Journal of Korean Society of Environmental Engineers (대한환경공학회지)

Korean Society of Environmental Engineers (대한환경공학회)
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High-Rate Phosphorous Removal by PAC (Poly Aluminum Chloride) Coagulation of A2O Effluent

생물공정 처리수의 PAC (Poly Aluminum Chloride) 응집에 의한 고효율 인 제거 특성

  • Hwang, Eung-Ju (Department of Environmental Engineering, Daegu University) ;
  • Cheon, Hyo-Chang (Department of Environmental Engineering, Daegu University)
  • 황응주 (대구대학교 환경공학과) ;
  • 천효창 (대구대학교 환경공학과)
  • Received : 2009.05.18
  • Accepted : 2009.08.14
  • Published : 2009.08.31
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Abstract

High-rate phosphorous removal by PAC (poly aluminum chloride) coagulation of A2O effluent was investigate to meet the stringent requirement of wastewater discharge from municipal wastewater treatment plant. A series of jar tests were conducted to find optimum coagulation condition and to enhance removal efficiency. The optimum volumetric concentration of PAC was 30 ppm (2.81mol Al/mol P by mol ratio). Only 17.2% of soluble P was removed for 30 minutes' settling without PAC addition, while this increased to 30.3% by dosing 10ppm PAC. It even increased conspicuously from 49.3% to 88.4% by increasing PAC dose from 20 ppm to 30 ppm. 92.4% of total P was removed by 30 ppm PAC, and the effluent concentration (0.3 mg/L) was acceptable for discharge. The optimum value of coagulation time, settling time, and pH were 4minutes, 20 minutes, and 7.0, respectively. It was not necessary to control pH of raw sample whose pH was 7.0. Soluble P removal was remarkably enhanced at pH 7.0. This implied that sweep floc formation by $Al(OH)_3$ was the main mechanism of coagulation for soluble P removal. Influent and effluent of secondary clarifier were tested for coagulation, and the effluent was better for high-rate P removal. It resulted in 0.18 mg/L of P and 95.4% of P removal by coagulation. It was favorable to recycle the treated water to coagulation tank and the optimum recycle ratio was 0.3.

2011년부터 시행될 2단계 수질 오염 총량제에 대비하여 고효율 인 제거 공정 개발이 필요하며 본 연구에서는 생물학적 처리와 화학적 응집처리를 조합한 공정이 대안으로 검토되었다. 2세대 응집제로서 최근 많이 사용되고 있는 PAC(poly aluminum chloride)를 이용하고 실제 하수종말처리장 A2O 공정의 호기조 유출수를 시료로 하여 인 응집 특성 및 적정 조건, 효율 향상 방안 등에 대해 실험연구를 수행하였다. 먼저 적정 PAC 투입 농도는 부피기준으로 30 ppm, mol비로는 2.81 mol Al/mol P인 것으로 나타났다. 단순침전에서 17.2%에 불과하던 용존성 인의 제거율이 PAC 10 ppm 투입으로 30.3%까지 증가하였으며, 20 ppm에서 30 ppm으로 PAC 투입량을 증가시킬 때 49.3%에서 88.4%로 제거율을 크게 향상시킬 수 있었다. 이때 총 인의 제거율은 92.4%, 유출수 총 인 농도는 0.3 mg/L로 총량제에 부합하는 방류수 수질을 달성할 수 있었다. 적정한 응집시간은 4분, 침전시간은 20분, 초기 pH는 7로 나타났고 원시료 (pH 7.0)는 별도의 pH 조절 없이 응집 가능한 것으로 판단되었다. pH 7 조건에서 용존성 인의 제거가 크게 향상되었으며, 추가적인 확인 연구가 필요하나, 이는 인의 경우 $Al(OH)_3$에 의한 sweep floc formation이 주요 제거 기작임을 의미하였다. 2차침전조 유입부에 PAC를 투입하여 2차침전조를 응집침전조로 활용하는 방안과 별도의 응집침전조를 2차침전조 후단에 설치하여 PAC를 투입하는 방안을 비교한 결과 PAC 투입량 대비 인 제거효율 증진 관점에서 후자가 바람직한 것으로 조사되었다. 이때 처리수의 인 농도는 0.18 mg/L, 제거율은 95.4%로 향상시킬 수 있었다. 끝으로 응집 처리수를 반송할 경우 인 제거 효율을 높일 수 있었으며 적정 반송율은 0.3인 것으로 분석되었다.

