초록 ▼

Ⅳ. 연구개발결과
본 연구의 제 1세부 개발 결과에서는 거대억새의 저속 열분해 특성 및 활용방안을 도출하였다. 또한, 거대억새와 주요 바이오매스 5종과 특성을 비교분석 하여 거대억새 바이오촤 특성의 우수성을 확인하였다. 저속 열분해를 통해 생성된 바이오촤는 큰 비표면적과 기공 발달등의 장점으로 토양에 활용시 영양분 흡착과 토양질 개량, 온실가스 고정의 효과를 얻을 수 있다. 또한, 수증기를 투입하여 바이오촤를 활성화하면 비표면적이 크게 확대되어 토양질 개선용 비료와 수질 개선용 흡착제로서의 성능 향상이 가능하다. 열분해 생성물

Ⅳ. 연구개발결과
본 연구의 제 1세부 개발 결과에서는 거대억새의 저속 열분해 특성 및 활용방안을 도출하였다. 또한, 거대억새와 주요 바이오매스 5종과 특성을 비교분석 하여 거대억새 바이오촤 특성의 우수성을 확인하였다. 저속 열분해를 통해 생성된 바이오촤는 큰 비표면적과 기공 발달등의 장점으로 토양에 활용시 영양분 흡착과 토양질 개량, 온실가스 고정의 효과를 얻을 수 있다. 또한, 수증기를 투입하여 바이오촤를 활성화하면 비표면적이 크게 확대되어 토양질 개선용 비료와 수질 개선용 흡착제로서의 성능 향상이 가능하다. 열분해 생성물인 바이오오일은 중유와의 혼소를 통해 신재생 연료로 활용하여 온실가스 저감효과를 얻을 수 있다. 또 다른 열분해 부산물인 열분해 가스는 열분해 공정의 열원으로 충분히 활용이 가능하다. 바이오촤 수율 최적화 및 에너지 효율 향상을 위해 외부의 열 공급 없는 소형(수 kg/kr) 바이오촤생산 장치와 열분해 가스 활용을 통해 에너지 효율을 최적화한 상용급(100 kg/hr)의 열분해 공정을 설계하였다.
제 2세부과제에서는 바이오촤를 이용한 중금속 및 유기오염물질 흡착 제거 및 물벼룩(D. magna)을 이용한 생태독성 저감 특성을 확인하였다. 비점오염 수질 개선을 위한 바이오촤 활용 연속 반응기를 제시하였으며, 400℃와 700℃에서 생산된 거대억새 바이오촤를 토양에 5% 수준으로 처리함으로써 토양 미생물의 활성으로 배출되는 CO₂ 배출 저감효과를 평가하였다. 또한, 고농도의 오염 물질이 다수 존재하는 광산 지역 통양의 식물 독성 저감효과를 규명하였다.

Abstract ▼

Background and Research Objectives
Biochar refers to the carbon-rich solid product of pyrolysis from biomass. When applied to the soil, it can sequestrate carbon for a long time without significant biological decomposition due to the stable carbon structure. It can also increase the productivity

