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UASB 공법에 있어서 반응조의 형상변화에 따른 입상슬러지의 특성에 관한 연구
민경석,안영호,Min, Kyung Sok,Ahn, Young Ho 대한토목학회 1994 대한토목학회논문집 Vol.14 No.3
본 연구에서는 UASB 반응조의 형상변화에 따른 입상슬러지의 물리 화학적 및 형태학적인 특성이 조사되었다. 또한 반응조내의 수소분압의 크기에 따른 반응조운전의 안정성이 조사되었다. 수소분압이 높게 유지된 수정개발된 UASB 반응조의 경우가 상대적으로 수소분압이 낮게 유지된 일반적인 UASB 반응조의 경우에 비해 입상슬러지의 침전성 및 미생물보유능이 더 우수하게 나타났다. 입상슬러지의 형성과 그 안정성에 수소분압이 큰 영향을 미치는 것으로 나타났다. 입상슬러지의 화학적 조성식은 일반적인 UASB 반응조와 수정개발된 UASB 반응조가 각각 $C_7H_{12}O_{4.6}N$과 $C_5H_9O_3N$으로, 일반적인 미생물의 경험식인 $C_5H_7O_2N$과는 상이하게 나타났다. 특히 수정개발된 UASB 반응조의 경우 입상슬러지내에 질소성분이 일반적인 혐기성 미생물보다 높게 나타나, 입상슬러지의 발생기작으로서 polypeptide계 체외폴리머의 존재가능성을 보여주고 있다. 전자현미경을 이용한 형태화적 특성조사결과, 일반적인 반응조의 경우와는 달리 수소분압이 높게 유지된 수정개발된 UASB 반응조의 경우 입상슬러지의 표면에서는 Methanobrevibactor arboriphilus와 같은 크기와 형태를 한 수소이용메탄균의 성장이 다발을 이루며 관찰되었는데, 이러한 현상은 입상슬러지의 형성 메커니즘을 뒷받침해주고 있다. 우수한 입상슬러지의 형성을 위해서는 상대적인 수소분압의 크기에 따른 효과적인 상분리가 이루어져, acetogens과 수소이용메탄균들간의 공생관계가 잘 유지되도록 해주어야 할 것으로 사료된다. 수정개발된 UASB 반응조가 일반적인 UASB 반응조에 비하여 수소이용메탄균의 성장에 더욱 효과적인 환경을 제공하는 것으로 판단되며, 입상슬러지의 경영성과 반응조 전체의 유기물질 제거효율 뿐만 아니라, 운전의 안정성 측면에서도 더 우수한 것으로 사료된다. Physicochemical and morphological characteristics of biopellets produced in "control" and modified UASB reactor were investigated to compare the reactor performance with regard to the hydrogen partial pressure. The characteristics of biopellet produced in modified UASB reactor operated with high hydrogen partial pressure were better than those of "control" reactor operated with relatively lower hydrogen partial pressure, therefore the hydrogen partial pressure effected greatly on the formation and stability of the biopellet. Furthermore, pellets from the UASB system with modified settler showed a better settleability and biomass holding capacity. The chemical composition of biopellet was distinctively different from that of common bacterial formula, $C_5H_7O_2N$. Biopellets was composed the large fraction of nitrogen in comparison with common anaerobic microbes. These results implicated the existence possibility of polypeptide-type extracellular polymer. The morphological characterization with SEM showed that microorganisms observed at surface of biopellet produced in modified UASB reactor operated with high $P_{H_2}$ condition were very similar in shape and size to the Methanobrevibactor arboriphilus-$H_2$ utilizing methanogen. The microorganisms was distinguished from those of "control" reactor operated with low $P_{H_2}$ condition. From these results, it could be explained the hydrogen partial pressure effects on pelletization mechanism.
