• Journal of environmental and Sanitary engineering
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• v.13 no.2
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• pp.57-65
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• 1998

In this research, Effect of C/N ratio on nutrient removal in intermittently aerated activated sludge system(IAASS) was investigated with dormitary, building and swine wastewater. Three types (2-stage, 4-stage, modified) of IAASS were operated. Time interval of aeration/nonaeration in IAASS was 1hr/1hr. In treatment of Dormitary wastewater(BOD/T-N ratio : 4.4), Building wastewater (BOD/T-N ratio : 3.14) and swine wastewater(BOD/T-N ratio : 3.84), Nitrogen removal efficiency of 80, 70 and 90.4% was achieved, respectively. Nitrogen removal in IAASS was a great influenced on influent C/N ratio, efficient nitrogen removal was achieved at BOD/T-N ratio over 4. In IAASS operation, $\Delta $BOD mg/L/$\Delta $ nitrogen mg/L ratio was about 4-6. Simultaneous removal of organic, nitrogen and phosphorus in IAASS can achieved. And influent organic was efficiently utilized in denitrification. IAASS could be one of the best alternative process for the retrofit of conventional activated sludge system for the removal of nutrients.

• Environmental Engineering Research
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• v.22 no.4
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• pp.377-383
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• 2017

A tube-type ceramic membrane for microfiltration was developed, and the membrane module comprised of three membranes was also applied to biological carbon and nitrogen removal processes for post-treatment. Manufacturing the microfiltration membrane was successful with the structure and boundary of the coated and support layers within the membrane module clearly observable. Total kjeldahl nitrogen removal from effluent was additionally achieved through the elimination of solids containing organic nitrogen by use of the ceramic membrane module. Removal of suspended solids and colloidal substances were noticeably improved after membrane filtration, and the filtration function of the ceramic membrane could also easily be recovered by physical cleaning. By using the ceramic membrane module, the system showed average removals of organics, nitrogen, and solids up to 98%, 80% and 99.9%, respectively. Thus, this microfiltration system appears to be an alternative and flexible option for existing biological nutrient removal processes suffering from poor settling performance due to the use of a clarifier.

• Clean Technology
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• v.8 no.2
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• pp.77-83
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• 2002

The purpose of this study is to develop the efficient nutrient removal process and to verify operation and design parameters in domestic sewage. Endogenous nitrate respiration (ENR) was used for denitrification of nitrate in return sludge without additional organic carbon source. ENR reactor before the anaerobic tank enable to reduce nitrate below 3 mg/L and increase phosphate release at anaerobic reaction. Primary effluent during pilot scale plant were shown as TCOD/TP ratio of 40~60 and TCOD/TKN ratio of 5~7. Effluent concentrations were 10 to 12mg/L as TN and 1mg/L as TP respectively. In lab scale experiments endogenous denitrification rate of ENR reactor ranges from 0.042 to $0.057gNO_3-N/gMv.d.$ $SP_{rel}/SCOD_{rm}$ was shown as from 0.13 to 0.17 in anaerobic reaction. These kinetic parameters are expected to be available for BNR(Biological Nutrient Removal) plant design and ENR reaction is available for nutrient removal in low strength wastewater.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.5
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• pp.589-599
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• 2007

This study was conducted to investigated the removal efficiency of BOD and nutrient for the treatment of low strength municipal wastewater by a biological nutrient removal system. In this experiment, the effect of operating parameter including HRT of 7.0hr, BOD/TN ratios of 2.62~4.08, internal recycle of 50~300%, and return sludge of 50~100%, were studied during winter season. Efficiencies of organic matter and T-P removal and denitrification were not significantly affected by the change of temperature in winter season. However, the specific nitrification rate and nitrification efficiency decreased at low temperature. Besides, denitrification efficiencies increased with increasing BOD/TN ratios. It was also found that the internal recycle and return sludge ratio below 50% is required for the effective denitrification of low strength municipal wastewater. With operating mode 4 of the optimum, the effluent BOD, T-N and T-P concentration were obtained to average 5.8, 14.6, and 0.84 mg/L, respectively. The temperature-activity coefficient (${\theta}$) of specific nitrification rate, specific denitrification rate and specific phosphorus uptake rate were obtained 1.044, 1.017, 1.028, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.2
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• pp.219-225
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• 2008

Evaluating and designing secondary clarifier require to define characteristics of influent MLSS (Mixed Liquor Suspended Solids). In this study, bioflocculation and settling characteristics for MLSS from a Biological Nutrient Removal (BNR) plant located in near Seoul were measured. MLSS concentrations in bioreactor were about 2,500mg/L in summer and about 4,000mg/L in winter, respectively. Tests showed that there was not much bioflocculation occurred in secondary clarifier. Average ESS/DSS (Effluent Suspended Solids/Dispersed Suspended Solids) was 100%. From the settling tests, ZSV (Zone Settling Velocity) and settling constant (n) in Vesilind equation were estimated at different MLSS temperatures. SVI (Sludge Volume Index) and SSVI (Stirred Sludge Volume Index) were also measured at different temperatures. It was found that ZSV was positively correlated with temperature and n was inversely proportional to temperature. SVI and SSVI had very similar values at about $25^{\circ}C$ of MLSS, However, SVI had more than 2 times higher values than SSVI at below $20^{\circ}C$ of MLSS. Temperature effect must be considered to design and evaluate secondary clarifier.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.647-651
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• 2004

