SI, Sarasidis VC, Karabelas AJ. A hybrid photocatalysis–ultrafiltration continuous process for humic acids degradation. Separation and Purification Technology. 2013;104: 333-41
  3. Mahvi AH, Maleki A, Rezaee R, Safari M. Reduction of humic substances in water by application of ultrasound waves and ultraviolet irradiation. Iranian Journal of Environmental Health Science & Engineering. 2009;6: 233-40.
  4. Siddiqui KS, Ertan H, Charlton T, Poljak A, Khaled AD, Yang X, et al. Versatile peroxidase degradation of humic substances: Use of isothermal titration calorimetry to assess kinetics, and applications to industrial wastes. Journal of biotechnology. 2014;178: 1-11.
  5. Kavurmaci SS, Bekbolet M. Photocatalytic degradation of humic acid in the presence of montmorillonite. Applied Clay Science. 2013;75: 60-6.
  6. Hu WC, Wu CD, Jia AY, Chen F. Enhanced coagulation for treating slightly polluted algae-containing raw water of the Pearl River combining ozone pre-oxidation with polyaluminum chloride (PAC). Desalination and Water Treatment. 2014;56(6): 1698-703.
  7. Joseph L, Flora JRV, Park Y-G, Badawy M, Saleh H, Yoon Y. Removal of natural organic matter from potential drinking water sources by combined coagulation and adsorption using carbon nanomaterials. Separation and Purification Technology. 2012;95: 64-72.
  8. Yan M, Wang D, Qu J, Ni J, Chow CWK. Enhanced coagulation for high alkalinity and micro-polluted water: the third way through coagulant optimization. Water research. 2008;42(8-9): 2278-86.
  9. Yan M, Wang D, Ni J, Qu J, Yan Y, Chow CWK. Effect of polyaluminum chloride on enhanced softening for the typical organic-polluted high hardness North-China surface waters. Separation and Purification Technology. 2008;62(2): 401-6.
  10. Ren Z, Graham N. Treatment of Humic Acid in Drinking Water by Combining Potassium Manganate (Mn (VI)), Ferrous Sulfate, and Magnetic Ion Exchange. Environmental Engineering Science. 2015;32(3): 175-8.
  11. Maleki A, Safari M, Shahmoradi B, Zandsalimi Y, Daraei H, Gharibi F. Photocatalytic degradation of humic substances in aqueous solution using Cu-doped ZnO nanoparticles under natural sunlight irradiation. Environmental Science and Pollution Research. 2015;22(21): 16785-80.
  12. Maleki A, Safari M, Rezaee R, Cheshmeh Soltani RD, Shahmoradi B, Zandsalimi Y. Photocatalytic degradation of humic substances in the presence of ZnO nanoparticles immobilized on glass plates under ultraviolet irradiation. Separation Science and Technology. 2016;51(14): 2484-9.
  13. Song JJ, Huang Y, Nam S-W, Yu M, Heo J, Her N, et al. Ultrathin graphene oxide membranes for the removal of humic acid. Separation and Purification Technology. 2015;144: 162-7.
  14. Ng LY, Mohammad AW, Rohani R, Hairom NHH. Development of a nanofiltration membrane for humic acid removal through the formation of polyelectrolyte multilayers that contain nanoparticles. Desalination and Water Treatment. 2015;57(17): 7627-36.
  15. Ulu F, Barışçı S, Kobya M, Särkkä H, Sillanpää M. Removal of humic substances by electrocoagulation (EC) process and characterization of floc size growth mechanism under optimum conditions. Separation and Purification Technology 2014;133: 246-53.
  16. Sudoh R, Islam MS, Sazawa K, Okazaki T, Hata N, Taguchi S, et al. Removal of dissolved humic acid from water by coagulation method using polyaluminum chloride (PAC) with calcium carbonate as neutralizer and coagulant aid. Journal of Environmental Chemical Engineering. 2015;3(2): 770-4.
