Quantitative analysis of cake characteristics based on SEM imaging during coagulation-ultrafiltration process

  • Zhenbei WangEmail author
  • Shaoyin Peng
  • Jun NanEmail author
  • Zilin Wang
Research Article


Cake formed by flocs is a crucial factor to affect membrane fouling during coagulation-ultrafiltration process. To investigate the role of floc properties on cake, cake characteristics under various coagulant dosage conditions were calculated by scanning electron microscope (SEM) imaging. Results found that one SEM image with × 5000 magnification could accurately estimate cake porosity with relative error lower than 5.00% for all conditions, whereas more SEM images with × 10,000 magnification or × 20,000 magnification should be applied to calculate cake porosity precisely. This could be explained by different pore information of SEM images with various magnifications. Compared to single SEM image with × 10,000 magnification and × 20,000 magnification, single SEM image with × 5000 magnification contained the most comprehensive pore information and slightly overestimated pore area for pore smaller than 0.4 μm2 due to lower resolution. To verify feasibility by SEM image evaluating cake characteristics, cake porosity calculated by SEM image and Carman-Kozeny equation were analyzed. The results showed that cake porosity estimated by these two methods were nearly the same, proving the feasibility of this method. Moreover, with the increase of coagulant dosage, cake porosity presented similar variation with floc average size, indicating that floc average size was likely to dominate cake porosity in this study. For pore characteristics, pore average characteristic length and pore average area were in accordance with floc fractal dimension, whereas pore fractal dimension and pore amount were consistent with floc average size. This gives specific information about the relation between floc properties and cake characteristics.


Coagulation-ultrafiltration process SEM imaging Magnification Floc properties Cake characteristics 



Comments and suggestions from anonymous reviewers are greatly acknowledged.

Funding information

This research was supported by the State Key Laboratory of Urban Water Resource and Environment (Harbin Institute of Technology) (grant no. 2012DX07).

Supplementary material

11356_2019_6678_MOESM1_ESM.docx (963 kb)
ESM 1 (DOCX 962 kb)


