응집침전, 부상분리 및 펜톤산화를 이용한 축산폐수 전처리 연구

다국어 초록 (Multilingual Abstract)

Livestock wastewater which contains excrement and urine of livestock and washing water has not only high density and viscosity but also particulate solid materials. To achieve high removal efficiency in a biological treatment process for this wastewater, it is necessary to separate solid materials from liquid wastewater in the pretreatment process.
In this study, pretreatment system for solid-liquid separation and optimum operation conditions of each pretreatment system was searched by investigating the characteristics of livestock wastewater generated from G city of Gyeongnam and pretreatment system of public livestock wastewater treatment plants in Korea.
The livestock wastewater amounts generated from G city were 2,733 m3/d and 89% of them were from pigs. This wastewater contained high level of dissolved and persistent organic matter such as VSS/SS 74%, SCODCr/TCODCr 74%, and CODMn/TCODCr 22%.
And the most of public livestock wastewater treatment facilities had composed of total impurities remover and centrifugal separator system, but had not kept constant removal efficiency. To improve biological treatment efficiency, three stages of pretreatment system has been recommended as : total impurities remover to remove impurities for first stage, centrifugal separator for solid-liquid separation for second stage, and coagulation, flotation, and Fenton oxidation for the third stage.
In this study, the optimum operational conditions were investigated for the third stage solid-liquid separation such as coagulation, flotation, and Fenton oxidation by using laboratory scale batch experiment and continuous pilot plant research.
The results were summarized as follows ;
1. Coagulation precipitation efficiency had the following order ; FeCl3 (1000mg/L)> PAC(1500mg/L) > Alum(1500mg/L) for their optimum dosing amount. In case of polymer coagulant, only cationic polymer coagulant had an effect on coagulation with 200 mg/L of optimum dosage amount. Combined coagulant mixed with inorganic and cationic polymer coagulants showed the highest removal efficiency. The optimum combined coagulant amounts were 500 mg/L of inorganic coagulant and 25 mg/L of cationic polymer coagulant.
2. The optimum operational conditions for flotation using DAF were 400% of recycle ratio, 4 atm and pH 4. In addition to 500 mg/L of Alum, 50 mg/L of cationic polymer coagulant had proper operational condition for the flotation followed by coagulation with combined coagulants.
3. Fenton oxidation to achieve removal of persistent organic materials and separation of solid-liquid had the optimum efficiency at the condition of initial pH 4, 10:1 of H2O2/Fe2+ dosing rate, 5,000/500 mg/L of H2O2/Fe2+ dosing amount, and Ca(OH)2 as counteragent.
4. As results from laboratory experiments, the removal efficiency of SS and CODCr were 79% and 50% for coagulation-precipitation, 87% and 61% for flotation, and 84% and 43% for Fenton oxidation, respectively. Flotation showed the highest efficiency but all of these three processes might be applied for the pretreatment of livestock wastewater as solid-liquid separation.
5. In the pilot plant research using Fenton oxidation, the removal efficiency of BOD and COD was about 50%. TS increased after Fenton oxidation due to the addition of chemicals. Sulfate ion causing the increase of TS seems to have disadvantage for degradation of organic matter because of low ratio of COD/SO42-. On the other hand, ferric ion might not have adverse effect on the next step anaerobic biological process by making precipitation from reaction of iron reducing bacteria and other iron oxides and improving activation of anaerobic microorganism.

목차 (Table of Contents)

• I. 서론 1
• 1. 연구배경 및 목적 1
• 2. 연구내용 및 범위 4
• Ⅱ. 축산폐수의 일반적 현황 7
• 1. 축산현황 및 축산폐수 발생현황 7
• 1) 축산현황 7
• 2) 축산폐수 발생량 13
• 2. 축산분뇨의 성상 및 특성 15
• 3. 돈사형태별 특성 19
• 4. 축산농가의 방지시설 및 축산폐수공공처리시설 현황 21
• Ⅲ. 축산폐수 전처리 공정 도출 24
• 1. 경남 G시의 축산농가 현황 및 폐수발생량 24
• 1) 축산농가 현황 및 폐수발생량 24
• 2) 경남 G시의 축산폐수 특성 25
• 2. 고액분리 장치별 특성 38
• 1) Screen 38
• 2) Vacuum Filtration 40
• 3) Belt Press 41
• 4) Filter Press 41
• 5) Screw Press 42
• 6) 원심분리기 42
• 3. 축산폐수 전처리 시스템 도출 44
• 4. 결론 47
• Ⅳ. 응집침전을 이용한 축산폐수 전처리 48
• 1. 이론적 배경 48
• 1) 응집침전의 개요 48
• 2) 응집이론 48
• 3) 응집제의 종류 및 특성 54
• 4) 응집에 의한 인 제거 63
• 2. 실험재료 및 실험방법 64
• 1) 실험재료 64
• 2) 실험방법 64
• 3. 결과 및 고찰 66
• 1) 무기성 응집제를 이용한 응집침전 66
• 2) 고분자 응집제를 이용한 응집침전 73
• 3) 무기성 응집제와 고분자 응집제를 혼합 적용한 응집침전 77
• 4. 결론 83
• Ⅴ. 부상분리을 이용한 축산폐수 전처리 84
• 1. 이론적 배경 84
• 1) 부상분리의 개요 84
• 2) 부상분리의 분류 84
• 3) 용존공기부상분리(DAF)의 원리 86
• 4) 용존공기부상분리의 처리효율에 영향을 미치는 인자 90
• 2. 실험방법 및 실험장치 94
• 1) 실험재료 94
• 2) 실험방법 94
• 3) 실험장치 95
• 3. 결과 및 고찰 97
• 1) 부상분리(DAF) 운전을 위한 적정 운전조건 97
• 2) pH를 조정한 축산폐수에 대한 부상분리 107
• 3) 무기성 응집제와 양이온성 고분자 응집제 혼합적용에 따른 부상분리 110
• 4. 결론 113
• Ⅵ. 펜톤산화를 이용한 축산폐수 전처리 114
• 1. 이론적 배경 114
• 1) 고급산화공정 114
• 2) 고급산화공정의 분류 116
• 3) 펜톤산화의 반응 메카니즘 118
• 4) 펜톤산화의 주요 영향인자 123
• 2. 실험재료 및 실험방법 129
• 1) 실험재료 129
• 2) 실험방법 130
• 3. 결과 및 고찰 132
• 1) pH에 따른 영향 132
• 2) H2O2/Fe2+의 적정 주입비 138
• 3) H2O2/Fe2+의 적정 주입량 144
• 4) 펜톤산화 후 중화 150
• 4. 응집침전, 부상분리 및 펜톤산화 공정 비교 155
• 5. 결론 157
• Ⅶ. 펜톤산화 공정의 pilot plant를 이용한 축산폐수 전처리 159
• 1. 실험장치 및 실험방법 159
• 1) 실험장치 159
• 2) 실험방법 166
• 2. 결과 및 고찰 168
• 1) TBOD와 SBOD의 농도변화 168
• 2) TCODCr와 SCODCr의 농도변화 170
• 3) 생분해도 172
• 4) T-N과 NH4-N의 농도변화 174
• 5) T-P의 농도변화 176
• 6) pH와 Alkalinity의 농도변화 177
• 7) SS와 VSS의 농도변화 178
• 8) TS와 VS의 농도변화 179
• 3. 결론 185
• Ⅷ. 종합결론 186
• 참고문헌 189