  17. Amin MM, Hashemi H, Safari M, Rezaei Z. Evaluating the Amount of Residual Aluminum from Conventional and Enhanced Coagulation Using Poly-aluminum Chloride in Refined Water. Health System Research. 2012;8(3): 449-55.[In Persian]
  18. Xie J, Wang D, van Leeuwen J, Zhao Y, Xing L, Chow CWK. pH modeling for maximum dissolved organic matter removal by enhanced coagulation. Journal of Environmental Sciences. 2012;24(2): 276-83.
  19. Amin M, Safari M, Maleki A, Ghasemian M, Rezaee R, Hashemi H. Feasibility of humic substances removal by enhanced coagulation process in surface water. International Journal of Environmental Health Engineering. 2012;1: 29.
  20. Yan M, Wang D, Ni J, Qu J, Ni W, Van Leeuwen J. Natural organic matter (NOM) removal in a typical North-China water plant by enhanced coagulation: Targets and techniques. Separation and Purification Technology. 2009;68(3): 320-7.
  21. Saltnes T, Eikebrokk B. Contact filtration of humic waters: performance of an expanded clay aggregate filter (Filtralite) compared to a dual anthracite/sand filter. Water Science and Technology:Water Supply. 2002;2(5-6): 17-23.
  22. Kabsch-Korbutowicz M. Effect of Al coagulant type on natural organic matter removal efficiency in coagulation/ultrafiltration process. Desalination. 2005;185(1-3): 327-33.
  23. Yan M, Wang D, You S, Qu J, Tang H. Enhanced coagulation in a typical North-China water treatment plant. Water research. 2006;40(19): 3621-7.
  24. Matilainen A, Vepsäläinen M, Sillanpää M. Natural organic matter removal by coagulation during drinking water treatment: A review. Advances in Colloid and Interface Science. 2010;159(2): 189-97.
  25. Watson K, Farre MJ, Knight N. Enhanced coagulation with powdered activated carbon or MIEX® secondary treatment: A comparison of disinfection by-product formation and precursor removal. Water research. 2015;68: 454-66.
  26. Rezaee R, Maleki A, Jafari A, Mazloomi S, Zandsalimi Y, Mahvi AH. Application of response surface methodology for optimization of natural organic matter degradation by UV/H 2 O 2 advanced oxidation process. Journal of Environmental Health Science and Engineering. 2014;12(1): 67.
  27. Federation WE, Association APH. Standard methods for the examination of water and wastewater. American Public Health Association (APHA): Washington, DC, USA 2005.
  28. Volk C, Bell K, Ibrahim E, Verges D, Amy G, LeChevallier M. Impact of enhanced and optimized coagulation on removal of organic matter and its biodegradable fraction in drinking water. Water research. 2000;34(12): 3247-57.
  29. Uyak V, Toroz I. Disinfection by-product precursors reduction by various coagulation techniques in Istanbul water supplies. Journal of Hazardous Materials. 2007;141(1): 320-8.
  30. Rizzo L, Belgiorno V, Gallo M, Meric S. Removal of THM precursors from a high-alkaline surface water by enhanced coagulation and behaviour of THMFP toxicity on D. magna. Desalination. 2005;176(1-3): 177-88.
  31. Yan M, Wang D, Yu J, Ni J, Edwards M, Qu J. Enhanced coagulation with polyaluminum chlorides: role of pH/alkalinity and speciation. Chemosphere. 2008;71(9): 1665-73.
  32. Ciner F, Ozer S. Removal of Natural Organic Matter from Water by Enhanced Coagulation. Journal of Selcuk University Natural and Applied Science. 2013: 256-67.
  33. Edzwald J. Coagulation in drinking water treatment: Particles, organics and coagulants. Water Science and Technology 1993;27(11): 21-35.
  34. Alizadeh M, Bazrafshan E, Mahvi AH, KordMostafapour F, Ghahremani E. Efficiency of Pistaciaatlantica seed extract as natural coagulant in the removal of Reactive Red 198 dye from aqueous solution. Scientific Journal of Kurdistan University of Medical Sciences 2014;19(1): 124-34.