  1. Baveye P, Boast CW, Ogawa S, Parlange JY, Steenhuis T (1998) Influence of image resolution and thresholding on the apparent mass fractal characteristics of preferential flow patterns in field soils. Water Resour Res 34:2783–2796CrossRefGoogle Scholar
  2. Bubakova P, Pivokonsky M, Filip P (2013) Effect of shear rate on aggregate size and structure in the process of aggregation and at steady state. Powder Technol 235:540–549CrossRefGoogle Scholar
  3. Buetehorn S, Utiu L, Kuppers M, Blumich B, Wintgens T, Wessling M, Melin T (2011) NMR imaging of local cumulative permeate flux and local cake growth in submerged microfiltration processes. J Membrane Sci 371:52–64CrossRefGoogle Scholar
  4. Chakraborti RK, Gardner KH, Atkinson JF, Benschoten JEV (2003) Changes in fractal dimension during aggregation. Water Res 37:873–883CrossRefGoogle Scholar
  5. Chen Y, Dong BZ, Gao NY, Fan JC (2007) Effect of coagulation pretreatment on fouling of an ultrafiltration membrane. Desalination 204:181–188CrossRefGoogle Scholar
  6. Cheng XX, Zhou WW, Li PJ, Ren ZX, Wu DJ, Luo CW, Tang XB, Wang JL, Liang H (2019) Improving ultrafiltration membrane performance with pre-deposited carbon nanotubes/nanofibers layers for drinking water treatment. Chemosphere 234:545–557CrossRefGoogle Scholar
  7. Choi YH, Kim HS, Kweon JH (2008) Role of hydrophobic natural organic matter flocs on the fouling in coagulation-membrane processes. Sep Purif Technol 62:529–534CrossRefGoogle Scholar
  8. Feng LJ, Wang WY, Feng RQ, Zhao S, Dong HY, Sun SL, Gao BY, Yue QY (2015) Coagulation performance and membrane fouling of different aluminum species during coagulation/ultrafiltration combined process. Chem Eng J 262:1161–1167CrossRefGoogle Scholar
  9. Gao W, Liang H, Ma J, Han M, Chen ZL, Han ZS, Li GB (2011) Membrane fouling control in ultrafiltration technology for drinking water production: a review. Desalination 272:1–8CrossRefGoogle Scholar
  10. Gao LW, Minakata D, Wei ZG, Spinney R, Dionysiou DD, Tang CJ, Chai LY, Xiao RY (2019) Mechanistic study on the role of soluble microbial products in surfact radical-mediated degradation of pharmaceuticals. Environ Sci Technol 53:342–353CrossRefGoogle Scholar
  11. He WP, Nan J, Li HY, Li SN (2012) Characteristic analysis on temporal evolution of floc size and structure in low-shear flow. Water Res 46:509–520CrossRefGoogle Scholar
  12. Jarvis P, Jefferson B, Gregory J, Parsons SA (2005) A review of floc strength and breakage. Water Res 39:3121–3137CrossRefGoogle Scholar
  13. Kimura K, Hane Y, Watanabe Y, Amy G, Ohkuma N (2004) Irreversible membrane fouling during ultrafiltration of surface water. Water Res 38:3431–3441CrossRefGoogle Scholar
  14. Liu YF, He GH, Li BJ, Hu ZW, Ju J (2012) A comparison of cake properties in traditional and turbulence promoter assisted microfiltration of particulate suspensions. Water Res 46:2535–2544CrossRefGoogle Scholar
  15. Lv Y, Xiao KK, Yang JK, Zhu YW, Pei KY, Yu WB, Tao SY, Wang H, Liang S, Hou HJ, Liu BC, Hu JP (2019) Correlation between oxidation-reduction potential values and sludge dewaterability during pre-oxidation. Water Res 155:96–105CrossRefGoogle Scholar
  16. Marroquin M, Vu A, Bruce T, Powell R, Wickramasinghe SR, Husson SM (2014) Location and quantification of biological foulants in a wet membrane structure by cross-sectional confocal laser scanning microscopy. J Membrance Sci 453:282–291CrossRefGoogle Scholar
  17. Miao R, Wang L, Deng DX, Li SS, Wang JX, Liu TT, Zhu M, Lv YT (2017) Evaluating the effects of sodium and magnesium on the interaction processes of humic acid and ultrafiltration membrane surfaces. J Membrane Sci 526:131–137CrossRefGoogle Scholar
  18. Park PK, Lee CH, Lee S (2006) Permeability of collapsed cakes formed by deposition of fractal aggregates upon membrane filtration. Environ Sci Technol 40:2699–2705CrossRefGoogle Scholar
  19. Park PK, Lee CH, Lee S (2007) Determination of cake porosity using image analysis in a coagulation-microfiltration system. J Membrane Sci 293:66–72CrossRefGoogle Scholar
  20. Saeki D, Matsuyama H (2017) Ultrathin and ordered stacking of silica nanoparticles via spin-assisted layer-by-layer assembly under dehydrated conditions for the fabrication of ultrafiltration membranes. J Membrane Sci 523:60–67CrossRefGoogle Scholar
  21. Sharak AZ, Samimi A, Mousavi SA, Bozarjamhari RB (2014) Investigation of membrane preparation condition effect on the PSD and porosity of the membranes using a novel image processing technique. J Appl Polym Sci 131:1001–1007CrossRefGoogle Scholar
  22. Shen XT, Maa JPY (2016) A camera and image processing system for floc size distributions of suspended particles. Mar Geol 376:132–146CrossRefGoogle Scholar
  23. Shi YF, Yang JK, Yu WB, Zhang SN, Liang S, Song J, Xu Q, Ye N, He S, Yang CZ, Hu JP (2015) Synergetic conditioning of sewage sludge via Fe2+/persulfate and skeleton builder: Effect on sludge characteristics and dewaterability. Chem Eng J 270:572–581CrossRefGoogle Scholar
  24. Shirato M, Aragaki T, Ichimura K, Ootsuji N (1971) Porosity variation in filter cake under constant-pressure filtration. J Chem Eng Jpn 4:172–177CrossRefGoogle Scholar
