• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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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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• 2000.11a
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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.

• Journal of Korean Society of Water and Wastewater
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• v.17 no.4
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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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• v.13 no.3
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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.

• Journal of Korean Society on Water Environment
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• v.29 no.4
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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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• v.12 no.6
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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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• 2000.04a
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• pp.365-369
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• 2000

Methanogenic activity of granular sludge was monitored by specific methanogenic activity (SMA) assay and confocal laser scanning microscopy (CLSM) during start-up of a thermophilic UASB reactor. Autofluorescence by CLSM could visualize the methanogenic bacterial population inside sludge granules and its intensity was proportional to SMA. Considering the complex procedures of SMA measurement, fluorescence quantification by CLSM can be suggested as a routine technique measuring methanogenic activity in UASB granules.

• Environmental Engineering Research
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• v.19 no.1
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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.

• Journal of Life Science
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• v.23 no.5
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• pp.676-681
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• 2013

Perchlorate (${ClO_4}^-$) is an emerging contaminant found in surface water and soil/groundwater. Microbial removal of perchlorate is the method of choice since perchlorate-reducing bacteria (PRB) can reduce perchlorate to harmless end-products. A previous study [3] showed experimental evidence of autotrophic perchlorate removal using elemental sulfur granules and activated sludge. The granular sulfur is a relatively inexpensive electron donor, and activated sludge is easily available from a wastewater treatment plant. A batch test was performed in this study to further investigate the effect of various environmental parameters on the perchlorate degradation by sludge microorganisms when elemental sulfur was used as electron donor. Results of the batch test suggest optimum conditions for autotrophic perchlorate degradation by sludge microorganisms. The results also show that sulfur-oxidizing PRB enriched from activated sludge removed perchlorate better than activated sludge. Taken together, this study suggests that autotrophic perchlorate removal using elemental sulfur and activated sludge can be improved by employing optimized environmental conditions and enrichment culture.

• Journal of Microbiology and Biotechnology
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• v.12 no.5
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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.