고흡착 골탄을 이용한 불소 제거용 수처리 시스템의 최적 운전 조건

국문 초록 (Abstract)

목적: 에티오피아에서는 지하수 불소 제거를 위해서 골탄을 이용하고 있지만, 흡착 효율이 낮아 잦은 교체비용의 부담을 안고 있다. 또한, 처리수에 탁도와 유기물이 함유되어 식수의 안전성이 떨어진다. 이에 본 연구에서는 현지에서 생산 가능한 고흡착 골탄을 개발하였으며 초기 탁도 및 유기물 저감을 위한 최적의 운전조건을 도출하였다.
방법: 뼈를 씻어 건조시킨 후 내부까지 태워질 수 있도록 절단하여 전기로에서 350, 450, 550℃에서 온도별로 1, 3, 5시간을 태워 골탄을 제작하였다. 태워진 골탄들은 에티오피아 현지에서 운영되는 골탄 크기인 600~2,000 ㎛로 분쇄하여 실험하였다. SEM과 BET를 이용해 골탄 표면 분석을 수행하였으며, 회분기 실험를 통해 kinetic, isotherm 흡착 실험을 하였다. 컬럼실험은 초기 불소 농도 4.8 ㎎/L에서 100, 200, 300, 400 L/day의 유속 조건으로 90분 운전하면서 탁도, TOC, 불소 농도 변화를 확인하였다.
결과 및 토의 : 최적의 골탄 제조 조건으로 450℃에서 3시간 태우는 것이 탁도와 유기물 제거 측면에서 효과적이었다. SEM, BET 분석을 통해서 골탄의 표면 거칠기와 비표면적 특징이 불소 흡착효율에 영향을 미쳤다. 회분기 실험을 통해서 제조된 골탄의 흡착능이 3.7 ㎎ F/g으로 확인되었다. 컬럼 실험에서는 200 L/d은 0.5 NTU 미만의 탁도에 도달하는데 가장 짧은 시간을 보여주고 있으며, TOC를 제거할 때 가장 작은 처리수로도 가능하였다. 하지만, 100 L/d에서 1.5 ㎎/L의 불소에 도달하는 운전시간은 80분으로 가장 길었다. 그래서 운전시간, bed volume, 에너지 효율 측면에서 100 L/d가 효과적인 운전조건인 것으로 나타났다.
결론: 컬럼을 100 L/d에서 운전할 때 불소제거 측면에서 효과적인 운전조건이다. 그래서 개발도상국에서 골탄을 이용한 불소 제거 정수처리 시설은 저유량으로 운전하는 것이 효과적이다.

다국어 초록 (Multilingual Abstract)

Objectives : Bone char is used in many eastern countries in Africa to remove high levels of fluoride from groundwater. However, due to the low adsorption efficiency of bone char, it is necessary to replace bone char frequently, which cause significant burden to the people in those areas. In this study, we developed a water treatment system to remove high level of fluoride in groundwater using a high efficiency bone char.
Methods : In order to make a high efficiency bone char, cow bones were washed, dried and cut into small pieces. Then the bones were burned for 1, 3 and 5 hours at 350, 450 and 550℃ in electric furnaces. After that, the burned bones were sieved with 600~2,000 μm to match the size of bone char being used in Ethiopia. Surface analysis of bone char was performed using SEM and BET. The removal efficiency of bone char was conducted with various level of turbidity, TOC, and fluoride concentration for 90 minutes under the flow rate conditions of 100, 200, 300, and 400 L/day with an initial fluoride concentration of 4.8 ㎎/L.
Result and Discussion : There was a significant difference between the bone char from Ethiopia and our study in terms of their surface roughness and specific surface area according to SEM and BET analysis. The adsorption capacity of the bone char produced in this study was 3.7 ㎎ F/g, compared to 1 ㎎/L from the one from Ethiopia. In terms of turbidity and organic matter removal with column test, 200 L/d showed the shortest operating time to reach turbidity of less than 0.5 NTU, and was an effective operation for TOC removal. However, It took the longest to 1.5 ㎎/L of fluoride after breakthrough under 100 L/d operating conditions. In terms of operating time, bed volume, and energy efficiency, 100 L/d was found to be an effective operating condition.
Conclusions : We developed a high efficiency bone char in this study with modification of its production process and tested it at various operating conditions. Our study showed that the bone char developed in this study is about 4 times more effective than traditional bone char and it is most effective at operation with low flow rates. Column operation is most effective at 100 L/d for fluoride removal under operating time and bed volume and energy efficiency. Therefore operating condition of drinking water treatment system for the fluorine removal using bone char in developing countries is effective in low flow rate operation.

목차 (Table of Contents)

• 1. 서론
• 2. 실험방법
• 3. 결과 및 고찰
• 4. 결론
• References

참고문헌 (Reference)

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