• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.4
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• pp.33-40
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• 2021

In this study, the physico-chemical and biological characteristics of anaerobic granular sludge at different heights of a full-scale UASB reactor (UASBr) were investigated. Granular sludge was taken from 1 m, 2 m, and 3 m above the ground level in the UASBr. The morphological analysis showed that the upper part had bigger granules and the lower part had rounder granules. The ANOVA test confirmed that the mean size and the roundness of the granules had statistically significant difference along the height at 95% confidence level, and there was a significant negative linear relationship between the size and roundness (r=-0.40, p<0.05). A SMA test using acetic, propionic and butyric acids showed that granules from 2 m height had the highest specific methanogenic activity. The EPS contents were also unequal to each height, with 2 m showing the highest content. These findings could be helpful to understand the different characteristics of stratified anaerobic granules in full-scale UASBr and maintain the reactor performance.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2020.10a
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• pp.144-144
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• 2020

• Journal of Environmental Science International
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• v.30 no.12
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• pp.1081-1092
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• 2021

In this study, the effect on the stability of Aerobic Granular Sludge (AGS) caused by an AGS separator was investigated. The AGS separator was a hydrocyclone. The main factors of the AGS separator were filter pore size (0.125~0.600 mm), conical-to-cylindrical ratio (1.5~3.0), and operating time (1~20 min). The AGS/mixed liquor suspended solid (MLSS) ratio gradually increased to 0.500 mm (AGS/MLSS: 84.3±3.0%). AGS was best separated at the conical-to-cylindrical ratio of 2.5 (AGS/MLSS: 84.7±3.3%). As the operating time increased, the AGS separation performance also tended to increase. The shortest AGS separator run time, but the highest AGS separation performance was 10 min (87.0±2.5%). AGS stability was evaluated by operating the selected AGS separator and sequencing batch reactor. The average removal efficiencies of TOC, TCOD_Cr, SS, TN, and TP were 95.7%, 96.9%, 93.0%, 89.0%, and 96.2%, respectively, which met the effluent standards in Korea. In addition, the AGS/MLSS ratio tended to remain constant, and the sludge volume index demonstrated a tendency to decrease from 140 mL/g to 70 mL/g. During the operation, the particles of AGS in optical microscope observations gradually increased.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.2
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• pp.79-86
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• 2016

The purpose of this study is to efficiently improve biological sequencing batch reactor (SBR) system of high-concentrated nitrate nitrogen in reverse osmosis (RO) concentrates by total dissolved solids (TDS) regulation. Since a laboratory-scale SBR system had been operated, we had analyzed specific denitrification rate (SDNR) and specific oxygen uptake rate (SOUR) for microbial activity in according to various injection concentration of TDS. As a result, higher injection concentration of TDS decreased SDNR, and delayed denitrification within denitrification process. Moreover, the higher injection concentration of TDS was, the lower microbial activity was during operation of laboratory-scale SBR system. Therefore, the regulation of TDS injection concentration is necessary to improve efficiency of nitrate nitrogen in the biological SBR system, and treatment of calcium ion ($Ca^{2+}$) is also specifically focused to remove nitrate nitrogen. Moreover, analytical data of SDNR and SOUR can be the effective kinetic design parameters to application of biological treatment of RO concentrate by aerobic granular sludge (AGS).

• Journal of Environmental Science International
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• v.32 no.7
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• pp.483-492
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• 2023

In this study, the treatment of livestock wastewater using an aerobic granular sludge based sequencing batch reactor was investigated. The reactor operation was carried out by general injection and split injection methods. The average removal efficiency of organic matter after the adaptation period was 71.5 and 87.4%, respectively. Some untreated organic matter was attributed to recalcitrant organic matter. The average removal efficiency of total nitrogen was 65.6 and 88.4%, respectively. These results indicate that the denitrification reaction by split injection was carried out smoothly. As for the solids, the ratio of aerobic granular sludge/mixed liquor suspended solid can be determined as the main factor of the process operation, and the ratio increased gradually and finally reached 86.0%. Correspondingly, the sludge volume index (SVI) was also improved, reaching 54 mL/g at the end of operation, and it is believed that the application of a short settling time contributed to the improvement of settleability.

• Clean Technology
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• v.18 no.4
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• pp.398-403
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• 2012

Selective nitrification and granulation have been carried out in a pilot scale air-lift sequencing batch reactor (SBR) for stable and economical nitrogen removal from wastewater. The SBR showed about 100% nitrification efficiency up to 1.0 kg ${NH_4}^+-N/m^3{\cdot}d$, about 90% efficiency at 1.0-2.0 kg ${NH_4}^+-N/m^3{\cdot}d$, and it was less than 90% when the load was higher than 2.0 kg ${NH_4}^+-N/m^3{\cdot}d$. Nitrite accumulation was induced by selective inhibition of nitrite oxidizing bacteria by free ammonia inhibition and dissolved oxygen limitation. For the purpose, high nitrite ratio (> 0.95) was obtained by keeping the pH higher than 8.0 and dissolved oxygen lower than 1.5 mg/L. In addition, sludge granulation was achieved by keeping reactor settling time to 5 minutes to wash out poor settling sludge and to promote the growth of granulation sludge. The operation accelerated sludge granulation and the sludge volume index (SVI) decreased and stably maintained to less than 75 in 60 days.

• 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.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.404-408
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• 2003

In this study, hydrogen gas produced by anaerobic mocrobial at anaerobic condition. To maintain the high MLSS concentration, anaerobic sludge was transformed to granular sluge by adding both high molecular cationic polymer(M.W>5,000,000) and silica sol. Hydrogen production was easily distributed, which seemed caused by methane producing microbial. Even low pH control(pH<5.5) was not the effective mean to block methane producing microbial. To decrease of $H_2$ production was closely related with the inclose of $CH_4$ production. Other mean expect for pH control must be devised for the efficient $H_2$ production.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.339-342
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• 2003

In this study , hydrogen gas produced by anaerobic mocrobial at anaerobic condition. To maintain the high MLSS concentration, anaerobic sludge was transformed to granular sluge by adding both high molecular cationic polymer(M.W.>5,000,000) and silica sol. Hydrogen production was easily distributed, which seemed caused by methane producing microbial. Even low pH control(pH<5.5) was not the effective mean to block methane producing microbial. To decrease of $H_2$ production was closely related with the inclose of $CH_4$ production. Other mean expect for pH control must be devised for the efficient $H_2$ production.

• Journal of Environmental Science International
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• v.28 no.8
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• pp.669-676
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• 2019

The purpose of this study was to evaluate the effects of different Hydraulic Retention Times (HRTs) on the contaminant removal efficiency using Aerobic Granular Sludge (AGS). A laboratory-scale experiment was performed using a sequencing batch reactor, and the Chemical Oxygen Demand (COD), nitrogen, orthophosphate removal efficiency, AGS/MLSS ratio, and precipitability in accordance with the HRT were evaluated. As a result, the COD removal efficiency was not significantly different with the reduction in HRT, and at a HRT of 6 h, the removal rate was slightly increased owing to the increase in organic loading rate. The nitrogen removal efficiency was improved by injection of influent division at a HRT of 6 h. As the HRT decreased, the MLSS and AGS tended to increase, and the sludge volume index finally decreased to 50 mL/g. In addition, the size of the AGS gradually increased to about 1.0 mm. Therefore, the control of HRT provides favorable conditions for the stable formation of AGS, and is expected to improve the contaminant removal efficiency with the selection of a proper operation strategy.