A Pore-Scale Physical Model for Electric Dewatering of Municipal Sludge Based on Fractal Geometry
Publication: Journal of Environmental Engineering
Volume 149, Issue 3
Abstract
Water in municipal sludge has an electric double layer (EDL), and can be rapidly removed via electroosmosis. However, the understanding of the physical mechanisms of electroosmosis is limited owing to the complex pore structure of sludge porous media, which may restrict the development of electric dewatering (EDW) technology. In this study, the sludge microstructure was measured using the computerized tomography technique and quantitatively characterized using fractal geometry. A new pore-scale physical model for the electroosmotic flow through sludge porous media was developed based on the EDL theory, and the analytical expressions for the electroosmotic flow rate and permeability coefficient were determined. The proposed fractal pore-scale model for electroosmotic flow was validated by comparing it with the measured electroosmotic flow rate using a self-designed EDW device for municipal sludge composed of a hydraulic system and applied electric field. The results show that the electroosmotic flow rate of sludge porous media depends not only on the applied electric field, but also on the sludge microstructure including porosity, maximum pore size, and pore and tortuosity fractal dimensions. However, the correlation between the electroosmotic flow rate and the voltage gradient was usually nonlinear, and became linear only if the tortuosity fractal dimension equaled to one (straight flow path). The electroosmotic permeability coefficient increases with an increase in porosity; however, it is lowered by the increased pore and tortuosity fractal dimensions under a certain porosity. The electroosmosis phenomenon can effectively remove part of the interstitial water and surface water in sludge porous media, and the proposed electroosmotic physical model provides a useful theoretical basis for the development of EDW technology for municipal sludge.
Get full access to this article
View all available purchase options and get full access to this article.
Data Availability Statement
All data, models, and code generated or used during the study appear in the published article.
Acknowledgments
This work was jointly supported by the Natural Science Foundation of China (Grant No. 51876196), Zhejiang Provincial Natural Science Foundation of China (Grant No. LR19E060001), Science and Technology Innovation Leading Talent Project of Special Support Plan for High-level Talents of Zhejiang Province (2021R52056), and Fundamental Research Funds for the Provincial Universities of Zhejiang (Grant No. 2020YW13).
References
Cai, Q. Y., C. H. Mo, Q. T. Wu, Q. Y. Zeng, and A. Katsoyiannis. 2007. “Quantitative determination of organic priority pollutants in the composts of sewage sludge with rice straw by gas chromatography coupled with mass spectrometry.” J. Chromatogr. A 1143 (1–2): 207–214. https://doi.org/10.1016/j.chroma.2007.01.007.
Cao, B., W. Zhang, Y. Du, R. Wang, S. P. Usher, P. J. Scales, and D. Wang. 2018. “Compartmentalization of extracellular polymeric substances (EPS) solubilization and cake microstructure in relation to wastewater sludge dewatering behavior assisted by horizontal electric field: Effect of operating conditions.” Water Res. 130 (Mar): 363–375. https://doi.org/10.1016/j.watres.2017.11.060.
Casagrande, I. L. 1949. “Electro-osmosis in soil.” Géotechnique 1 (3): 159–177. https://doi.org/10.1680/geot.1949.1.3.159.
Glendinning, S. S. G. N., C. K. Mok, D. D. K. N. Kalumba, C. D. F. Rogers, and D. V. L. Hunt. 2010. “Design framework for electrokinetically enhanced dewatering of sludge.” J. Environ. Eng. 136 (4): 417–426. https://doi.org/10.1061/(ASCE)EE.1943-7870.0000159.
Helmholtz, H. V. 1879. “Studien über electrische Grenzschichten.” Ann. Phys. 243 (7): 337–382. https://doi.org/10.1002/andp.18792430702.
Hossein, S., and N. Mohsen. 2020. “Pyrolysis of municipal sewage sludge for bioenergy production: Thermo-kinetic studies, evolved gas analysis, and techno-socio-economic assessment.” Renewable Sustainable Energy Rev. 119 (Mar): 109567. https://doi.org/10.1016/j.rser.2019.109567.
Hunter, R. J. 1981. Zeta potential in colloid science: Principles and applications. New York: Academic Press.
Kobayashi, K., M. Iwata, Y. Hosoda, and H. Yukawa. 1979. “Fundamental study of electroosmotic flow through perforated membrane.” J. Chem. Eng. Jpn. 12 (6): 466–471. https://doi.org/10.1252/jcej.12.466.
