Clean Technology (청정기술)

The Korean Society of Clean Technology (한국청정기술학회)
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Method of Reducing Separation Membrane Fouling Using Microbubbles

마이크로버블을 이용한 분리막 파울링 저감방법

  • 구경환 (호서대학교 벤처대학원 융합공학과) ;
  • 김영희 (호서대학교 벤처대학원 융합공학과)
  • Received : 2023.01.25
  • Accepted : 2023.03.02
  • Published : 2023.03.31
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Abstract

Due to water shortages caused by water pollution and climate change, total organic carbon (TOC) standards have been implemented for wastewater discharged from public sewage treatment facilities. Furthermore, there is a growing interest and body of research pertaining to the reuse of sewage treatment water as a secure alternative water resource. The membrane bio-reactor (MBR) method is commonly used for advanced wastewater treatment because it can remove organic and inorganic ions and it does not require or emit any chemicals. However, the MBR process uses a separation membrane (MF), which requires frequent film cleaning due to fouling caused by a high concentration of mixed liquor suspended solid (MLSS). In this study, process improvement and microbubble cleaning efficiency were evaluated to improve the differential pressure, water flow, and MF fouling, which are the biggest disadvantages of operating the MF. The existing MBR method was improved by installing a precipitation tank between the air tank and the MBR tank in which raw water was introduced. Microbubbles were injected into a separation membrane tank into which the supernatant water from the precipitation tank was introduced. The microbubble generator was operated with a 15 day on, 15 day off cycle for 5 months to collect discharged water samples (4L) and measure TOC. As the supernatant water from the precipitation tank flowed into the separation membrane tank, about 95% of the supernatant water MLSS was removed so the MF fouling from biological contamination was prevented. Due to the application of microbubbles to supernatant water from the precipitation tank, the differential pressure of the separation membrane tank decreased by 1.6 to 2.3 times and the water flow increased by 1.4 times. Applying microbubbles increased the TOC removal rate by more than 58%. This study showed that separately operating the air tank and the separation membrane tank can reduce fouling, and suggested that applying additional microbubbles could improve the differential pressure, water flow, and fouling to provide a more efficient advanced treatment method.

수자원 오염 그리고 기후변화로 인한 극한의 기상현상으로 물 부족 현상 심화로 공공하수처리 시설의 폐수 배출시 총유기탄 소량(TOC) 기준이 시행되고, 대체 수자원 확보를 위해 하수처리수 재이용에 연구와 관심이 증가하고 있다. 현장에서는 하폐수고도처리로 MBR(membrane bio-reactor)공법을 보편적으로 사용하며, 유기 및 무기 이온 제거 그리고 화학물질의 사용 및 배출이 없다는 친환경적인 장점이 있다. 하지만, 분리막을 사용한 MBR공정은 고농도 활성슬러지 부유물질(mixed liquor suspended solid, MLSS)로 인한 분리막의 막오염(파울링) 현상으로 잦은 막세정 비용 발생의 문제가 있다. 본 연구에서는 분리막 운영시 최대 단점이었던 분리막의 차압 상승, 통수량 저하, 파울링 현상을 개선하고자 i) 공정 개선과 ii) 마이크로버블의 세정 효율을 평가하였다. 기존 MBR공법에 원수가 유입되는 호기조와 MBR조 사이에 침전조를 설치하여 침전조를 거친 상등수가 유입된 분리막조 내부로 마이크로버블을 주입하였다. 마이크로버블은 5개월간 15일 간격으로 마이크로버블 발생장치를 작동(ON), 미작동(OFF)하여 방류수 시료(4L)를 채취 후 TOC를 측정하였다. 침전조를 거친 상등수가 분리막조로 유입하여 원수 MLSS의 95%이상이 제거되어 생물막 등의 오염으로부터 막의 파울링 현상을 1차 방지할 수 있었다. 침전조를 거친 상등수에 마이크로버블의 적용으로 분리막의 차압은 1.6 ~ 2.3배 감소 및 통수량은 최대 1.4배 증가하였다. 마이크로버블의 적용(ON)으로 TOC 제거율은 58% 이상 증가했다. 호기조와 분리막조를 분리 운영함에 따라 침지식 분리막의 파울링 현상을 저감할 수 있고, 추가로 마이크로버블을 적용하여 분리막의 차압, 통수량과 막오염(파울링)이 개선으로 효율적인 고도처리공법을 제시했다.

