• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.343-346
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• 2000

This study was carried out to investigate the effects of influent $NH_4^{\;+}-N$ load, C/N ratio and superficial air velocity on the nitrogen removal efficiencies. Laboratory scale upflow biological aerated filter(BAF) was consisted of an anoxic-aerobic filter packed with porous ceramic media and operated with synthetic wastewater. BAFs requires less energy and space for the system when compared to conventional activated sludge process. The influent C/N ratios were varied from 0 to 1 by adjusting acetate. Various superficial air velocity had been applied to investigate aeration effect on nitrogen removal. The BAF reactor showed more than 90% average $NH_4^{\;+}-N$ removal efficiencies at $NH_4^{\;+}-N$ loading in the range of $0.26{\sim}1.33$ kg $NH_4^{\;+}-N/m^3{\cdot}d$ and 62% average T-N removal efficiencies at the C/N ratio of 1. Moreover, average T-N removal efficiencies increased as the superficial air velocity increased, because of the increase $NH_4^{\;+}-N$ removal efficiencies.

• Korean Journal of Environmental Agriculture
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• v.28 no.4
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• pp.371-377
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• 2009

In this study, simultaneous nitrification and denitrification (SND) from synthetic wastewater were performed to evaluate dissolved oxygen(DO) effects on chemical oxygen demand(COD) and nitrogen removal in a single membarne bio-reactor(MBR). DO levels in MBR at Run 1, 2, and 3 were 1.9~2.2, 1.3~1.6, and 0.7~1.0 mg/L, respectively. Experimental results indicated that DO had an important factor to affect COD and total nitrogen(TN) removal. SND were able to be accomplished in the continuous-aeration MBR by controlling ambient DO concentration. It is postulated that, because of the oxygen diffusion limitation, an anoxic micro-zone was formed inside the flocs where the denitrification might occur. From the results of this study, 96% of COD could be removed at DO of 0.7mg/L. At run 2 72.92% of nitrogen was removed by the mechanisms of SND (7.75mg-TN/L in effluent). In this study, SND was successfully occurred in a MBR due to high MLSS that could help to form anoxic zone inside microbial floc at bulk DO concentrations of 1.3~1.6mg/L.

• Journal of Environmental Science International
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• v.22 no.1
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• pp.1-6
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• 2013

A fixed biofilm reactor system composed of anaerobic, anoxic(1), anoxic(2), aerobic(1) and aerobic(2) reactor was packed with synthetic activated ceramic (SAC) media and adopted to reduce the inhibition effect of low temperature on nitrification activities. The changes of nitrification activity at different wastewater temperature were investigated through the evaluation of temperature coefficient, volatile attached solid (VAS), specific nitrification rate and alkalinity consumption. Operating temperature was varied from 20 to $5^{\circ}C$. In this biofilm system, the specific nitrification rates of $15^{\circ}C$, $10^{\circ}C$ and $5^{\circ}C$ were 0.972, 0.859 and 0.613 when the specific nitrification rate of $20^{\circ}C$ was assumed to 1.00. Moreover the nitrification activity was also observed at $5^{\circ}C$ which is lower temperature than the critical temperature condition for the microorganism of activated sludge system. The specific amount of volatile attached solid (VAS) on media was maintained the range of 13.6-12.5 mg VAS/g media at $20{\sim}10^{\circ}C$. As the temperature was downed to $5^{\circ}C$, VAS was rapidly decreased to 10.9 mg VAS/g media and effluent suspended solids was increased from 3.2 mg/L to 12.0 mg/L due to the detachment of microorganism from SAC media. And alkalinity consumption was lower than theoretical value with 5.23 mg as $CaCO_3$/mg ${NH_4}^+$-N removal at $20^{\circ}C$. Temperature coefficient (${\Theta}$) of nitrification rate ($20^{\circ}C{\sim}5^{\circ}C$) was 1.033. Therefore, this fixed film nitrogen removal process showed superior stability for low temperature condition than conventional suspended growth process.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.275-280
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• 2011