Krejcirikova, B., L. M. Ottosen, G. M. Kirkelund, C. Rode, and R. Peuhkuri. 2019. “Characterization of sewage sludge ash and its effect on moisture physics of mortar.” J. Build. Eng. 21 (Jan): 396–403. https://doi.org/10.1016/j.jobe.2018.10.021.
Kuśnierz, M. 2018. “Scale of small particle population in activated sludge flocs.” Water Air Soil Pollution 229 (10): 372. https://doi.org/10.1007/s11270-018-3979-7.
Larue, O., R. J. Wakeman, E. S. Tarleton, and E. Vorobiev. 2006. “Pressure electroosmotic dewatering with continuous removal of electrolysis products.” Chem. Eng. Sci. 61 (14): 4732–4740. https://doi.org/10.1016/j.ces.2006.02.006.
Li, Z. H., Y. Guo, Z. Y. Hang, T. Y. Zhang, and H. Q. Yu. 2020. “Simultaneous evaluation of bioactivity and settleability of activated sludge using fractal dimension as an intermediate variable.” Water Res. 178 (Jul): 115834. https://doi.org/10.1016/j.watres.2020.115834.
Liang, M. C., et al. 2015. “Analysis of electroosmotic characters in fractal porous media.” Chem. Eng. Sci. 127 (May): 202–209. https://doi.org/10.1016/j.ces.2015.01.030.
Liang, M. C. 2019. “A fractal study for the effective electrolyte diffusion through charged porous media.” Int. J. Heat Mass Transfer 137 (Jul): 365–371. https://doi.org/10.1016/j.ijheatmasstransfer.2019.03.141.
Mahmoud, A., and F. A. H. Andrew. 2010. “Electrical field: A historical view of its application and contributions in wastewater sludge dewatering.” Water Res. 44 (8): 2381–2407. https://doi.org/10.1016/j.watres.2010.01.033.
Mahmoud, A., A. F. Hoadley, M. Citeau, J. M. Sorbet, G. Olivier, J. Vaxelaire, and J. Olivier. 2018. “A comparative study of electro-dewatering process performance for activated and digested wastewater sludge.” Water Res. 129 (Feb): 66–82. https://doi.org/10.1016/j.watres.2017.10.063.
Mahmoud, A., J. Olivier, J. Vaxelaire, and A. F. Hoadley. 2011. “Electro-dewatering of wastewater sludge: Influence of the operating conditions and their interactions effects.” Water Res. 45 (9): 2795–2810. https://doi.org/10.1016/j.watres.2011.02.029.
Mitchell, J. K., and K. Soga. 2005. Fundamentals of soil behaviour. 3rd ed. New York: Wiley.
Paillat, T., E. Moreau, P. O. Grimaud, and G. Touchard. 2000. “Electrokinetic phenomena in porous media applied to soil decontamination.” IEEE Trans. Dielectr. Electr. Insul. 7 (5): 693–704. https://doi.org/10.1109/94.879363.
Peng, R., Y. Yang, Y. Ju, L. Mao, and Y. Yang. 2011. “Computation of fractal dimension of rock pores based on gray CT images.” Chin. Sci. Bull. 56 (31): 3346–3357. https://doi.org/10.1007/s11434-011-4683-9.
Pham, A. T., M. Sillanpää, and J. Virkutyte. 2010. “Sludge dewatering by sand-drying bed coupled with electro-dewatering at various potentials.” Int. J. Min. Reclam. Environ. 24 (2): 151–162. https://doi.org/10.1080/17480930903132620.
Qiao, X., Y. Shen, X. Tan, S. Qiu, Z. Jiang, A. P. Sasmito, and P. Xu. 2022. “The correlation between fluid flow and heat transfer of unsaturated shale reservoir based on fractal geometry.” Fractals 30 (3): 2250069. https://doi.org/10.1142/S0218348X22500694.
Qiu, S., M. Yang, P. Xu, and B. Rao. 2020. “A new fractal model for porous media based on low-field nuclear magnetic resonance.” J. Hydrol. 586 (Jul): 124890. https://doi.org/10.1016/j.jhydrol.2020.124890.
Raats, M. H. M., A. J. G. Van Diemen, J. Laven, and H. N. Stein. 2002. “Full scale electrokinetic dewatering of waste sludge.” Colloids Surf., A 210 (2–3): 231–241. https://doi.org/10.1016/S0927-7757(02)00380-1.
