Journal of Korean Society of Environmental Engineers (대한환경공학회지)

Korean Society of Environmental Engineers (대한환경공학회)
권호 표지

Biosorption Characteristics of Organic Matter in a Sequencing Batch Reactor : Effect of Sludge Retention Time

연속 회분식 반응기내 유기물 생물흡착특성: SRT 영향

  • Kim, Keum-Yong (Department of Environmental Engineering, Chungbuk National University) ;
  • Kim, Jin-Hyung (Department of Environmental Engineering, Chungbuk National University) ;
  • Kim, Dae-Keun (Department of Environmental Engineering, Chungbuk National University) ;
  • Ryu, Hong-Duck (Department of Environmental Engineering, Chungbuk National University) ;
  • Lee, Sang-Ill (Department of Environmental Engineering, Chungbuk National University)
  • 김금용 (충북대학교 공과대학 환경공학과) ;
  • 김진형 (충북대학교 공과대학 환경공학과) ;
  • 김대근 (충북대학교 공과대학 환경공학과) ;
  • 류홍덕 (충북대학교 공과대학 환경공학과) ;
  • 이상일 (충북대학교 공과대학 환경공학과)
  • Published : 2008.02.29
Download PDF
⟨ Previous Next ⟩

Abstract

The objective of this study was to investigate biosorption of organic matter on EPS(Extracellular Polymeric Substances) at different SRT(Sludge Retention Time) in a SBR(Sequencing Batch Reactor) process, which was operated with the following operation steps : Fill-React-Settle-Decant-Idle. The hydraulic retention time was set to be 24 hours. The results obtained from this study showed that the organic removal efficiency per unit microbial biomass decreased with increasing SRT, and the corresponding EPS amount also did. The percent removal of organic by biosorption increased with SRT, and it reached to 53.2% at SRT of 30 days. However, the highest biosorption per microbial biomass(48.6 mgCOD/gVSS) was found at SRT of 2 days. The EPS analysis was performed by measuring TSS, TCOD$_{Cr}$, and TKN. The EPS production per unit microbial biomass was observed to be high at a low SRT. Due to the above result, the floc formation was hindered and therefore poor settlement of sludge resulted in decreasing the COD removal efficiency. It was therefore concluded that the consideration of the system design should include the characteristic of EPS as well as other factors such as SRT, MLSS, and organic loading.

본 연구는 Fill-Contact-Settle-Decant-Idle의 공정으로 구성된 활성슬러지 공정인 SBR(Sequencing bach reactor)공정에서 수리학적 체류시간을 24시간으로 하여 운전하였으며, 세포외 폴리머의 생성량, 흡착량, 제거율 등과 SRT와의 상관관계에 대한 특성을 조사하였다. 본 실험의 목적은 활성슬러지 시스템에서 다양한 SRT를 통한 생물흡착 특성을 결정하기 위한 것이다. 연구 결과 SRT(Sludge retention time)가 증가함에 따라 단위 미생물당 유기물 흡착율 및 제거율이 감소하는 것으로 나타났으며 단위 미생물당 생성되는 세포외 폴리머 양도 감소하는 것으로 나타났다. 생물흡착효율은 SRT가 증가할수록 높았고 SRT 30일에서 그 값은 53.2%였다. 하지만 단위 미생물당 생물흡착량은 SRT 2일에서(48.6 mg COD/gVSS) 가장 높게 관찰되었다. SRT에 따른 EPS량은 TSS, TCOD$_{Cr}$ 그리고 TKN에 의해 정량적으로 분석하였다. 상기의 결과로 인하여 슬러지의 플록 형성을 방해하여 슬러지의 침강성을 저해하며, COD 제거효율을 감소시키는 결과를 초래하는 것으로 사료된다. 따라서 미생물을 이용한 생물학적 공정 운영시 EPS의 특성을 고려하여 SRT, MLSS 유지, 유기물 부하량 등의 설계 인자를 적정히 선정하여 운영하는 것이 필요할 것으로 판단된다.