고효율 UASB 반응조에 있어서 반송에 의한 입상슬러지의 특성변화
민경석,안영호 ( Kyung Sok Min,Young Ho Ahn ) 한국물환경학회 1996 한국물환경학회지 Vol.12 No.4
Recycle effects on physicochemical and morphological characteristics of biopellets produced in enhanced UASB(EUASB) reactor were investigated and a simplified method for evaluation of pelletized degree and physical characteristics of biopellet was proposed. The pellets produced from the EUASB system operated with recycle ratio, R = 2 showed a better settleability and biomass holding capacity. Relationship between settleability and biomass holding capacity of pellets was little dependent with ash contents. As ultimate analysis, mass fractions of carbon, nitrogen and oxygen were shown a little different with regard to recycle ratio. And COD/VSS of pellets was affected mass fractions of carbon and nitrogen. The morphological characterization with SEM showed that the consortium of microorganisms was very dependent with hydrogen partial pressure and operational conditions.
민경석,안영호 ( Kyung Sok Min,Young Ho Ahn ) 한국물환경학회 1996 한국물환경학회지 Vol.12 No.4
In this study, hydrogen partial pressure effects on formation of anaerobic biopellets were investigated. So, two-in-series UASB system with well defined biopellets was operated with acetic and propionic acid mixture( 1:1 as COD base) as substrate. As decrement of the hydrogen partial pressure in two-in-series UASB system, it could be observed a lot of biomass discharge from the first stage reactor, damaged biopellets in the second stage reactor, and dispersed sludges in settler. These were reflected in necessity of high hydrogen partial pressure as a key condition for pelletization process. Particularly, the evidence on growth of hydrogenotrophs and extracellular polymer excretions could not be found. And autolysis of microorganisms in declining growth or endogenous stage was observed in the second stage reactor with settler.
민경석,안영호,남광현 ( Kyung Sok Min,Young Ho Ahn,Kwang Hyun Nam ) 한국물환경학회 1997 한국물환경학회지 Vol.13 No.1
In application of enhanced UASB(EUASB) reactor using fat-free milky waste(carbohydrate:protein=60:40) as substrate, degradation of carbohydrate showed priority as compared with that of protein. In HRT 20hrs, maximum SCOD removal was 92% at organic loading rate of 8 ㎏COD/㎥/d. For SCOD removal of 80% over in HRT 10hrs, allowable organic loading rate was to 20㎏COD/㎥/d and then, methane production was 0.27 ℓ CH₄/gCOD-(rm). Enhanced UASB reactor showed phase separation in hydrogen partial pressure phase, but at the lower sludge bed zone, nitrogen utilization was different with that of l00% carbohydrate. It might be due to deamination stage of protein. At the upper sludge bed and blanket zone, it could be found autolysis of organisms except for substrate as well as deamination process. Morphological characterization with SEM showed that biopellets with milky waste was less uniform and packed loosely. These characteristics might be due to deficient condition of directly utilizable nitrogen for production of extracellular materials as well as utilization priority between carbohydrate and protein involved in substrate.
민경석(Kyung Sok Min),정용준(Yong Jun Jung) 한국물환경학회 2001 한국물환경학회지 Vol.17 No.6
The objectives of this study were to investigate the process performance of a bench-scale denitrifying sand filter like maximum filtration rate and effluent concentration with the variation of influent quality and to estimate its applicability for the add-on treatment process of BNR effluent polishing. During the whole experimental periods, SS, Turbidity and NO₃^--N concentration of effluent were obtained less than 2.5 ㎎/L, 2.5 NTU and 6.3 ㎎/L, respectively. The removal efficiency of NO₃^--N could be gradually increased from 78% to 91% by varing the requirements of theoretical external carbon source, which was in the range of 80% and 100%. In both cases that influent NO₃^--N was ranged from 10 to 15 ㎎/L at the filtration rate of 151.3∼171.1 m/d and NO₃^--N was 28.2 ㎎/L at the rate of 111.8 m/d, the NO₃^--N removal efficiencies were 78%, respectively. It is noticed that influent concentration of NO₃^--N was an important factor for NO₃^--N removal efficiency as well as filtration rate. Regardless of influent concentration and filatration rate, SS and Turbidity were less than 2.5 ㎎/L and 2.5 NTU, respectively. Therefore denitrifying sand filter could be of use an alternative post denitrification process targeting for the removal of SS as well as nitrogen.