Background and Research Objectives
Biochar refers to the carbon-rich solid product of pyrolysis from biomass. When applied to the soil, it can sequestrate carbon for a long time without significant biological decomposition due to the stable carbon structure. It can also increase the productivity of various crops as soil ameliorator. Therefore, biochar production connected with cultivation of energy crops has a potential to become a major technology for mitigation of climate change in rural area. In addition, the biochar has good adsorption characteristics for organic and inorganic pollutants in water or in soil, replacing the use of expensive activated carbon. Therefore, this study investigated the production and characterization of biochar from Geodae Uksae #1 as one of its utilization routes.
Research Scope
This project consisted of two sub-projects. The first sub-project was to produce and characterize the biochar and other byproducts of slow pyrolysis from Geodae Uksae #1. This included the detailed thermo-chemical characterization of biochar, bio-oil and pyrolytic gas and proposal for actual pyrolysis process for technically feasible and economically-viable biochar production.
The second sub-project was to investigate the characterization of the function of biochar in water and soil environment focusing on the pollutant removal and water and soil quality improvement. For biochar studies in water environment, 1) the physiochemical characteristics of biochar in solutions, 2) sorption characteristics of biochars from different pyrolysis temperature, 3) toxicity change by biochar treatment, 4) rapid small scale column test using biochar pellets were conducted. For biochar studies in soil environment, 1) aging test of soil and biochar mixture in incubator, 2) column leaching test of biochar amended heavy metals contaminated soil, 3) phytotoxicity test of eluate of biochar and biochar amended to heavy metals contaminated soil, and 4) soil respiration test of biochar amended heavy metals contaminated soil were conducted.
Research Findings
Using a lab-scale packed bed reactor, pyrolysis products of Geodae-Uksae #1 were produced over a temperature range of 300-700℃ with a heating rate of 10℃/min. A pyrolysis temperature of 500℃ was found appropriate considering the properties of biochar and the heat supplied. The biochar yield was of 27 wt.% at the temperature with a carbon content of 79 wt.% and surface area of 180 m²/g. Large pores of 5-40 μm developed in the biochar, which is beneficial for symbiotic micro-organisms in soil. The bio-oil consisted largely of water, acids and phenols. The energy content in the product gases was sufficient for use as process heat. The biochar were compared to other samples produced from other biomass (umbrella wood, cocopeat, palm kernel shell, rice straw, sugarcane bagasse), and the biochar from Geodae Uksae #1 was found excellent in terms of yield and properties. Based on the results, two pyrolysis processes were proposed: a small scale (several kg/hr) process for domestic biochar production, and a commercial scale (~100 kg/hr) process for biochar and bio-oil production by using the pyrolytic gas as the sole energy input.
In aqueous solution, all biochars from Geodae Uksae #1 greatly increased the solution pH, and the increased amounts were larger at higher pyrolysis temperature. Concentrations of DOC, hardness, dissolved heavy metals in the solutions were within the current water quality guidelines, which allows biochar to become a safe sorbent. The sorption characteristics of biochar were investigated by isotherm and kinetic studies. It was found that the sorption capacity of biochar was larger at higher pyrolysis temperature. The biochar pyrolyzed at 500℃ was found to be the most efficient (BC500) and was used for further studies. Toxicity tests toward Daphnia magna were conducted before and after biochar treatment of aquatic pollutants. The biochar itself was not toxic to the daphnids and reduced the toxicity of pollutant. Moreover, rapid small scale column (RSSC) tests were performed using BC500. It was found that BC500 effectively sorbed heavy metals and organic pollutants. The overall results suggest that biochar produced at 500℃ could be a promising sorbent that is safe and efficient. The results of aging test showed that soil pH increased with the application rate and production temperatures. However, soil EC decreased with production temperatures. In the column leaching test, biochar treatment (5%) is effective at reducing leaching concentration of Cd, Cu, Pb and Zn. But individual pollute adsorption and retention by biochar on a variety contaminated soils is dependent on physico-chemical parameter of soil and biochar. According to the respiration test of soil-biochar mixture, biochar produced at 700oC could adsorb CO₂ generated by the soil microorganism activities. Germination test with biochar eluate and biochar amended contaminated soil showed that biochar reduce phytotoxicity as proved by Lactuca sativa and Raphanus sativus.
Utilization of Research Findings
Since many similar types of biomass are available from agriculture and forestry in rural area, the results of slow pyrolysis acquired for Geodae Uksae #1 and five other biomass provide important information for overall properties of biomass and its utilization for biochar production in future development.
With a large microscopic surface area and good adsorption capability, the biochar can be used to remove organic and heavy metal pollutants in water for improved water quality as an alternative to activated carbon. It can be also applied to remediation of contaminated soil such as in mines, and long-term amelioration of poor quality soil.
Overall, the biochar production via slow pyrolysis can be utilized in rural area for various biomass resources at small-scales, as a major technology for reduction of greenhouse gas. Further development and demonstration are required to find ideal utilization methods of biochar for increased crop productivity and carbon sequestration with various soil and crop types in Korea.

목차 Contents

• 표지 ... 1
• 제출문 ... 2
• 요약문 ... 3
• SUMMARY ... 5
• 목차 ... 8
• 제 1 장 서 론 ... 9
• 제 2 장 국내외 기술개발 현황 ... 12
• 2.1 국내 기술 개발 현황 ... 12
• 2.2 국외 기술 개발 현황 ... 12
• 제 3 장 연구개발 수행 내용 및 결과 ... 14
• 3.1 1세부: 거대억새 바이오촤 생산 및 부산물 활용 기술 개발 ... 14
• 3.1.1 거대억새의 저속 열분해 ... 14
• 3.1.2 거대억새와 바이오매스 5종의 저속 열분해 특성 비교 분석 ... 24
• 3.1.3 바이오촤의 성능 향상(steam activation) ... 33
• 3.1.4 저속 열분해를 상용화 공정 및 에너지 효율 최적화 ... 38
• 3.1.5 결론 ... 47
• 3.2 2세부: 거대억새 바이오촤의 수질 및 토양질 개선 효과 평가 ... 49
• 3.2.1 수환경 및 토양환경에서 바이오촤의 물리화학적 특성 제시 ... 49
• 3.2.2 수환경 및 토양환경에서 바이오촤의 오염물질 저감특성 제시 ... 66
• 3.2.3 수환경 및 토양환경에서 바이오촤의 오염물질 저감특성 제시 ... 85
• 3.2.4 결론 ... 102
• 제 4 장 연구개발 목표 달성도 및 대외 기여도 ... 105
• 4.1 연구 개발 목표 대비 달성도 ... 105
• 4.2 정량적 성과 ... 106
• 제 5 장 연구개발결과의 활용계획 ... 107
• 5.1 활용계획 ... 107
• 5.2 추가연구의 필요성 ... 107
• 5.3 현재추진중인 논문게재 ... 108
• 제 6 장 연구개발과정에서 수집한 해외과학기술정보 ... 109
• 제 7 장 참고문헌 ... 110
• 끝페이지 ... 112