DOI QR코드

DOI QR Code

Effects of Adsorption and Decomposition on the Removal of Total Organic Carbon (TOC) in Oil Wastewater by Cellulose-based Pseudo Graphene and Persulfate

셀룰로오스 기반 유사-그래핀과 과황산염에 의한 압연류 폐수내 총유기탄소(TOC) 흡착 및 분해효과 연구

  • Song-I Kim (Department of Environmental Engineering, Kwangwoon University) ;
  • Ji-Young Shin (Department of Environmental Engineering, Kwangwoon University) ;
  • Kyung-Chul Park (Department of Environmental Engineering, Kwangwoon University) ;
  • Jae-Kyu Yang (Department of Environmental Engineering, Kwangwoon University) ;
  • Dong-Su Kim (Department of Environmental Engineering, Kwangwoon University)
  • 김송이 (광운대학교 환경공학과) ;
  • 신지영 (광운대학교 환경공학과) ;
  • 박경철 (광운대학교 환경공학과) ;
  • 양재규 (광운대학교 환경공학과) ;
  • 김동수 (광운대학교 환경공학과)
  • Received : 2024.03.18
  • Accepted : 2024.08.09
  • Published : 2024.09.30

Abstract

Chemical oxygen demand (COD), an organic material measurement index, has a limit to the management of the total amount of all organic materials including non-degradable organic materials due to low oxidation rate. So total organic carbon (TOC) that can measure organic materials more accurately is introduced and used as a measurement index. Several environmental companies including company A in Gyeonggi-do dilute raw wastewater first and then treats it with chemicals. And an activated carbon is used at the rear stage to treat total organic carbon even though various treatment processes can be applied to reduce TOC in wastewater. There are some problems such as use of a lot of diluting water and generation of an excessive amount of sludge, so it is urgent to come up with an alternative plan. Therefore, in this study, an application experiment was conducted on two different methods for improving the TOC reduction efficiency of waste water from Company A. The first method is the evaluation of the substitution potential of powered activated carbon(PAC), an adsorbent currently used, by manufacturing cellulose-based graphene like carbon (CGLC). This first study showed that CGLC had about 10% higher TOC adsorption efficiency than commercial PAC, showing the possibility of being applied as an alternative adsorbent for PAC in water treatment sites. The second method relates to the removal of TOC by sulfate radials produced by persulfate (PS) activation. Two activation methods were applied: using CGLC and PAC as carbon-based catalyst and using the high temperature of wastewater for PS activation. As a result of using PAC and CGLC as PS activation materials, the TOC removal rate was lower than the adsorption amount of TOC by CGLC and PAC due to excessive chlorine ions present in the real wastewater. However, as a result of using the high water temperature (55~60℃) of the field wastewater for PS activation, it showed a much greater TOC removal efficiency than PAC alone, CGLC alone, and using a carbon-based catalyst for PS activation. When PS was injected more than 0.5%, it showed a TOC removal efficiency of 95% or more within 24 hr. In addition, when PS was injected more than 0.3%, the TOC concentration could be lowered to less than 75 ppm, which is the wastewater discharge standard applied to company A. When these results were summarized, raw wastewater of high temperature can be treated with a simple process of only adding of PS and discharged by treating TOC below the wastewater discharge standard applied to company A.

유기물 측정지표인 화학적산소요구량(COD)은 산화율이 낮아 난분해성 유기물까지 포함한 전체 유기물질의 총량관리에 한계를 가지고 있어 보다 정확한 측정이 가능한 총유기탄소(TOC)가 측정지표로 도입되어 사용되고 있다. 폐수 내 TOC 저감을 위해서는 여러 공정들이 적용가능하나 경기도 소재의 A사를 비롯한 여러 환경업체에서는 원폐수를 먼저 희석한 후 약품처리에 의한 응집침전과정을 거치고 후단에 활성탄을 사용하여 총유기탄소를 처리하고 있는 실정이다. 현장에서는 많은 물 사용과 약품사용으로 인한 슬러지가 과다하게 발생하는 문제가 있어 이를 대체할 수 있는 방안도출이 시급한 실정이다. 따라서 본 연구에서는 A사 실폐수의 TOC 저감효율 증진을 위해 두 가지 다른 방법을 적용하였다. 첫 번째 방법은 셀룰로오스 기반 유사-그래핀(CGLC)을 제조하여 현재 사용되고 있는 흡착제인 분말활성탄(PAC)의 대체가능성 평가에 관한 것이다. 첫 번째 연구를 통해서는 CGLC가 상업용 PAC보다 TOC 제거율에서 약 10% 정도의 높은 성능을 보여 수처리 현장에서 PAC의 대체 흡착제로 적용될 수 있는 가능성을 보여주었다. 두 번째 방법은 persulfate(PS) 활성화에 의해 생성되는 황산라디칼에 의한 TOC 제거에 관한 것이다. PS 활성화를 위해 CGLC와 PAC을 사용하는 것과 폐수의 높은 온도를 이용하는 두 가지 방법을 적용하였다. PAC과 CGLC를 PS 활성화물질로 사용한 결과, TOC 제거율은 실폐수내 존재하는 과량의 염소이온에 의해 CGLC와 PAC에 의한 TOC의 흡착제거량 보다 낮게 나타났다. 그렇지만 PS 활성화를 위해 현장 폐수의 높은 수온(55~60℃)을 이용한 결과 PAC 단독, CGLC 단독 그리고 PS 활성화에 탄소계 매질을 사용한 것보다 훨씬 큰 TOC 제거능을 보였으며, PS를 0.5% 이상 주입시 24 시간 이내에 95% 이상의 TOC 제거능을 보였다. 또한 PS를 0.3% 이상 주입시 A사의 폐수 배출기준인 75 ppm 이하로 TOC 농도를 낮출 수 있었다. 이러한 결과를 종합하면, 높은 온도의 원폐수에 PS만 첨가하는 간편한 공정으로도 TOC를 A사의 폐수 방류기준 이하로 처리하여 배출할 수 있는 것으로 나타났다.