In the present work, the aerobic particle's characteristics were enhanced. A polymer was used to make aerobic granular sludge in short period of time. And operation parameters were calculated for organic matter removal in domestic wastewater using a sequencing batch reactor (SBR). The experiment for sewage (Influent concentration of 63~72 mg COD/L) by using mature aerobic granular sludge showed the organic matter removal rate k and oxygen utilization coefficient a', b' were $10.161d^{-1}$ and 0.87 mg $O_2/mg$ $COD_r$, 0.11 mg $O_2/mg$ MLVSS d respectively. Therefore, it was more effective than K value $5{\sim}8d^{-1}$ of conventional activated sludge process. The sludge synthetic value and sludge auto-oxydation value were 0.45 mg VSS/mg $COD_r$ and 0.05 mg VSS/mg MLVSS d respectively. Consequently, mortality rates of microorganisms was lower than conventional activated sludge process.

• Journal of Korean Society on Water Environment
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• v.21 no.5
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• pp.458-463
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• 2005

Considering the characteristics of a filtration bio-reactor equipped with a mesh filter module which can effectively maintain high concentration of biomass and enhanced solid-liquid separation performance, the hybrid process of filtration bio-reactor combined with coagulation was investigated to get improved filtration characteristics as well as water quality in this work. Two bio-reactors (Run-1 & Run-2) were operated under the following conditions: working volume of 25 L, continuous loading of a synthetic wastewater (BOD: 200 mg/L, T-N: 50 mg/L, T-P: 5 mg/L), where an appropriate amount of alum ($Al_2(SO_4)_3{\cdot}18H_2O$) was added once a day into the reactor (Run-2). In the system without using a alum (Run-1), the clogging of mesh filter module was observed two times through 85 days of whole operation. Meanwhile, the filter module did not clog even at higher MLSS concentration (6,000~12,000 mg/L) and the stable filtration (0.7 mid) was continued in the case of using a alum. Due to the stable formation of cake layers, BOD and SS were shown below 6 and 3 mg/L, respectively. T-P and pH of the effluent were changed because of the intermittent addition of the alum. In the case of Al/P=2.5, the average T-P removal efficiency per day was 85.2% and the average T-P concentration of the effluent was 0.3 mg/L. However, the removal efficiency of phosphate was influenced by pH in the reactor.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.689-696
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• 2007

Kinetic analysis was important to develope the biological nutrient removal process effectively. In this research, anoxic-anaerobic-aerobic system was operated to investigate kinetic behavior on the nutrient removal reaction. Nitrification and denitrification were important microbiological reactions of nitrogen. The kinetics of organic removal and nitrification reaction have been investigated based on a Monod-type expression involving two growth limiting substrates : TKN for nitrification and COD for organic removal reaction. The kinetic constans and yield coefficients were evaluated for both these reactions. Experiments were conducted to determine the biological kinetic coefficients and the removal efficiencies of COD and TKN at five different MLSS concentrations of 5000, 4200, 3300, 2600, and 1900 mg/L for synthetic wastewater. Mathematical equations were presented to permit complete evaluation of the this system. Kinetic behaviors for the organic removal and nitrification reaction were examined by the determined kinetic coefficient and the assumed operation condition and the predicted model formulae using kinetic approach. The conclusions derived from this experimental research were as follows : 1. Biological kinetic coefficients were Y=0.563, $k_d=0.054(day^{-1})$, $K_S=49.16(mg/L)$, $k=2.045(day^{-1})$ for the removal of COD and $Y_N=0.024$, $k_{dN}=0.0063(day^{-1})$, $K_{SN}=3.21(mg/L)$, $k_N=31.4(day^{-1})$ for the removal of TKN respectively. 2. The predicted kinetic model formulae could determine the predicted concentration of the activated sludge and nitrifier, investigate the distribution rate of input carbon and nitrogen in relation to the solid retention time (SRT).