Keywords

References

  1. 국립환경과학원, 낙동강수계 제2단계 수질오염총량관리 광역시도 경계점 목표수질(안), (2007)
  2. 대구환경시설공단, 수질오염총량제 실시에 대처할 고효율 총인처리기술 개발, (2009)
  3. 宮功, 津野洋, 水環境基礎科學, コロナ一社, 143(1997)
  4. 栗原淳, 越野正義, 肥料製造學, 養賢堂, 95-96(1986)
  5. Rittmann, B.E., and McCarty, P.L., Environmental Biotechnology, McGraw-Hill Korea(한역판), 579-590(2002)
  6. 김미향, 김영만, 최범석, '알루미늄 응집제들에 의한 몇가지 유기화합물의 응집효과에 관한 연구', Anal. Sci. & Technol., 12(6), 478-483(1999)
  7. Gao, B.Y., Yue, Q.Y., Wang, B.J., and Chu, Y.B., 'Polyaluminum- silicate-chloride (PASiC)-a new type of composite inorganic polymer coagulant', Colloids Surf., A: Physicochemical Engineering Aspects, 229(1-3), 121-127(2003) https://doi.org/10.1016/j.colsurfa.2003.07.005
  8. Gao, B. Y,. and Yue, Q. Y.,' $Effect of SO4^{2-}/Al^{3 +}$ ratio and $OH^-/Al^{3+}$ value on the characterization of coagulant poly-aluminumchloride- sulfate (PACS) and its coagulation performance in water treatment', Chemosphere, 61(4), 579-584(2005) https://doi.org/10.1016/j.chemosphere.2005.03.013
  9. Ghafari, S., Aziz, H. A., Isa, M. H., and Zinatizadeh, A. A.,'Application of response surface methodology (RSM) to optimize coagulation?flocculation treatment of leachate using poly-aluminum chloride (PAC) and alum', Journal of Hazardous Materials, 163(2-3), 650-656(2008) https://doi.org/10.1016/j.jhazmat.2008.07.090
  10. Jiang, J. Q., and Graham, N. J. D.,' Development of optimal poly-alumino-iron sulphate coagulant', J. Environ. Engineering, 129(8), 699-708(2003) https://doi.org/10.1061/(ASCE)0733-9372(2003)129:8(699)
  11. Gao, B. Y., Hahn, H. H., and Hoffmann, E., 'Evaluation of aluminum-silicate polymer composite as a coagulant for water treatment', Water Res., 36(14), 3573-3581(2002) https://doi.org/10.1016/S0043-1354(02)00054-4
  12. Kwak, J. W., and Gillberg, L., 'Influence of pH and coagulant basicity in precipitating orthophosphate by Al/Fe salts', 한국수질보전학회지, 13(1), 25-34(1997)
  13. Sinha, S., Yoon, Y., Amy, G., and Yoon, J., 'Determining the effectiveness of conventional and alternative coagulants through effective characterization schemes', Chemosphere, 57(9), 1115-1122(2004) https://doi.org/10.1016/j.chemosphere.2004.08.012
  14. Ntampou, X., Zouboulis, A. I., and Samaras, P., 'Appropriate combination of physico-chemical methods (coagulation/ flocculation and ozonation) for the efficient treatment of landfill leachates', Chemosphere, 62(5), 722-730(2006) https://doi.org/10.1016/j.chemosphere.2005.04.067
  15. Zhang. C., and Wang, Y.', Removal of dissolved organic matter and phthalic acid esters from landfill leachate through a complexationflocculation process', Waste Management, 29(1), 110-116(2009) https://doi.org/10.1016/j.wasman.2008.02.023
  16. Duan, J., and Gregory, J.', Coagulation by hydrolyzing metal salts', Advances in Colloid Interface Science, 100-102, 475-502(2003) https://doi.org/10.1016/S0001-8686(02)00067-2
  17. Gray, K. A., Yao, C., and O’Melia, C.R., 'Inorganic metal polymers: preparation and characterization', J. American Water Works Association, 87(4), 136-146(1995) https://doi.org/10.1002/j.1551-8833.1995.tb06350.x
  18. Rebhun, M., and Lurie, M., 'Control of organic matter by coagulation and flocs separation', Water Sci. Technol., 27, 1-20(1993) https://doi.org/10.1021/es00038a700
  19. Dentel, S. K., and Gosset, J. M., 'Mechanisms of coagulation with aluminum salts', J. Am. Water Works Assoc., 80(4), 187-198(1988) https://doi.org/10.1002/j.1551-8833.1988.tb03025.x
  20. Srivastava, V. C., Mall, I. D., and Mishra, I. M., 'Treatment of pulp and paper mill wastewaters with poly aluminum chloride and bagasse fly ash', Colloids and Surfaces A: Physicochemical Engineering Aspects, 260(1-3), 17-28(2005) https://doi.org/10.1016/j.colsurfa.2005.02.027
  21. Hundt, T. R., and O’Melia, C. R., 'Aluminum-fulvic acid interactions: mechanisms and applications', J. Am. Water Works Assoc., 80(4), 176-186(1988) https://doi.org/10.1002/j.1551-8833.1988.tb03023.x
  22. Clark, M. M., and Srivastava, R. M., 'Mixing and aluminum precipitation', Environ. Sci. Technol., 27(10), 2181-2189 (1993) https://doi.org/10.1021/es00047a027
  23. 우승순, 이찬기, 김성석, 최규열, 이해금, '춘천시 하수처리장 의 처리공정에서 인의 거동과 존재형태', 한국수질보전학회지, 9(2), 98-104(1993)