• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.172-181
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• 2001

Upflow anaerobic sludge blanket (UASB) system employs granular sludge to treat various wastewaters including landfill leachate. CH$_4$ production of the granules determines overall performance of a UASB reactor. Sludge granules are developed by self-granulation of microorganisms and dynamic balance between granule growth and decay results in coexistence of granules with different sizes in the reactor. In this study, granules taken from a laboratory-scale UASB reactor were classified into 4 groups based on their diameters and their Physicochemical characteristics we were investigated. Each group was analyzed for settling ability, specific methanogenic activity (SMA), and elemental content. Settling ability was proportional to granule diameter. suggesting effective detainment of larger granules in the reactor. When acetate or glucose was used as a substrate, all groups showed relatively slight difference in SMA. However SMA with a volatile fatty acid mixture showed significant increase with granule diameter, suggesting better establishment of syntrophic relationship in larger granules. Larger granules showed higher value of SMA upon environmental changes (i.e., PH, temperature, or toxicant concentration). Comparative analysis of elemental contents showed that content (dry weight %) of most tested elements (iron, calcium, phosphorus, zinc, nickel. and manganese) deceased with granule diameter, suggesting importance of these elements for initial granulation. Taken together, this study verified experimentally that Physicochemical Properties of granules are related to granule size distributions. Overall results of physicochemical characterization supports that larger.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.508-511
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• 2000

In situ hybridization with fluorescent oligonucleotides(FISH) was used to detect and localize microorganisms in the granules of lab-scale upflow anaerobic sludge blanket(UASB) reactors. An UASB reactor was seeded with mesophilically-grown($35^{\circ}\;C$) granular sludge, and thermophilically($55^{\circ}\;C$) operated by feeding with a synthetic wastewater. Sections of the granules were hybridized with 16S rRNA-targeted oligonucleotide probes for Eubacteria, Archaeabacteria, and specific phylogenetic groups of methanogens. FISH clearly showed the layed structure of thermophilic granules, which was consisted of outer bacterial cells and inner archaeal cells. Methanoseata-, Methanosarcina-like cells were also found to be localized inside the granules. These results demonstrated FISH was useful in studying the spatial organizations of methanogens and in situ morphologies and metabolic functions in thermophilic granular sludges.

• 상하수도학회지
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• 제17권4호
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• pp.550-558
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• 2003

Digestion of primary sludge was conducted to evaluate the effects of reactor configuration using UAD, CUAD, TPAD, and semi-continuos CSTR. Highest VSS reduction and gas production were obtained in CUAD at all HRT. More efficient digestion was accomplished in upflow digesters compared to TPAD and CSTR. Higher thickening of solids in reactor and longer solids retention were main reasons for the enhanced digestion in CUAD and UAD. Performance based on the SRT of CUAD was nearly identical to that of UAD. However, those of TPAD and CSTR were lower than that of CUAD. Particulate and soluble organics in upflow reactors were well adsorbed due to secreted extracellular polymeric substances from the sludge granules. These might result in close proximity of microorganisms and substrates and enhanced hydrolysis. Additionally, diverse anaerobic microorganisms and neutral pH in upflow reactor could induce more activity of hydrolytic enzymes and sludge granules might offer lower thermodynamic energy state. While, excessive mixing in CSTR could break conglomerates of enzymes and substrates into fine particles, which resulted in lowered hydrolysis. Low pH level in acid fermenter of TPAD lowered hydrolysis of the particulate substrates.

• Journal of Microbiology and Biotechnology
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• 제13권3호
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• pp.378-384
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• 2003

Mesophilically-grown granular sludge seeded in thermophilic UASB reactor was monitored to better understand the start-up process of the reactor. The reactor was fed with a synthetic wastewater containing glucose. As COD loading rate increased stepwise, methane production rate increased. Maximum values of COD removal efficiency (95%) and methane production rate (5.3 l/day) were achieved by approximately day-80 and remained constant afterward. However, physicochemical and microbial properties of granules kept changing even after day-80. Specific methanogenic activity (SMA) was initially negligible, and increased continuously until day-153 and remained constant afterward, showing the maximum value of $1.51{\pm}0.13\;g\;CH_4-COD/g$ VSS/day. Deteriorated settling ability of granules recovered the initial value by day-98 and was maintained afterward, as determined by sludge volume index. Initially reduced granule size increased until day-126, reaching a plateau of 1.1 mm. Combined use of fluorescence in situ hybridization and confocal laser scanning microscopy (CLSM) allowed to localize families of Methanosaetaceae and Merhanosarcinaceae in granules with time Quantitative analyses of CLSM images of granule sections showed abundance patterns of the methanogens and numerical dominance of Methanosaeta spp. throughout the start-up period. The trend of SMA agreed well with abundance patterns of the methanogens.