Keywords

Acknowledgement

이 논문은 과학기술정보통신부 한국연구재단(RS-2023-00237769) 재원의 일부 지원을 받아 수행되었으며, 서울녹색환경지원센터(SGEC) 연구개발사업의 일환으로 일부 지원받아 수행하였습니다.

References

  1. Ministry of Environment, Guidance on switching organic material metrics (COD to TOC), http://me.go.kr/home/web/main.do (Accession date: February 17, 2024)
  2. Kong, X., Zhu, Y., Lei, H., Wang, C., Zhao, Y., Huo, E., Lin, X., Zhang, Q., Qian, M., Mateo, W., Zou, R., Fang, Z., and Ruan, R., "Synthesis of graphene-like carbon from biomass pyrolysis and its applications", Chemical Engineering Journal, 399, pp. 125808. (2020).
  3. Kim, S. H., "Adsorptive removal of cationic and anionic dyes using cellulose-derived graphene- like carbon (CGLC)", Kwangwoon University, pp. 5~29. (2021).
  4. Guerra-Rodriguez, S., Rodriguez, E., Devendra, N. S., and Rodriguez-Chueca, J., "Assessment of Sulfate Raical-Based Advanced Oxidation Processes for Water and Wastewater Treatment: A Review", Water, 10(12), pp. 1828 (2018).
  5. Gao, Y., Wang, Q., Ji, G., and Li, A,, "Degradation of antibiotic pollutants by persulfate activated with various carbon materials", Chemical Engineering Journal, 429, pp. 1~3. (2022).
  6. Xia, X., Zhu, F., Li, J., Yang, H., Wei, L., Li, Q., Jiang, J., Zhang, G., and Zhao, Q., "A Review Study on Sulfate-Radical-Based Advanced Oxidation Processes for Domestic/Industrial Wastewater Treatment: Degradation, Efficiency, ang Mechanism", Front Chem., 8 (2020)
  7. Ho, Y. S., and Mckay, G., "Pseudo-second order model for sorption processes", Process Biochemistry, 34(5), pp. 451~465. (1999).
  8. Simonin, J.-P., "On the comparison of pseudo-first order and pseudo-second order rate laws in the modeling of adsorption kinetics", Chemical Engineering Journal, 300, pp. 254~263. (2016).
  9. [오희소, 장재수, "MgCl2전처리를 이용한 표면개질을 통한 바이오차의 Congo red 흡착성능 향상", 대한환경공학회지, 42(10), 472~481] Oh, H. S., and Chang, J. S.,"Enhancement of the Congo Red Adsorption Capacity of Biochars by Surface Modification with MgCl2 Pretreatment", Journal of the Korean Society of Environmental Engineers, 42(10), pp. 472~481. (2020).
  10. Zhong, Z., Yu, G., Mo, W., Zhang, C., Huang, H., Li, S., Gao, M., Lu, X., Zhang, B., and Zhu, H., "Enhanced phosphate sequestration by Fe(III) modified biochar derived from coconut shell", RSC Advances, 9(18), pp. 10425~10436. (2019).
  11. Kim, Y.-S., and Kim, J.-H., "Isotherm, kinetic and thermodynamic studies on the adsorption of paclitaxel onto Sylopute", The Journal of Chemical Thermodynamics, 130, pp. 104~113. (2019).
  12. Singh, T. S., and Pant, K. K., "Equilibrium, kinetics and thermodynamic studies for adsorption of As(III) on activated alumina", Separation and Purification Technology, 36(2), pp. 139~147. (2004).
  13. Yuan, G., Qing, W., Guozhao, J., and Aimin, L., "Degradation of antibiotics pollutants by persulfate activated with various carbon materials", Chemical Engineering Journal, 429, 132387. (2022).
  14. Ministry of Environment. "Regulations on the Enforcement of the Water Environment Conservation Act." [Effective April 17, 2023; Ministry of Environment Ordinance No. 1032.] [April 17, 2023; Amendments from Other Laws] Appendix 13.