In this study, some of bacterial growth kinetic parameters were delineated and evaluated for the biological nutrient removal processes such as the $A^2/O$, 4stage-BNR, Intermittent Cycle Extended Aeration System(ICEAS) and Intermittently Aerated Cylindrical Oxidation Ditch(IACOD) processes. $Y_H$ values for the ICEAS process ranged from 0.71 to 0.74, and were higher than those for the other processes. It seems to indicated that organic carbons uptaked by microorganism were more used up for cell synthesis rather than for energy components in the ICEAS process. $b_H$ for the ICEAS and IACOD processes were lower than those for $A^2/O$ and 4stage-BNR processes. The $\mu_{max{\cdot}A}$ for the ICEAS was higher than those for the other processes, which indicated that desirable operating conditions for nitrifying bacteria's growth were established.

• Journal of Environmental Health Sciences
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• v.31 no.2 s.83
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• pp.152-159
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• 2005

Laboratory scale experiments were conducted to study the applicability, and to compare the performance of two types of sequencing batch reactor (SBR)systems, a conventional SBR and sequencing batch biofilm reactor (SBBR) on the biological nitrogen and phosphorus removal. The nitrification rate in SaR was higher than that in SBBR both in high influent TOC concentration. The denitrification was completed at the first non-aeration period in SBR, however, the additional non-aeration period should be installed or the first aeration period should be extended more in order to complete the nitrogen removal in SBBR. The time at the first aeration period was more needed as about 4-5 h in order to uptake all the released $PO_4^{3-}\;-P$ at the first non-aeration period. SBBR needed more operation time, especially the first aeration time, than SBR at the high influent TOC concentration in order to complete nitrogen and phosphorus removal.

• Journal of Korean Society on Water Environment
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• v.16 no.4
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• pp.501-512
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• 2000

This study was carried out to develop the new process for RBC process which is capable of nutrient removal and to obtain its design parameters for Sludge Settling Type Rotating Biological Contactors by comparing RBC with RBC combined with HBR (Hanmee Bio-Reactor). To achieve more than 90% of organic removal efficiency, organic loading rate less than $6.0g\;BOD/m^2/d$ is recommended. Nitrification rate was about 90% at $6.0g\;BOD/m^2/d$. TN removal efficiency of RBC+HBR was higher than those of RBC1 and RBC2. TN removal efficiency at condition of $5.0g\;BOD/m^2/d$ was about 60% in RBC1. When BOD loading rate was $6.0g\;BOD/m^2/d$. TN removal efficiencies in RBC2 and RBC+HBR were about 70%, 80%, respectively. TP removal efficiency was more than about 67% for RBC1, about 63% for RBC2 and about 71 % for RBC+HBR at the same loading rate. From the blank experiment to observe removal efficiency in the first stage, it can be known that COD removal efficiency was about 30% and suspend solids settling rate was about 45%. It was proved that RBC+HBR is much better in sludge dewatering than RBC.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.563-570
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• 2004

Phased isolation intrachannel clarifier ditch process developed in this study is an enhanced biological nutrient removal process employing two ditches with intrachannel clarifiers. Bench-scale phased isolation ditch process was used to evaluate the system performance on municipal wastewater and detailed assessment of internal behavior in a ditch and each reactions. When the system was operated at the HRTs of 6~12hours, SRTs of 9~31 days, and cycle times of 4hours, the system showed removals of BOD, TN, and TP as high as 88~97%, 73~78%, and 65~90%, respectively. The internal behavior were well matched on each reactions such as nitrification, denitrification, and phosphorus release and uptake. As the SRT became longer, TN removal increased gradually, whereas TP removal decreased contrarily. However, the system was capable of producing an effluent TP concentration 1mg/L or less even at longer SRTs except the case of solids discharge by malfunction of intra-clarifier occurred by its geometrical limit. The system performance slightly decreased by hydraulic shock loading(increasing of influent flowrate and decreasing of system HRT). However, the higher system performance could be achieved again after four cycles. Thus, the system reliability could be successfully achieved short-term hydraulic shock loading that occurred in medium- and small-sized wastewater treatment plants suffering fluctuation of influent quality and flowrate during wet season.

• Journal of environmental and Sanitary engineering
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• v.13 no.1
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• pp.26-31
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• 1998

Removal of nitrogen and phosphate in wastewater is concerned to important for the prevention of eutrophication in receiving water and lake. Conventional activated sludge system designed for organics removal can be retrofitted only by modification of aeration basin to maintain anaerobic and aerobic state. Biological nutrient removal processes(BNR) such as Bardenpho, A$^{2}$/O, UCT, VIP were generally used for the treatment of wastewater. However these BNR processes used in large scale WWTP were not suitable in small scale WWTP(i.e., package type WWTP) due to relatively large fluctuation of flow rate and concentration of pollutants. The purpose of this research was to develop the compact, effective and economical package type WWTP for the removals of carbon and nitrogen in small scale wastewater. Intermittently aerated activated sludge system (IADFAS) were investigated for removal of nitrogen in both domestic wastewater, Bardenpho process was also evaluated. Nitrogen removal of IAAS, IADFAS, Bardenpho were 75, 77 and 67%, respectively.