水素分壓이 슬러지 粒狀化 및 粒狀 슬러지 活性度에 미치는 影響

Abstract

Granular sludge formation and its activity change are the most important factors in achieving successful start-up and stable operation of UASB reactor. Nevertheless, the detailed mechanism and its activity change are still unknown. On the basic of the experiments in laboratory-scale UASB reactor, the effect of hydrogen partial pressure on sludge granulation and activity change were evaluated. 1. The granulation of sludge in UASB reactor closely related to the hydrogen partial pressure. However, the granulation of the sludge was not stimulated in the condition of either the sufficient or deficient hydrogen concentration in the reactors. 2. At the constant hydrogen loading the granulation increased as starvation period in hydrogen supply increased, resulting in high organic removal efficiency. And at the constant starvation period in hydrogen supply, the rate of granulation becomes low as the hydrogen feeding period increased. However, the granulation rate was accelerated when hydrogen supply was stopped after continuous supply of hydrogen. 3. When the sludge was exposure to hydrogen deficient condition after inducing excess production of hydrogen utilizing bacteria in reactor, sludge granulation was remarkably accelerated. It was evident that sludge granulation was achieved through mutual symbiosis between hydrogen utilizing bacteria and hydrogen producing bacteria under the hydrogen deficient conditions. 4. Change in the amount of the remaining solid with the different liquid upflow velocity and in the specific metabolic activity of the sludge with the operation time can be used as an effective means for estimating the degree of the sludge granulation. 5. Organic removal activity of granular sludge decreased as the hydrogen partial pressure increased. The degree of decrease in the activity increased as the substrate concentration in the reactor increased. 6. The difference of sludge activity depend on the size distribution of the granular sludge when evaluating the organic removal performance in the reactor in which only granular sludge and natural granular sludge were seeded. From these results, it was evident that one of the factors in improving an organic removal efficiency through an effluent recirculation system was due to formation of vertical size distribution of granular sludge in reactor. 7. The effluent recirculation was prerequisite for the efficient performance of UASB reactor. This trend was more clear as the higher organic loading was applied.