표제지
목차
국문요약
제1장 서론 13
1. 연구배경 13
2. 연구 목적 15
3. 연구 범위 15
제2장 이론적 배경 16
1. 하수슬러지 16
1.1. 하수슬러지의 특징 16
1.2. 하수슬러지의 발생 17
1.3. 하수슬러지 처리현황 18
2. 슬러지 전처리 기술 19
2.1. 국내 하수슬러지 처리의 문제점 19
2.2. 슬러지 전처리기술의 필요성 21
3. Cavitation을 이용한 슬러지 전처리 23
3.1. Cavitation의 원리 23
3.2. Cavitation의 종류 25
3.3. Cavitation의 영향 인자 26
4. CFD를 이용한 가용화 시뮬레이션 27
4.1. 컴퓨터 시뮬레이션 개요 27
4.2. 컴퓨터 시뮬레이션 기법 28
4.3. 지배방정식 30
5. 혐기성 소화 32
5.1. 혐기성 소화의 원리 32
5.2. 혐기성 소화의 영향 인자 36
6. BMP(Biochemical Methane Potential) test 39
제3장 실험 장치 및 방법 41
1. 실험장치 41
1.1. Cavitation에 의한 슬러지 가용화 장치 41
1.2. Pilot-scale 연속식 메탄발효조 46
2. 실험방법 48
2.1. 컴퓨터 시뮬레이션 (CFD) 48
2.2. Cavitation에 의한 슬러지 가용화 53
2.3. BMP test 54
2.4. 가용화된 슬러지를 이용한 메탄발효 59
3. 실험분석 62
제4장 실험결과 63
1. CFD 시뮬레이션 결과 63
2. Cavitation 가용화 결과 75
2.1. Cavitation 단독처리에 따른 가용화 영향 (Run P1) 75
2.2. Ozone과의 병합처리에 따른 가용화 영향(Run P2) 76
2.3. Alkality와의 병합처리에 따른 가용화 영향 (Run P3, Run P4) 78
2.4. 타 연구와의 가용화율 비교 81
3. BMP test를 통한 가용화된 슬러지의 생분해도 평가 84
4. Cavitation에 의해 가용화된 슬러지를 이용한 연속식 메탄발효 89
4.1. Bio-gas 발생량의 변화 91
4.2. 메탄가스 함량의 변화 94
4.3. 유기물 제거에 따른 가스발생량 96
제5장 결론 97
1. 컴퓨터 시뮬레이션 (CFD) 97
2. Cavitation에 의한 가용화 97
3. BMP test를 이용한 생분해도 평가 98
4. 연속식 혐기성 발효조 98
참고문헌 100
ABSTRACT 105
Table 2.1. The Characteristic and solid concentration of each sludge 17
Table 2.2. Status and prospect of sewage sludge product 18
Table 2.3. Annual product and disposal of sewage sludge 19
Table 2.4. Advantage and disadvantage of sludge pretreatment 22
Table 2.5. Influencing factor of cavitation 26
Table 2.6. Optimum and extreme operating conditions of anaerobic digestion 36
Table 3.1. Features of cavitation solubilization device 42
Table 3.2. Specifications of Ozone generator 45
Table 3.3. Calculation conditions of CFD 49
Table 3.4. Set value of VOF 50
Table 3.5. Sludge characteristics of sewage treatment plant 53
Table 3.6. The experimental conditions of cavitation pretreatment 54
Table 3.7. Composition of nutrient medium for BMP test 55
Table 3.8. Characteristics and conditions of sludge for BMP Test 56
Table 3.9. Characteristics of raw and solubilized sludge 59
Table 3.10. Anaerobic sludge composition 60
Table 3.11. Conditions for each anaerobic digestion period 61
Table 3.12. Operating conditions of anaerobic reactor 62
Table 3.13. Analytical methods 62
Table 3.14. Comparison of cumulative bio-gas in BMP test(mL/g VS) 86
Table 3.15. Results of anaerobic fermentation process (HRT=20day) 90
Fig. 2.1. The changes of physical properties during the cavitation process 24
Fig. 2.2. The growth diagram of cavitation bubble 24
Fig. 2.3. Structure of CFX10 28
Fig. 2.4. General CFD structure 29
Fig. 2.5. Process of main-processing 30
Fig. 2.6. Substrate conversion patterns associated with the anaerobic treatment 35
Fig. 2.7. Schematic diagram of BMP test 40
Fig. 3.1. Picture of Cavitation pretreatment device 41
Fig. 3.2. Schematic diagram of experimental set-up for cavitation pretreatment 42
Fig. 3.3. Ozone generator 44
Fig. 3.4. Ozone mixing device 44
Fig. 3.5. Ozone device 44
