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2025 Vol.35, Issue 4 Preview Page

Special Articles

Effects of Feedstock Mixing Ratios and Inoculum Sources on Anaerobic Digestion of Sewage Sludge and Food Waste

기질 혼합비와 식종원 특성이 하수슬러지와 음식물류폐기물의 혐기성 소화에 미치는 영향 평가

Sungyun Jung1
,
Se Eun Kim1
,
Juhee Shin2
,
Seung Gu Shin3
,
Joonyeob Lee4*
정 성윤1
,
김 세은1
,
신 주희2
,
신 승구3
,
이 준엽4*
1Graduate Student, Major of Environmental Engineering, Division of Earth Environmental System Science, Pukyong National University
2Senior Researcher, Future Convergence Technology Research Institute, Gyeongsang National University
3Professor, Department of Energy System Engineering, Gyeongsang National University
4Professor, Major of Environmental Engineering, Division of Earth Environmental System Science, Pukyong National University
1국립부경대학교 지구환경시스템과학부 환경공학전공 대학원생
2경상국립대학교 미래융복합기술연구소 선임연구원
3경상국립대학교 에너지시스템공학과 교수
4국립부경대학교 지구환경시스템과학부 환경공학전공 교수
*Corresponding Author
31 December 2025. pp. 589-600
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Abstract

We evaluated the effects of feedstock mixing ratios and inoculum sources on the anaerobic digestion of sewage sludge (SL) and food waste (FW) through batch experiments and methanogen community analysis. Both factors influenced methane yield and production rate significantly (p < 0.05). The feedstock mixture ratio had a greater contribution to methane yield variation, and both feedstock mixture ratio and inoculum source affected methane production rates substantially. Co-digestion showed increasing methane yield with higher FW proportions, reaching levels similar to food waste alone at an SL:FW ratio of 25:75 in chemical oxygen demand (COD; 293 ± 11 mL CH4/g COD). Observed methane yields were 13–19% higher than theoretical weighted means, indicating a synergistic co-digestion effect. Methane production rates also increased at ratios of 50:50 and 25:75, reaching values 74–97% higher than sludge alone. Inoculum type strongly affected variability, with co-digester-derived inocula yielding the highest activity and stability. Sequencing demonstrated that these inocula harbored balanced populations of acetoclastic (Methanothrix), hydrogenotrophic (Methanolinea, Methanospirillum), and methylotrophic (Methanofastidiosales) methanogens, enabling robust conversion of diverse intermediates. These results indicate that co-digestion-derived inoculum, combined with FW proportions of >50–75%, may help improve start-up stability and optimize methane productivity in full-scale SL–FW co-digestion systems.

Keywords
co-digestion
mixing ratio
inoculum
sewage sludge
food waste

본 연구에서는 기질 혼합비와 식종원 특성이 하수슬러지와 음식물류폐기물의 혐기성 소화 성능에 미치는 영향을 회분식 혐기성 소화 실험과 메탄생성균 군집 분석을 통해 종합적으로 평가하였다. 기질 혼합 비와 식종원은 모두 메탄 수율과 메탄생성속도에 유의미한 영향을 미치는 요인으로 확인되었으며(p < 0.05), 메탄 수율 변동에는 기질 혼합비의 영향이, 메탄생성속도 변동에는 기질 혼합비와 식종원의 영향이 크게 작용하는 것으로 나타났다. 통합소화 조건에서는 음식물류폐기물 비율이 증가할수록 메탄 수율이 향상되어, 혼합비 25:75 (하수슬러지:음식물류폐기물, COD 기준) 조건에서 음식물류폐기물 단독 조건과 유사한 수준(293 ± 11 mL CH4/g COD)에 도달하였다. 또한 단독소화 기반 이론적 가중 평균값과 비교했을 때, 통합소화의 실제 메탄 수율은 13–19% 더 높아 시너지 효과가 확인되었다. 메탄생성속도 역시 50:50 및 25:75 혼합 조건에서 개선되어 하수슬러지 단독소화 대비 74–97% 높은 값을 나타냈다. 식종원 종류는 메탄생성속도 변동성에 큰 영향을 미쳤으며, 그 중 통합소화조 유래 식종원이 가장 높은 활성 및 안정성을 보였다. 차세대염기서열 분석 결과, 해당 식종원은 아세트산이용성(Methanothrix), 수소이용성(Methanolinea, Methanospirillum), 메틸환원성(Methanofastidiosales) 메탄생성균이 균형 있게 공존하는 군집 구조를 형성하고 있어 다양한 메탄생성 전구체를 안정적으로 메탄으로 전환할 수 있었던 것으로 평가되었다. 통합소화조 유래 식종원과 음식물류폐기물 50–75% 이상의 혼합비를 적용하는 전략은 하수슬러지 및 음식물류폐기물 통합소화 공정에서 스타트업 안정성 확보와 메탄생산성 최적화에 기여할 수 있을 것으로 기대된다.

키워드
통합소화
혼합비
식종원
하수슬러지
음식물류폐기물
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Information
  • Publisher :Korean Society of Engineering Geology
  • Publisher(Ko) :대한지질공학회
  • Journal Title :The Journal of Engineering Geology
  • Journal Title(Ko) :지질공학
  • Volume : 35
  • No :4
  • Pages :589-600
  • Received Date : 2025-12-02
  • Revised Date : 2025-12-19
  • Accepted Date : 2025-12-22
  • DOI :https://doi.org/10.9720/kseg.2025.4.589
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