Keywords

References

  1. Nielsen, P.H., Jahn, A., and Palmgren, R., "Conceptual model for production and composition of exopolymers in biofilms," Water Sci. Technol., 36, 11-19(1997) https://doi.org/10.1016/S0273-1223(97)00318-1
  2. Christensen, B. E., "The role of extracellular polysaccharide biofilms," J. Biotechnol., 10, 181-202(1989) https://doi.org/10.1016/0168-1656(89)90064-3
  3. Lazarova, V., Manem, J., "Biofilm characterization and activity analysis in water and wastewater treatment," Water Res., 29, 2227-2245(1995) https://doi.org/10.1016/0043-1354(95)00054-O
  4. Wingender, J., Neu, T.R., and Flemming, H.C., "What are bacterial extracellular polymeric substnaces?," Microbial Extracellular Polymeric Substances: Characterization, structure and function, Wingender, J., Neu, T.R. and Flemming, H.C.(Ees.), Springer, Berlin, pp. 115(1999)
  5. Evans, E., Brown, M.R.W., and Gilbert, P., "Iron chelator, exopolysaccharide and protease production in Staphylococcus epidermidis: a comparative study of the effects of specific growth rate in biofilm and planktonic culture," Microbiology, 140, 153-157(1994) https://doi.org/10.1099/13500872-140-1-153
  6. Robinson, J. A., Trulear, M. G., and Characklis, W. G., "Cellular reproduction and extracellular polymer formation by Pseudomonas aeruginosa in continuous culture," Biotechnol. Bioeng., 26, 1409-1417(1984) https://doi.org/10.1002/bit.260261203
  7. Turakhia, M. H. and Characklis, W. G., "Activity of Pseudomonas aeruginosa in biofilms : effects of calcium," Biotechnol. Bioeng., 33, 406-414(1988) https://doi.org/10.1002/bit.260330405
  8. Hsleh, K. M., Murgen, G.A., Lion, L.W., and Shuler, M.L., "Interactions of microbial biofilms with toxic trace metals 1. Observation and modeling of cell growth, attachment, and production of extracellular polymer," Biotechnol. Bioeng., 44, 219-231(1994) https://doi.org/10.1002/bit.260440211
  9. APHA, AWWA, WEF, "Standard methods for the examination of water and wastewater," 21th Edition, Edited by Andrew, D. E., Lenore, S. C., Arnold, E.G.(2005)
  10. Ueda, S., Fujita, K., Komatsu, K., and Nakashima, Z., "Polysaccharide produced by genus Pullularia. I, Production of Polysaccharide by growing cells," Appl. Microbiol., 11, 211-215(1963)
  11. Rudd, T., Sterritt, R.M., and Lester, J.N., "Complexation of heavy metals by extracellular polymers in the activated sludge process," J. Water Pollut. Control. Fed, 56, 1260-1268(1984)
  12. Gulas, V., Bond, M., and Benefield, L., "Use of exocellular polymers for thickening and dewatering activated sludge," J. Water Pollut. Control Fed, 51, 798-807(1979)
  13. Pavoni, J. L., Keiber, S. W., and Boblitt, G.T., "The harvesting of algae as a food source from wastewater using natural and induced flocculation techniques," in proceedings of conference on use of wastewater in production of food and fiber, Oklahoma, pp. 435-496(1974)
  14. Paolo, B., Gabriele, F., and Maria, L. R., "Heavy metal shock load in activated sludge uptake and toxic effects," Water Res., 27, 821-827(1993) https://doi.org/10.1016/0043-1354(93)90146-9
  15. Brown, M. J. and Lester, J. N., "Role of bacterial extracellular polymers in metal uptake in pure bacterial culture and activated sludge-I. Effects of metal concentration," Water Res., 16(11), 1539-1548(1982) https://doi.org/10.1016/0043-1354(82)90206-8
  16. Sudhir N. Murthy, "Bioflocculation : Implications for activated sludge properties and wastewater treatment," Ph.D. Thesis, Univerisity of Virginia(1998)