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개체군수지 모델을 이용한 기포와 다공성 탄소의 충돌 및 부상 효율 평가
정흥조 ( Heung-joe Jung ),이재욱 ( Jae-wook Lee ) 한국환경기술학회 2020 한국환경기술학회지 Vol.21 No.6
In this work, porous carbons with high surface area were prepared from giant Miscanthus through simple carbonization and activation processes. Adsorption equilibrium and kinetic data of methylene blue on the prepared carbon samples were well fitted with isotherm and kinetic models. On the other hand, the removal efficiency of porous carbons in DAF (dissolved air flotation) was evaluated based on the population balance model. Results showed that the zeta potential was highly sensitive depending on the water properties and coagulation conditions. It was also found that the collision efficiency of bubble-carbon particles in terms of zeta potential was successfully simulated by the employed population balance model.
미세플라스틱 분리를 위한 미세기포 부상공정에서 개체군수지를 이용한 초기 부착 계수 및 부상특성의 평가
정흥조 ( Heung Joe Jung ),이재욱 ( Jae Wook Lee ),곽동희 ( Dong Heui Kwak ) 한국물환경학회(구 한국수질보전학회) 2021 한국물환경학회지 Vol.37 No.1
In the flotation process to remove microplastic (MP) particles, the attachment and separation efficiency is determined by the basic physicochemical characteristics of MP particles as well as bubbles. To evaluate the flotation characteristics of MP particles, we carried out a series of simulations using the population balance (PB) model. The initial attachment coefficient (α<sub>o</sub>) of MP particles was in the range of 0.2-0.275, and it was slightly lower than that of typical particles, such as clay, debris and algae particles, which exist in water bodies, α<sub>o</sub>, 0.3-0.4. The relative bubble number (RBN) attached to the surface of the typical number of bubbles was 0.30 and 0.32 for MP 30 μm and MP 58 μ m, respectively. In comparison, the RBN of larger MP particles (138 μm) was as high as 0.53. Furthermore, smaller microbubbles were required to separate properly or additional treatment needed to be applied to enhance collision and attachment efficiency since the flotation of MP particles was found to be difficult to treat as high-rate. As a result of comparing the removal rate (experimental value) of MP particles obtained from the batch-type flotation apparatus and the flotation removal rate (predicted value) of MP obtained through the PB model, the final particles by the particle size of MP overall except for the initial separation time area. With respect to the removal efficiency, the observed and predicted values were similar, and it was confirmed that the floating separation characteristics and evaluation of the MP particles through the PB model could be possible.
미세기포 부상분리 공정에서 미세플라스틱 분리를 위한 단일포집자 충돌 모델의 적용성 평가
장민호(Min-Ho Jang),최용호(Yong-Ho Choi),정흥조(Heung-Joe Jung),정용훈(Yong-Hoon Jeong),곽동희(Dong-Heui Kwak) 대한환경공학회 2021 대한환경공학회지 Vol.43 No.1
목적: 단일포집자 충돌(SCC) 모델은 입자분리공정에서 미세기포와 입자 간의 충돌효율에 기초하여 입자의 분리효율을 예측하는 모델이다. 최근 위해가 알려진 미세플라스틱(MPs) 입자제거를 위하여, SCC 모델을 토대로 미세플라스틱의 충돌 및 분리효율을 해석해 보고 그 적용 타당성을 평가하고자 하였다. 방법: SCC 모델을 토대로 MPs 입자의 충돌효율 예측을 모의하고, 분리효율을 평가하였다. 아울러, 수중에 부유된 MPs 입자를 제거하기 위해 미세기포를 분사하는 부상분리 장치를 이용하여 일련의 부상분리 실험을 실시하고 그 실험결과와 예측값을 비교하였다. 결과 및 토의 : SCC 모델을 이용하여 MPs 크기분포에 따른 충돌효율은 수중의 통상적 입자(점토, 카올린)와 크게 다르지 않았다. 이 충돌효율을 기초로 수체로부터 분리되는 MPs 입자의 최대 제거 효율은 약 90%에 달할 것으로 예측되었다. 반면, SCC 모델로 확인된 MPs 입자의 초기 충돌-부착 계수(αpb)는 0.03 ~ 0.1로서 0.3 ~ 0.4 범위를 보이는 점토 입자와 다소 큰 차이를 보였다. 이 초기 충돌-부착계수를 적용하여 평가 예측한 MPs의 부상분리 효율은 실측값과 유사한 범위를 나타내었다. 또한 입자분리 효율 향상을 위하여 실측한 기포체적농도의 증가에 따른 입자분리효율도 예측값과 유사한 패턴을 보였다. 결론: 부상분리 공정에서 SCC 모델로 예측한 MPs 입자의 초기 충돌-부착효율은 kaolin 입자에 비하여 낮은 값을 나타내었으며, 미세기포 부상실험 장치를 이용하여 얻은 실측값과 SCC 모델에 의한 모의값을 비교한 결과, 단순하고 간편한 모델인 SCC 이론을 바탕으로 MPs 입자의 부상분리 해석에 적용이 가능함을 확인하였다. Objectives : The single collector collision (SCC) model is a model that predicts the separation efficiency of particles based on the collision efficiency between microbubbles and particles in the particle separation process. In order to remove micro-plastics (MPs) particles, which have recently been known to be harmful, we tried to analyze the impact and separation efficiency of MPs based on the SCC model and evaluate its application feasibility. Methods : Based on the SCC model, the collision efficiency prediction for MPs particle removal was simulated and the separation efficiency was evaluated. In addition, a series of flotation experiments were conducted using a flotation device that injects microbubbles to remove MPs particles suspended in water, and the experimental results and predicted values were compared. Results and Discussion : Using the SCC model, the collision efficiency according to the size distribution of MPs particles was not significantly different from that of typical particles (clay, kaolin) in water. Based on this collision efficiency, the maximum removal efficiency of MPs particles separated from the water body is predicted to reach about 90%. On the other hand, the initial collision-adhesion coefficient (αpb) of the MPs particles based on the SCC model was 0.03 to 0.1, showing a slight difference from the clay particles having the range of 0.3 to 0.4. The flotation separation efficiency of the MPs particles evaluated and predicted by applying this initial collision-adhesion coefficient showed a range similar to the measured value. In addition, the particle separation efficiency according to the increase of the measured bubble volume concentration to improve the particle separation efficiency also showed a pattern similar to the predicted value. Conclusions : In the flotation process, the initial collision-adhesion efficiency of the MPs particles predicted by the SCC model was lower than that of the kaolin particles. Based on the simple and simple model SCC theory, it was confirmed that it can be applied to the flotation separation analysis of MPs particles.