Rabie, H. R., A. S. Mujumdar, and M. E. Weber. 1994. “Electroosmotic dewatering of bentonite in thin beds.” Sep. Technol. 4 (3): 180–182. https://doi.org/10.1016/0956-9618(94)80021-9.
Ramadan, B. S., A. D. Farhah, M. Hadiwidodo, and M. A. Budihardjo. 2021. “Recent progress on pressure-driven electro-dewatering (PED) of contaminated sludge.” In Electrokinetic remediation for environmental security and sustainability, edited by A. B. Ribeiro and M. N. Vara Prasad, 629–652. Hoboken: Wiley.
Rao, B., et al. 2021. “Pore-scale model and dewatering performance of municipal sludge by ultrahigh pressurized electro-dewatering with constant voltage gradient.” Water Res. 189 (Feb): 116611. https://doi.org/10.1016/j.watres.2020.116611.
Rao, B., J. Su, J. Xu, S. Xu, H. Pang, Y. Zhang, P. Xu, B. Wu, J. Lian, and L. Deng. 2022a. “Coupling mechanism and parameter optimization of sewage sludge dewatering jointly assisted by electric field and mechanical pressure.” Sci. Total Environ. 817 (Apr): 152939. https://doi.org/10.1016/j.scitotenv.2022.152939.
Rao, B., X. Su, S. Qiu, P. Xu, X. Lu, M. Wu, J. Zhang, Y. Zhang, and W. Dong. 2019. “Meso-mechanism of mechanical dewatering of municipal sludge based on low-field nuclear magnetic resonance.” Water Res. 162 (Oct): 161–169. https://doi.org/10.1016/j.watres.2019.06.067.
Rao, B., G. Wang, and P. Xu. 2022b. “Recent advances in sludge dewatering and drying technology.” Dry. Technol. 40 (15): 3049–3063. https://doi.org/10.1080/07373937.2022.2043355.
Rezaie, A., A. J. Mauron, and K. Beyer. 2020. “Sensitivity analysis of fractal dimensions of crack maps on concrete and masonry walls.” Autom. Constr. 117 (Sep): 103258. https://doi.org/10.1016/j.autcon.2020.103258.
Rice, C., and R. Whitehead. 1965. “Electrokinetic flow in a narrow cylindrical capillary.” J. Phys. Chem. 69 (11): 4017–4024. https://doi.org/10.1021/j100895a062.
Schmid, G. 1951. “Zur Elektrochemie feinporiger Kapillarsysteme: iI Elektroosmose.” Zeitschrift für Elektrochemie und angewandte physikalische Chemie 55 (3): 229–237. https://doi.org/10.1002/bbpc.19510550313.
Shen, Y., P. Xu, S. Qiu, B. Rao, and B. Yu. 2020. “A generalized thermal conductivity model for unsaturated porous media with fractal geometry.” Int. J. Heat Mass Transfer 152 (May): 119540. https://doi.org/10.1016/j.ijheatmasstransfer.2020.119540.
Smoluchowski, M. 1903. “Contribution à la théorie de l’ endosmose électrique et de quelques phenomènes corrélatifs.” Bull. Akad. Sci. Cracovie 8 (Mar): 182–200. https://doi.org/10.1051/jphystap:019040030091201.
Tarleton, E. S., R. J. Wakeman, and Y. Liang. 2003. “Electrically enhanced washing of ionic species from fine particle filter cakes.” Chem. Eng. Res. Des. 81 (2): 201–210. https://doi.org/10.1205/026387603762878665.
Thanh, L. D., D. Jougnot, P. Van Do, A. Mendieta, N. X. Ca, V. X. Hoa, P. M. Tan, and N. T. Hien. 2020. “Electroosmotic coupling in porous media, a new model based on a fractal upscaling procedure.” Transp. Porous Med. 134 (1): 249–274. https://doi.org/10.1007/s11242-020-01444-7.
Tuan, P. A., V. Jurate, and S. Mika. 2008. “Electro-dewatering of sludge under pressure and non-pressure conditions.” Environ. Technol. 29 (10): 1075–1084. https://doi.org/10.1080/09593330802180294.