  25. Wang ZB, Nan J, Yao M, Yang YM (2017a) Effect of additional polyaluminum chloride and polyacrylamide on the evolution of floc characteristics during floc breakage and re-growth process. Sep Purif Technol 173:144–150CrossRefGoogle Scholar
  26. Wang ZB, Nan J, Yao M, Yang YM, Zhang XF (2017b) Insight into the combined coagulation-ultrafiltration process: the role of Al species of polyaluminum chlorides. J Membrane Sci 529:80–86CrossRefGoogle Scholar
  27. Wei ZS, Li W, Zhao DY, Seo Y, Spinney R, Dionysiou DD, Wang Y, Zeng WZ, Xiao RY (2019) Electrophilicity index as a critical indicator for the biodegradation of the pharmaceuticals in aerobic activated sludge processes. Water Res 160:10–17CrossRefGoogle Scholar
  28. Wibisono Y, Yandi W, Golabi M, Nugraha R, Cornelissen ER, Kemperman AJB, Ederth T, Nijmeijer K (2015) Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: a novel platform for eco-friendly biofouling mitigation. Water Res 71:171–186CrossRefGoogle Scholar
  29. Xiao RY, Gao LW, Wei ZS, Spinney R, Luo S, Wang DH, Dionysiou DD, Tang CJ, Yang WC (2017) Mechanistic insight into degradation of endocrine disrupting chemical by hydroxyl radical: An experimental and theoretical approach. Environ Pollut 231:1446–1452CrossRefGoogle Scholar
  30. Xiao RY, Liu K, Bai L, Minakata D, Seo Y, Göktaş RK, Dionysiou DD, Tang CJ, Wei ZS, Spinney R (2019) Inactivation of pathogenic microorganisms by sulfate radical: Present and future. Chem Eng J 371:222–232CrossRefGoogle Scholar
  31. Xu XY, Gao BY (2012) Effect of shear conditions on floc properties and membrane fouling in coagulation/ultrafiltration hybrid process-the significance of Alb species. J Membrane Sci 415:153–160CrossRefGoogle Scholar
  32. Xu WY, Gao BY, Mao RR, Yue QY (2011) Influence of floc size and structure on membrane fouling in coagulation-ultrafiltration hybrid process-The role of Al13 species. J Hazard Mater 193:249–256CrossRefGoogle Scholar
  33. Xu QH, Ye Y, Chen V, Wen XH (2015) Evaluation of fouling formation and evolution on hollow fibre membrane: effects of ageing and chemical exposure on biofoulant. Water Res 68:182–193CrossRefGoogle Scholar
  34. Yan ZS, Liu B, Qu FS, Ding A, Liang H, Zhao Y, Li GB (2017) Control of ultrafiltration membrane fouling caused by algal extracellular organic matter (EOM) using enhanced Al coagulation with permanganate. Sep Purif Technol 172:51–58CrossRefGoogle Scholar
  35. Yao M, Nan J, Li QG, Zhan D, Chen T, Wang ZB, Li HY (2015a) Effect of under-dosing coagulant on coagulation-ultrafiltration process for treatment of humic-rich water with divalent calcium ion. J Membrane Sci 495:37–47CrossRefGoogle Scholar
  36. Yao M, Nan J, Chen T, Zhan D, Li QG, Wang ZB, Li HY (2015b) Influence of flocs breakage process on membrane fouling in coagulation/ultrafiltration process-Effect of additional coagulant of poly-aluminum chloride and polyacrylamide. J Membrane Sci 491:63–72CrossRefGoogle Scholar
  37. Yu WZ, Li GB, Xu YP, Yang X (2009) Breakage and re-growth of flocs formed by alum and PACl. Powder Technol 189:439–443CrossRefGoogle Scholar
  38. Yu WZ, Gregory J, Campos LC (2011) Breakage and re-growth of flocs: effect of additional doses of coagulant species. Water Res 45:6718–6724CrossRefGoogle Scholar
  39. Yu WB, Yang JK, Shi YF, Song J, Shi Y, Xiao J, Li C, Xu XY, He S, Liang S, Wu X, Hu JP (2016) Roles of iron species and pH optimization on sewage sludge conditioning with Fenton's reagent and lime. Water Res 95:124–133CrossRefGoogle Scholar
  40. Yu WZ, Campos LC, Graham N (2016a) Application of pulsed UV-irradiation and pre-coagulation to control ultrafiltration membrane fouling in the treatment of micro-polluted surface water. Water Res 107:83–92CrossRefGoogle Scholar
  41. Yu Y, Zhao CW, Yu L, Li P, Wang T, Xu Y (2016b) Removal of perfluorooctane sulfonates from water by a hybrid coagulation-nanofiltration process. Chem Eng J 289:7–16CrossRefGoogle Scholar
  42. Yu WB, Yang JK, Tao SU, Shi YF, Yu JW, Lv Y, Liang S, Xiao KK, Liu BC, Hou HJ, Hu JP, Wu X (2017) A comparatively optimization of dosages of oxidation agents based on volatile solids and dry solids content in dewatering of sewage sludge. Water Res 126:342–350CrossRefGoogle Scholar
  43. Yu WB, Wen QQ, Yang JK, Xiao KK, Zhu YW, Tao SY, Lv Y, Liang S, Fan W, Zhu SY, Liu BC, Hou HJ, Hu JP (2019) Unraveling oxidation behaviors for intracellular and extracellular from different oxidants (HOCl vs. H2O2) catalyzed by ferrous iron in waste activated sludge dewatering. Water Res 148:60–69CrossRefGoogle Scholar
  44. Zhao BQ, Wang DS, Li T, Chow CWK, Huang C (2010) Influence of floc structure on coagulation-microfiltration performance: effect of Al speciation characteristics of PACls. Sep Purif Technol 72:22–27CrossRefGoogle Scholar
  45. Zheng DB, Andrews RC, Andrews SA, Taylor-Edmonds L (2015) Effects of coagulation on the removal of natural organic matter, genotoxicity, and precursors to halogenated furanones. Water Res 70:118–129CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.College of Environmental Science and EngineeringBeijing Forestry UniversityBeijingPeople’s Republic of China
  2. 2.Skate Key Laboratory of Urban Water Resource and Environment, School of EnvironmentHarbin Institute of TechnologyHarbinPeople’s Republic of China
  3. 3.Tianjin Academy of Environmental SciencesTianjinPeople’s Republic of China

Personalised recommendations