Keywords

References

  1. '물환경보전법 시행령 및 시행규칙' 국가법령정보센터(www.law.go.kr)
  2. Lee, G.-O. and Park, J.-Y.,"A Case Study on Utilization of Industrial Wastewater Reuse," Journal of the Korean Society of Industry Convergence, 23(1), 17-24 (2020).
  3. Ministry of Environment (MOE) "2021 Statistics of Sewerage," (https://me.go.kr/home/web/index.do?menuId=10264) (accessed Jan. 2023)
  4. Pausta, C. M., Eusebio, R. C., Beltran, A., Huelgas-Orbecido, A., and Promentilla, M. A., "A decision modelling approach for selection of biological nutrient removal systems for wastewater,"In MATEC Web of Conferences, 156, 03013, EDP Sciences (2018)
  5. Lei, S., Zhao, J., Xie, S., Zhao, J., Min, J., Ma, X., and Yan, C., "Comparisons of nitrogen and phosphorus removal efficiency in A2/O process, UCT process, MUCT process, enhanced phosphorus removal process and inverted A2/O process based on GPS-X simulation," In IOP Conference Series: Earth and Environmental Science 983(1), 012114, IOP Publishing (2022, February). https://doi.org/10.1088/1755-1315/983/1/012114
  6. Park, J. H. and Park, H. D., "Advanced biological wastewater treatment," In Current Developments in Biotechnology and Bioengineering, 107-123, Elsevier (2021).
  7. Lee, H. D., Cho, Y. H., and Park, H. B., "Current Research Trends in Water Treatment Membranes Based on Nano Materials and Nano Technologies,"Membrane Journal, 23(2), 101-111 (2013).
  8. Park, Y. H. and Nam, S. Y., "Characterization of Water Treatment Membrane Using Various Hydrophilic Coating Materials," Membrane Journal, 27(1), 60-67 (2017). https://doi.org/10.14579/MEMBRANE_JOURNAL.2017.27.1.60
  9. Cha, B. J. and Kim, H. S., "Introduction of new business: Trends and market outlook in development of membrane technology for water treatment," News & Information for Chemical Engineers, 30(4), 417-420 (2012).
  10. Cha, B. J., Chi, S. D., and Kim, H. S., "Membrane Market for Water Treatment," Korean Industrial Chemistry, 14(6), 2-8 (2011) https://doi.org/10.1016/S0958-2118(11)70128-8
  11. Zuthi, M. F. R., Ngo, H. H., Guo, W. S., Zhang, J., and Liang, S. "A review towards finding a simplified approach for modelling the kinetics of the soluble microbial products (SMP) in an integrated mathematical model of membrane bioreactor (MBR)," Int. Biodeterior. Biodegradation, 85, 466-473 (2013). https://doi.org/10.1016/j.ibiod.2013.03.032
  12. Meng, F., Zhang, S., Oh, Y., Zhou, Z., Shin, H. S., and Chae S. R., "Fouling in membrane bioreactors: An updated review," Water Res., 114, 151-180 (2017). https://doi.org/10.1016/j.watres.2017.02.006
  13. Laabs C. N., Amy G. L., and Jekel M., "Understanding the size and character of fouling-causing substances from effluent organic matter(EfOM) in low-pressure membrane filtration", Environ. Sci. Technol., 40(14), 4495-4499 (2006). https://doi.org/10.1021/es060070r
  14. Chung, G. Y., Kim D. C., and Won I. H., "Method for reducing membrane fouling in the water treatment apparatus,"Patent No. WO2016/068639A1 (2016).
  15. Jung, J., Kim, Y., Nam, H., Kim, Y., Lee, E., Lee, Y., and Kweon, J., "Surface characterization and evaluation of biofouling inhibition of reverse osmosis membranes coated with Epigallocatechin gallate (EGCG)/vanillin," Journal of Korean Society of Water and Wastewater, 28(6), 713-723 (2014). https://doi.org/10.11001/jksww.2014.28.6.713
  16. Saratale, G. D., Saratale, R. G., Shahid, M. K., Zhen, G., Kumar, G., Shin, H. S., Choi, Y. G., and Kim, S. H., "A comprehensive overview on electro-active biofilms, role of exo-electrogens and their microbial niches in microbial fuel cells (MFCs)," Chemosphere, 178, 534-547 (2017). https://doi.org/10.1016/j.chemosphere.2017.03.066
