DOI QR코드

DOI QR Code

Effect of electrocoagulation on sludge characteristics in EC-MBR

EC-MBR에서 전기응집이 슬러지 특성에 미치는 영향

  • Um, Se-Eun (Department of Nanobiotronics, Hoseo University) ;
  • Chang, In-Soung (Department of Environmental Engineering, Hoseo University)
  • 엄세은 (호서대학교 나노바이오트로닉스학과) ;
  • 장인성 (호서대학교 환경공학과)
  • Received : 2017.09.12
  • Accepted : 2017.12.08
  • Published : 2017.12.31

Abstract

The application of electro-coagulation has been attempted to control the membrane fouling problem in a MBR (Membrane Bio-Reactor). This study examined the effects of the operating parameters (current density and contact time) of the electro-coagulation process on the change in the characteristics of activated sludge. The current density changed from 2.5 to 12, $24A/m^2$, and the contact time was varied from 0 to 2 and 6 hr, respectively. At a current density of $24A/m^2$ and 6 hr of operation, the MLSS changed from 6,800 to 7,000 mg/L (3% increase), but the MLVSS did not increase significantly. After 6 hr of operation, the soluble COD decreased from 71 to 37 mg/L under the $24A/m^2$ condition, from 113 to 67 mg/L under the $12A/m^2$ condition, and from 84 to 80 mg/L under the $2.5A/m^2$ condition. On the other hand, soluble-TN and -TP concentration showed slight changes. The soluble-EPS and Bound-EPS concentration decreased slightly with increasing current density. The membrane filtration performance of activated sludge before and after electro-coagulation was compared. The filtration resistances after electro-coagulation decreased from 6 to 61 %, particularly as the current density and contact time were increased. This indicates that electro-coagulation can be used to control membrane fouling in the MBR process.

전기응집 공정은 MBR (Membrane Bio-Reactor) 공정의 막 오염을 해결하기 위한 일환으로 응용되고 있다. 본 연구는 전기응집 공정의 중요한 운전변수인 전류밀도와 접촉시간에 따른 활성슬러지의 특성 변화에 관한 연구를 수행하였다. 전류밀도를 2.5, 12, $24A/m^2$로, 접촉시간은 0, 2, 6 hr로 변화시켜 가며 활성슬러지의 특성 변화를 관찰하였다. 전류밀도 $24A/m^2$ 조건에서 6시간 동안 MLSS는 6,800에서 7,000 mg/L로 3% 증가하였고, MLVSS는 6,280에서 6,300 mg/L로 큰 변화가 없었다. 다른 전류밀도 조건 하에서도 동일한 경향이 관찰되었다. COD는 전류밀도가 $24A/m^2$일 때 71에서 37 mg/L로 감소하였고, $12A/m^2$일 때는 113에서 67 mg/L로, $2.5A/m^2$일 때는 84에서 80 mg/L로 감소하였다. 반면 TN과 TP는 전반적으로 큰 변화를 보이지 않았다. Soluble-EPS와 Bound-EPS는 전류밀도가 증가할수록 약간 감소하는 경향을 보였다. 전기응집을 거친 활성슬러지로 막 여과를 수행하여 여과성능이 개선되는지 평가하였다. 전기응집을 수행하지 않은 대조군에 비해 총여과저항 ($R_t$)이 6~61% 감소한 것으로 나타났다. 특히 전류밀도와 접촉시간이 증가할수록 막 여과 저항이 감소하는 것을 확인하였다. 이를 통해 전기응집 공정이 MBR 공정의 막 여과 성능 개선에 사용될 수 있음을 확인하였다.