Fig. 3.6. Schematic diagram of pilot-scale anaerobic tank 47
Fig. 3.7. Modeling and dimensions 48
Fig. 3.8. Boundary condition of cavitation reactor 51
Fig. 3.9. Computational mesh (tetra-prism) 52
Fig. 3.10. Procedure of BMP test 57
Fig. 3.11. Features of pressure under the change in pump flow(20L) 63
Fig. 3.12. Comparison of pressure under the change in pump flow (Inlet P2) 64
Fig. 3.13. Comparison of pressure at each reactor spots in Case 2 65
Fig. 3.14. Features of cavitation index under the change in pump flow (20L) 66
Fig. 3.15. Comparison of cavitation index under the change in pump flow (Inlet P2) 67
Fig. 3.16. Comparison of cavitation index at each reactor spots in Case 2 (Inlet P2) 68
Fig. 3.17. Features of pressure under the change in external circulation pump flow (40L) 69
Fig. 3.18. Comparison of pressure under the change in external circulation pump flow(Inlet P2) 69
Fig. 3.19. Features of cavitation index under the change in external circulation pump flow(40L) 70
Fig. 3.20. Comparison of cavitation index under the change in external circulation pump flow (Inlet P2) 71
Fig. 3.21. Features of pressure under the change in tube diameter (40L) 72
Fig. 3.22. Comparison of pressure under the change in tube diameter (Inlet P2) 72
Fig. 3.23. Features of cavitation index under the change in tube diameter (40L) 73
Fig. 3.24. Comparison of cavitation index under the change in tube diameter (Inlet P2) 74
Fig. 3.25. Variations of SCOD and SS in the cavitational pretreatment 75
Fig. 3.26. Variations of SCOD and SS in the pretreatment under the ozonation 76
Fig. 3.27. Effect of ozone on cavitational pretreatment 77
Fig. 3.28. Variations of SCOD and SS in the pretreatment under the pH 9.5 78
Fig. 3.29. Variations of SCOD and SS in the pretreatment under the pH 12.5 79
Fig. 3.30. Effect of alkality on cavitational pretreatment 80
Fig. 3.31. Effect of ozone and alkality on cavitational pretreatment 81
Fig. 3.32. Comparison of specific SCOD yeilds for sludge solubilization 82
Fig. 3.33. Comparison of energy consumption rates for sludge solubilization 83
Fig. 3.34. Cumulative bio-gas production in BMP test(mL) 84
Fig. 3.35. Effect of solubilized sludge on BMP test (mL/gVS) 85
Fig. 3.36. Effect of solubilized sludge on BMP test(mL/gTS) 87
Fig. 3.37. Variations of methane contents in BMP test 88
Fig. 3.38. Biogas production rate of mesophilic reactor using the raw sludge(R1) 91
Fig. 3.39. Biogas production rate of mesophilic reactor using the solubilized sludge(R2) 91
Fig. 3.40. Biogas production rate of thermophilic reactor using the solubilized sludge(R3) 92
Fig. 3.41. Comparison of biogas production rate 93
Fig. 3.42. Variations of methane contents in mesophilic reactor using the raw sludge(R1) 94
Fig. 3.43. Variations of methane contents in mesophilic reactor using the solubilized sludge(R2) 94
Fig. 3.44. Variations of methane contents in thermophilic reactor using the solubilized sludge(R3) 95
Fig. 3.45. Biogas production by the removal of COD in mesophilic reactor (R2) 96