• 한국물환경학회지
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• 제29권4호
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• pp.497-503
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• 2013

The morphological characteristics of granules, which were generated in lab-scale sequencing batch reactor (SBR) for simultaneous nitrogen and phosphorus removal with denitrifying phosphorus accumulating organism (dPAO) were identified. Granular sludge was fully developed in the anaerobic-anoxic (An-Ax) SBR after 180 days of SBR operation. The average diameter of granular sludge was 2.2 mm and rod-type organisms dominated in the granules. In addition, about 1.0 mm of white precipitate was observed in the core of the granule, and the material was confirmed that it is very similar to hydroxyapatite $(HAP;\;Ca_5(PO_4)_3(OH))$ by X-ray diffraction) analysis.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.901-908
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• 2002

The relationship between the layered structure of granules in UASB reactors and microbial resistance to toxicity was investigated using disintegrated granules. When no toxic materials were added to the media, the intact and disintegrated granules exhibited almost the same ability to decrease COD and to produce methane. However, when metal ions and organic toxic chemicals were added to a synthetic wastewater, he intact granules were found to be more resistant to toxicity than the disintegrated granules, as determined by the methane production. The difference in resistance between the intact and disintegrated granules was maximal, with toxicant concentrations ranging from 0.5 mM to 2 mM for trichloroethylene with toluene and 5 mM to 20 mM for metal ions (copper, nickel, zinc. chromium, and cadmium ions). The augmented COD removal rate by granulation compared to disintegrated granules was also measured in the treatment of synthetic and real wastewaters; synthetic wastewater, $-2.6\%$; municipal wastewater, $2.8\%$; swine wastewater, $6.4\%$; food wastewater, $25.0\%$; dye works wastewater, $42.9\%$; and landfill leachate, $61.8\%$. Continuous reactor operation also demonstrated that the granules in the UASB reactor were helpful in treating toxic wastewater, such as landfill leachate.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.365-369
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• 2000

반응기의 performance를 결정하는 중요한 요소는 methane 생성균의 활성을 측정하는 것이다. Methanogen의 활성을 측정하는 방법으로 SMA가 유일하게 사용되고 있다. 따라서 본 연구에서는 methanogen의 활성을 측정하는 다른 대안으로 CLSM image의 정량 분석 방법을 확립하였다. CLSM의 결과는 약 5시간 안에 얻을 수 있을 뿐만 아니라, 분자 생물학적인 기술을 많이 요하지 않는다. 또한, sludge내부의 상태와 methanogen의 분포정도를 사진으로 볼 수 있는 장점이 있다. 따라서 SMA와 함께 CLSM image 정량 분석은 UASB반응기의 start-up 동안의 methanogen의 활성을 측정하기 위한 유용한 방법으로 제안할 수 있다.

• Environmental Engineering Research
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• 제19권1호
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• pp.23-29
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• 2014

In this study, aerobic granules were applied to a lab-scale aerobic granule sludge airlift reactor (AGSAR) and the ammonium nitrogen oxidation performance was evaluated at different ammonium nitrogen loading rate (NLR). At least 99% of the initial ammonium nitrogen was oxidized at an NLR of 0.27 and 0.53 kg $NH_4{^+}-N/m^3{\cdot}day$, for both aerobic granules (control), and nitrifying aerobic granules (NAGs). The ammonium nitrogen oxidation deteriorated, when the NLR was increased to 1.07 kg $NH_4{^+}-N/m^3{\cdot}day$. The NAGs were characterized by complete nitrification, while partial nitrification was observed in the control.

• 생명과학회지
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• 제23권5호
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• pp.676-681
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• 2013

퍼클로레이트(${ClO_4}^-$)는 지표수 및 토양/지하수에서 검출되는 신규 오염물이다. 퍼클로레이트 환원세균(PRB)은 ${ClO_4}^-$를 무해한 최종산물로 전환시킬 수 있으므로 ${ClO_4}^-$ 제거는 미생물을 이용한 방법이 가장 적절한 것으로 알려졌다. 이전 연구[3]를 통해 원소 황 입자와 활성슬러지를 이용하여 독립영양방식의 ${ClO_4}^-$ 제거가 가능하다는 실험적 증거가 제시되었다. 입자상 황은 비교적 값이 저렴하고, 활성슬러지는 하수처리장으로부터 쉽게 구할 수 있는 장점이 있다. 그래서 본 연구에서는 원소 황을 전자공여체로 사용하였을 때 여러 환경요인이 활성슬러지 미생물의 ${ClO_4}^-$ 분해에 미치는 영향을 회분반응으로 조사하였다. 이 회분반응의 결과를 통해 활성슬러지 미생물에 의한 독립영양방식의 ${ClO_4}^-$ 분해를 위한 최적조건을 도출하였다. 또한 활성슬러지로부터 농화배양된 황산화 PRB는 활성슬러지보다 ${ClO_4}^-$ 제거능이 우수한 것으로 회분반응 결과 나타났다. 그래서 본 연구결과는 최적조건 적용 및 농화배양된 접종균을 통해 원소 황과 활성슬러지를 이용한 독립영양방식의 ${ClO_4}^-$ 제거를 향상할 수 있다는 것을 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.849-853
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• 2002

Metal ions have an adverse effect on anaerobic digestion. In an acetate degradation test of upflow of anaerobic sludge blanket granules with $Cu^{2+}$, not all of the acetate that disappeared was stoichiometrically converted to methane. In the presence of 400 mg/g-VSS (volatile suspended solids) $Cu^{2+}$, only 26% of the acetate consumed was converted to methane. To study acetate conversion by other anaerobic microorganisms, sulfate and nitrate reductions were investigated in the presence of $Cu^{2+}$ Sulfate and nitrate reductions exhibited more resistance to $Cu^{2+}$than methanogenesis, and the granules reduced 2.2 mM and 5.4 mM of nitrate and sulfate, respectively, in the presence of 400 mg/g-VSS copper ion. However, the acetate degraded by sulfate and nitrate reductions was only 24% of the missing acetate that could have been stoichiometrically converted to $CO_2$. Accordingly, 76% of the acetate consumed appeared to have been converted to other unknown compounds.