Keywords

References

  1. F. Meng, S. R. Chae, A. Drews, M. Kraume, H. S. Shin, F. Yang, "Recent advances in membrane bioreactors (MBRs): Membrane fouling and membrane material, Water Research, vol. 43, pp. 1489-1512, 2009. DOI: https://doi.org/10.1016/j.watres.2008.12.044
  2. W. Yang, N. Cicek, J. Ilg, "State-of-the-art of membrane bioreactors: Worldwide research and commercial applications in North America", Journal of Membrane Science, vol. 270, pp. 201-211, 2006. DOI: https://doi.org/10.1016/j.memsci.2005.07.010
  3. Z. Wang, Z. Wu, S. Mai, C. Yang, X. Wang, Y. An, Z. Zhou, "Research and applications of membrane bioreactors in China: Progress and prospect", Separation Purification Technology, vol. 62, pp. 249-263, 2008. DOI: https://doi.org/10.1016/j.seppur.2007.12.014
  4. J. Wu, P. Le-Clech, R. M. Stuetz, A. G. Fane, V. Chen, "Effects of relaxation and backwashing conditions on fouling in membrane bioreactor", Journal of Membrane Science, vol.324, pp. 26-32, 2008. DOI: https://doi.org/10.1016/j.memsci.2008.06.057
  5. P. Le-Clech, V. Chen, T. A. G. Fane, "Fouling in membrane bioreactors used in wastewater treatment", Journal of Membrane Science, vol. 284, pp. 17-53, 2006. DOI: https://doi.org/10.1016/j.memsci.2006.08.019
  6. B. R. Lim, K. H. Ahn, K. G. Song, J. W. Cho, "Microbial community in biofilm on membrane surface of submerged MBR: effect of in-line cleaning chemical agent", Water Science Technology, vol. 51, no. 6-7, pp. 201-207, 2005.
  7. M. F. Siddiqui, M. Rzechowicz, H. Winters, A. W. Zularisam, A. G. Fane, "Quorum sensing based membrane biofouling control for water treatment: A review", Journal of Water Process Engineering, vol. 7, pp. 112-122, 2015. DOI: https://doi.org/10.1016/j.jwpe.2015.06.003
  8. A. D. Tafti, S. M. S. Mirzaii, M. R. Andalibi, M. Vossoughi, "Optimized coupling of an intermittent DC electric field with a membrane bioreactor for enhanced effluent quality and hindered membrane fouling", Separation Purification Technology, vol. 152, pp.7-13, 2015. DOI: https://doi.org/10.1016/j.seppur.2015.07.004
  9. M. Hunsom, K. Pruksathorn, S. Damronglerd, H. Vergnes, P. Duverneuil, "Electrochemical treatment of heavy metals ($Cu^{2+},\;Cr^{6+},\;Ni^{2+}$) from industrial effluent and modeling of copper reduction", Water Research, Vol. 39, pp. 610-616, 2005. DOI: https://doi.org/10.1016/j.watres.2004.10.011
  10. N. Meunier, P. Drogui, G. Mercier, J. F. Blais, "Treatment of metal-loaded soil leachates by electrocoagulation", Separation and Purification Technology, vol. 67, pp. 110-116, 2009. DOI: https://doi.org/10.1016/j.seppur.2009.03.040
  11. K. Sadeddin, A. Naser, A. Firas, "Removal of turbidity and suspended solids by electro-coagulation to improve feed water quality of reverse osmosis plant", Desalination, vol. 268, pp. 204-207, 2011. DOI: https://doi.org/10.1016/j.desal.2010.10.027
  12. J. Liu, L. Liu, B. Gao, F. Yang, "Cathode membrane fouling reduction and sludge property in membrane bioreactor integrating electrocoagulation and electrostatic repulsion", Separation and Purification Technology, vol. 100, pp. 44-50, 2012. DOI: https://doi.org/10.1016/j.seppur.2012.08.029
  13. B. Zhu, D. A. Clifford, S. Chellam, "Comparison of electrocoagulation and chemical coagulation pretreatment for enhanced virus removal using microfiltration membranes", Water Research, vol. 39, pp. 3098-3108, 2005. DOI: https://doi.org/10.1016/j.watres.2005.05.020