Tyta, M. 2019. “Assessment of heavy metal pollution and potential ecological risk in sewage sludge from municipal wastewater treatment plant located in the most industrialized region in poland-case study.” Int. J. Environ. Res. Public Health 16 (13): 2430. https://doi.org/10.3390/ijerph16132430.
Vesilind, A. P. 1994. “The role of water in sludge dewatering.” Water Environ. Res. 66 (1): 4–11. https://doi.org/10.2175/WER.66.1.2.
Visigalli, S., A. Turolla, P. Gronchi, and R. Canziani. 2017. “Performance of electro-osmotic dewatering on different types of sewage sludge.” Environ. Res. 157 (Aug): 30–36. https://doi.org/10.1016/j.envres.2017.05.015.
Wang, M. 2012. “Structure effects on electro-osmosis in microporous media.” J. Heat Transfer 134 (5): 051020. https://doi.org/10.1115/1.4005711.
Weijin, G., Z. Zizheng, L. Yue, W. Qingyu, and G. Lina. 2019. “Hydrogen production and phosphorus recovery via supercritical water gasification of sewage sludge in a batch reactor.” Waste Manage. 96 (Aug): 198–205. https://doi.org/10.1016/j.wasman.2019.07.023.
Wheatcraft, S. W., and S. W. Tyler. 1988. “An explanation of scale-dependent dispersity in heterogeneous aquifers using concepts of fractal geometry.” Water Resour. Res. 24 (4): 566–578. https://doi.org/10.1029/WR024i004p00566.
Wójcik, M., and F. Stachowicz. 2019. “Influence of physical, chemical and dual sewage sludge conditioning methods on the dewatering efficiency.” Powder Technol. 344 (Feb): 96–102. https://doi.org/10.1016/j.powtec.2018.12.001.
Wu, R., X. Dai, and X. Chai. 2020. “Critical review on dewatering of sewage sludge: Influential mechanism, conditioning technologies and implications to sludge reutilizations.” Water Res. 180 (Aug): 115912. https://doi.org/10.1016/j.watres.2020.115912.
Xu, P. 2015. “A discussion on fractal models for transport physics of porous media.” Fractals 23 (3): 1530001. https://doi.org/10.1142/S0218348X15300019.
Xu, P., A. S. Mujumdar, A. P. Sasmito, and B. Yu. 2019. “Multiscale modeling of porous media.” In Heat and mass transfer in drying of porous media, edited by P. Xu, A. P. Sasmito, and A. S. Mujumdar, 55–79. Boca Raton, FL: Taylor & Francis.
Yao, S., and J. G. Santiago. 2003. “Porous glass electroosmotic pumps: Theory.” J. Colloid Interface Sci. 268 (1): 133–142. https://doi.org/10.1016/S0021-9797(03)00731-8.
Yu, B. 2008. “Analysis of flow in fractal porous media.” Appl. Mech. Rev. 61 (5): 1239–1249. https://doi.org/10.1115/1.2955849.
Yu, B. M., and P. Cheng. 2002. “A fractal model for permeability of bi-dispersed porous media.” Int. J. Heat Mass Transfer 45 (14): 2983–2993. https://doi.org/10.1016/S0017-9310(02)00014-5.
Yu, B. M., and J. H. Li. 2001. “Some fractal characters of porous media.” Fractals 9 (3): 365–372. https://doi.org/10.1142/S0218348X01000804.
Yukawa, H., H. Chigira, T. Hoshino, and M. Iwata. 1971. “Fundamental study of electroosmotic filtration effect of strength of electric field on flow rate of permeation.” J. Che. Eng. Jpn. 4 (4): 370–376. https://doi.org/10.1252/jcej.4.370.
Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 149 • Issue 3 • March 2023
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Jul 9, 2022
Accepted: Oct 25, 2022
Published online: Dec 30, 2022
Published in print: Mar 1, 2023
Discussion open until: May 30, 2023
ASCE Technical Topics:
- Biological processes
- Dewatering
- Engineering fundamentals
- Engineering materials (by type)
- Environmental engineering
- Flow (fluid dynamics)
- Flow rates
- Fluid dynamics
- Fluid mechanics
- Fractals
- Geometry
- Hydrologic engineering
- Materials engineering
- Mathematics
- Models (by type)
- Municipal water
- Osmosis
- Physical models
- Pollutants
- Porous media
- Sludge
- Waste management
- Waste treatment
- Wastes
- Water (by type)
- Water and water resources
- Water management
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.