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1455-1462
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• 2012

The vertical distributions of nitrifying bacteria in aerobic fixed biofilm were investigated to evaluate the relationship between nitrification performance and microbial community at different HRT. Fluorescent in situ hybridization (FISH) and portable ion selective microelectrode system were adopted to analyze microbial communities and ions profiles according to the biofilm depth. Cilia media packed MLE (Modified Ludzack-Ettinger) like reactor composed of anoxic, aerobic I/II was operated with synthetic wastewater having COD 200 mg/L and $NH_4{^+}$-N mg/L at HRT of 6 hrs and 4 hrs. Total biofilm thickness of aerobic I, II reactor at 4 hrs condition was over two times than that of 6 hrs condition due to the sufficient substrate supply at 4 hrs condition (6 hrs; aerobic I 380 ${\mu}m$ and II 400 ${\mu}m$, 4 hrs; aerobic I 830 ${\mu}m$ and II 1040 ${\mu}m$). As deepen the biofilm detection point, the ratio of ammonia oxidizing bacteria (AOB) was decreased while the ratio of nitrite oxidizing bacteria (NOB) was maintained similar distribution at both HRT condition. The ratio of AOB was higher at 4 hrs than 6 hrs condition and $NH_4{^+}$-N removal efficiency was also higher at 4 hrs with 89.2% than 65.4% of 6 hrs. However, the ratio of NOB was decreased when HRT was reduced from 6 hrs to 4 hrs and $NO_2{^-}$-N accumulation was observed at 4 hrs condition. Therefore, it is considered that insufficient HRT condition could supply sufficient substrate and enrichment of AOB in all depth of fixed biofilm but cause decrease of NOB and nitrite accumulation.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.3
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• pp.199-204
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• 2006

The purpose of this work was to evaluate the development of the anammox process by the use of granular sludge selected from a digestion reactor as a potential seed source in a lab-scale UASB (upflow anaerobic sludge blanket) reactor system. The reactor was operated for approximately 11 months and was fed by synthetic wastewater. After 200 days of feeding with $NH_4^+\;and\;NO_2^-$ as the main substrates, the biomass showed steady signs of ammonium consumption, resulting in over 60% of ammonium nitrogen removal. This report aims to present the results and to more closely examine what occurs after the onset of anammox activity, while the previous work described the start-up experiment and the presence of anammox bacteria in the enriched community using the fluorescence in situ hybridization (FISH) technique. By the last month of operation, the consumed $NO_2^--N/NH_4^+-N$ ratio in the UASB reactor was close to 1.32, the stoichiometric ratio of the anammox reaction. The obtained results from the influent-shutdown test suggested that nitrite concentration would be one key parameter that promotes the anammox reaction during the start-up enrichment of anammox bacteria from granular sludge. During the study period, the sludge color gradually changed from black to red-brownish.

• KSBB Journal
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• v.18 no.2
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• pp.111-116
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• 2003

Hydrogen producing acidogenic microorganisms were self-immobilized using organic-inorganic hybrid polymer within 5 minutes. During the continuous tratment of synthetic wastewater at a hydraulic retention time of 20 hours, at 37$^{\circ}C$, pH 5.0, the self-immobillized granules were maintained in a stirred tank reactor. The black colored granules gradually became milky. Image analysis showed that the mean diameter of the milky colored granules ranged from 1.5 to 20. mm. The maximum bio-gas procuction rate was 380 ml/L/hy and the concentration of H$_2$was around 50%, while no methane was detected. Granular ECP was extracted and its content was measured to elucidate the role of the organic-inorganic hybrid polymer. Further increases of granule concentration are expected to increase the hydrogen production rate.

• Journal of Aquaculture
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• v.16 no.2
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• pp.76-83
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• 2003

To improve the efficiency of removal of bacteria and virus with DynaSand Filters used for treatment of recycling wastewater from aquaculture, effect of biofilm formation on bacterial transport through coated sand was estimated. At the neutral pH (pH 7.0), the coated sand was positive of zeta potential (surface charge). Column experiments were also carried out to test the effect of uncoated sand as well as coated sand with Al and Fe. The coated sand influenced more significantly the surface properties, adsorption and transport than the uncoated sand. The leaching batch system investigated for synthetic water showed concentrations of 7.47, 4.80, 20.89 and 7.23 mg/L for the uncoated sand, coated sand with Al, Fe and Al+Fe, respectively. Hence there are significant differences among the tested coatings with reference to bacterial transport and surface properties.