  14. K. Bani-Melhem, M. Elektorowicz, "Development of a Novel Submerged Membrane Electro-Bioreactor (SMEBR): Performance for Fouling Reduction", Environment Science Technology, vol. 44, pp. 3298-3304, 2010. DOI: https://doi.org/10.1021/es902145g
  15. M. Ben-Sasson, Y. M. Lin, A. Adin, "Electrocoagulation-membrane filtration hybrid system for colloidal fouling mitigation of secondary-effluent", Separation and Purification Technology, vol. 82, pp. 63-70, 2011. DOI: https://doi.org/10.1016/j.seppur.2011.08.020
  16. APHA, AWWA, WEF., Standard Methods for the Examination of Water and Wastewater 19th, pp. 2-53-58, USA, 1995.
  17. Z. Wang, Z. Wu, S. Tang, "Extracellular polymeric substances (EPS) properties and their effects on membrane fouling in a submerged membrane bioreactor", Water Research, vol. 43, pp. 2504-2512, 2009. DOI: https://doi.org/10.1016/j.watres.2009.02.026
  18. O. H. Lowry, N. J. Rosebrough, A. L. Farr, R. J. Randall, "Protein measurement with the folin phenol reagent", Journal of Biological Chemistry, vol. 193, pp. 265-275, 1951.
  19. D. B. Michel, K. A. Gilles, J. K. Hamilton, P. A. Rebers, F. Smith, "Colorimetric Method for Determination of Sugars and Related Substances", Journal of Analytical Chemistry, vol. 28, no. 3, pp. 350-356, 1956. DOI: https://doi.org/10.1021/ac60111a017
  20. G. Chen, "Electrochemical technologies in wastewater treatment", Separation and Purification Technology, vol. 38, pp. 11-41, 2004. https://doi.org/10.1016/j.seppur.2003.10.006
  21. E. Lacasa, P. Canizares, C. saez, F. J. Fernandez, M. A. Rodrig, "Electrochemical phosphates removal using iron and aluminium electrodes", Chemical Engineering Journal, vol. 172, pp. 137-143, 2011. DOI: https://doi.org/10.1016/j.cej.2011.05.080
  22. J. Liu, L. Liu, B. Gao, F. Yang, "Integration of bio-electrochemical cell in membrane bioreactor for membrane cathode fouling reduction through electricity generation", Journal of Membrane Science, vol. 430, pp. 196-202, 2013. DOI: https://doi.org/10.1016/j.memsci.2012.11.046
  23. J. Zhang, H. C. Chua, J. Zhou, A. G. Fane, "Factors affecting the membrane performance in submerged membrane bioreactors", Journal of Membrane Science, vol. 284, pp. 54-66, 2006. DOI: https://doi.org/10.1016/j.memsci.2006.06.022
  24. H. Lin, M. Zhang, F. Wang, F. Meng, B. Q. Liao, H. Hong, J. Chen, W. Gao, "A critical review of extracellular polymeric substances (EPSs) in membrane bioreactors Characteristics, roles in membrane fouling a", Journal of Membrane Science, vol. 460, pp. 110-125, 2014. DOI: https://doi.org/10.1016/j.memsci.2014.02.034
  25. S. Ibeid, M. Elektorowicz, J. A. Oleszkiewicz, "Electro-conditioning of activated sludge in a membrane electro-bioreactor for improved dewatering and reduced membrane fouling", Journal of Membrane Science, vol. 494, pp. 136-142, 2015. DOI: https://doi.org/10.1016/j.memsci.2015.07.051
  26. S. Ibeid, M. Elektorowicz, J. A. Oleszkiewicz, "Impact of electrocoagulation of soluble microbial products on membrane fouling at different volatile suspended solids' concentrations", Environmental Technology, vol. 38(4), pp. 385-393, 2017. DOI: http://dx.doi.org/10.1080/09593330.2016.1195879
  27. L. C. Hua, C. Huang, Y. C. Su, T. N. P. Nguyen, P. C. Chen, "Effects of electro-coagulation on fouling mitigation and sludge characteristics in a coagulation-assisted membrane bioreactor", Journal of Membrane Science, vol. 495, pp. 29-36, 2015. DOI: https://doi.org/10.1016/j.memsci.2015.07.062
  28. H. D., Park, I. S., Chang, K. J., Lee, "Principles of Membrane Bioreactors for Wastewater Treatment", pp.199-203, CRC Press, 2015.