  17. Hung, Y. C., Waters, B. W., Yemmireddy, V. K., and Huang, C. H., "pH effect on the formation of THM and HAA disinfection byproducts and potential control strategies for food processing," J. Integr. Agric., 16(12), 2914-2923 (2017). https://doi.org/10.1016/S2095-3119(17)61798-2
  18. Gukelberger, E., Gabriele, B., Hoinkis, J., and Figoli, A. "MBR and integration with renewable energy toward suitable autonomous wastewater treatment," In Current Trends and Future Developments on (Bio-) Membranes, 355-384. Elsevier (2019).
  19. Xu, H. and Lui, Y., "D-Amino acid mitigated membrane biofouling and promoted biofilm detachment," J. Memb. Sci., 376, 266-274 (2011). https://doi.org/10.1016/j.memsci.2011.04.030
  20. Le Clech, P., Jefferson, B., Chang, I. S., and Judd, S. J., "Critical flux determination by the flux-step method in a submerged membrane bioreactor,"J. Memb Sci., 227(1-2), 81-93 (2003). https://doi.org/10.1016/j.memsci.2003.07.021
  21. Lee, C.-H., Kim, G.-Y., Kim, H.-S., Kim, J.-H., and Lee, K.-I., "Applicability evaluation of microbubble for membrane fouling reduction in wastewater reuse membrane process,"Journal of the Korean Society of Water and Wastewater, 31(2), 169-175 (2017). https://doi.org/10.11001/jksww.2017.31.2.169
  22. Nam, G. W. and Jung, J. H., "Application of Ozone Microbubbles in the Field of Water and Wastewater Treatment," Ecology and Resilient Infrastructure, 3(4), 256-262, (2016). https://doi.org/10.17820/ERI.2016.3.4.256
  23. Jang, J. K., Jin, Y. J., Kang, S. W., Kim, T. Y., Paek, Y., Sung, J. H., and Kim, Y. H., "Simultaneous Removal of Organic Pollutants, Nitrogen, and Phosphorus from Livestock Wastewater by Microbubble-Oxygen in a Single Reactor," J. Korean Soc. Environ. Eng., 39(11), 599-606 (2017). https://doi.org/10.4491/KSEE.2017.39.11.599
  24. Song, D. H., Kang, J. H., Park, H. S., Song, H. J., and Chung, Y. G. "Simultaneous Removal of NO and SO2 using Microbubble and Reducing Agent," Clean Technol., 27(4), 341-349 (2021).
  25. Kim, G.-R. "Water Purification by Microbubble - Case of Domestic Application," Korea Fisheries Infrastructure Promotion Association, 103, 37-42 (2013).
  26. Hong, S.-H., Lee, K.-H., and Jeong, N.-W., "Development of Oil Flushing System with Microbubble Generator," Tribol. Lubr., 38(3), 109-114 (2022).
  27. Cha, H. S., "Present State and Future Prospect for Microbubble Technology," Bull. Food Technol., 22(3), 544-552 (2009).
  28. Agarwal, A., Ng, W. J., and Liu, Y., "Principle and applications of microbubble and nanobubble technology for water treatment," Chemosphere, 84(9) 1175-1180 (2011). https://doi.org/10.1016/j.chemosphere.2011.05.054
  29. Marui, T., "An Introduction to Micro/Nano-Bubbles and Their Applications," Systemics, Cybernetics and Informatics, 11(4), 68-73 (2013).
  30. Kyllonen, H. M., Pirkonen, P., and Nystrom, M., "Membrane iltration enhanced by ultrasound: a review," Desalination, 181, 319-335 (2005). https://doi.org/10.1016/j.desal.2005.06.003
  31. Li, P., Takahashi, M., and Chiba, K., "Enhanced Free-Radical Generation by Shrinking Microbubbles Using a Copper Catalyst," Chemosphere, 77, 1157-1160 (2009). https://doi.org/10.1016/j.chemosphere.2009.07.062
  32. Radha, K. V., and Sirisha, K., "Chapter 11: Electrochemical oxidation processes. In Advanced oxidation processes for waste water treatment," Academic Press. 359-373 (2018).
  33. Ku, K.-H., "Separation membrane water treatment apparatus using microbubble," Patent No. 10-2019-0033317 (2017)
  34. Zhou, Z. A., Xu. Z., Finch, J. A., Masliyah, J. H., and Chow, R.S., "On the role of cavitation in particle collection in flotation - A critical review. II," Miner. Eng., 22(5), 419-433 (2009). https://doi.org/10.1016/j.mineng.2008.12.010