• Journal of Environmental Science International
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• v.16 no.7
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• pp.813-821
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• 2007

Laboratory scale experiments were conducted to investigate the removal characteristics of nitrogen and phosphorus in two sequencing batch biofilm reactors (SBBRs). SBBR1 had a short first non-aeration period and SBBR2 had a long first non-aeration period. The removal characteristics of nitrogen and phosphorus in each SBBR were precisely observed according to the variation of influent TOC concentration, and the operation control parameters (pH, DO concentration, ORP) in each reactor were measured. In biological nitrogen removal, there was little difference between SBBR1 and SBBR2 and the nitrogen removal efficiencies were very low. The nitrogen and phosphorus removal characteristics in high influent TOC concentration were different from those in low TOC. Nitrogen removals by simultaneous nitrification/denitrification (SND) were occurred in both SBBR1 and SBBR2. The P removal in SBBR1 was superior to that in SBBR2. The second P release was observed in SBBR1 which had long second non-aeration period.

• KSBB Journal
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• v.15 no.5
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• pp.444-451
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• 2000

Nonliving methanotrophic biomass was used as biosorbent to remove lead which is one of representative pollutants in metal-bearing wastewater. Solution pH, maximum uptake, biosorbent dose and ionic strength were considered as major factors for adsorption experiments. The optimum pH range for lead removal was increased 3.8∼11.0 for methanotrophic biomass compared to biosorbent-free control, pH of 8.4∼11.2. Removal efficiency of lead by methanotrophic biomass was pH dependent, but less sensitive than that of control. In isotherm experiments with 0.2g biosorbent/L at initial solution pH 5.0, methanotrophic biomass took up lead from aqueous solutions to the extent of 1085 mg/g biomass. Removal amount of lead increased with an increase of biomass dose. According to biomass dose for initial 1000 mg Pb/L at initial pH 5.0, the optimum amount of biomass for maximum lead removal per unit methanotrophic biomass was 0.2 g biomass/L. As a result of scanning electron microscope (SEM) micrographs equipped with energy dispersive spectroscopy (EDS), lead removal by methanotrophic biomass seemed to be through adsorptions on the surface of methanotrophic biomass and exopolymers around the biomass. EDS spectra confirmed that lead adsorption appeared on the biomass and exopolymers that may be effective to lead removal comparing before and after contact with lead. Removal efficiency of lead was slightly affected by ionic strength up to 2.0 M of NaCl and NaNO$_3$respectively.

• Membrane and Water Treatment
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• v.15 no.1
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• pp.1-9
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• 2024

Biological nutrient removal is gaining increasing attention in wastewater treatment plants; however, it is adversely affected by low temperatures. This study examined temperature effects on nutrient removal and morphological stability of the granular and denitrifying phosphorus accumulating organisms (PAO and DPAO, respectively) using sequencing batch reactors (SBRs) at 5, 10, and 20 ℃. Lab-scale SBRs were continuously operated using anaerobic-anoxic and anaerobic-oxic cycles to develop the PAO and DPAO granules for 230 d. Sludge granulation in the two SBRs was observed after approximately 200 d. The average removal efficiency of soluble chemical oxygen demand (SCOD) and PO₄^3--P remained >90% throughout, even when the temperature dropped to 5 ℃. The average removal efficiency of NO₃^--N remained >80% consistently in DPAO SBR. However, nitrification drastically decreased at 10 ℃. Hence, the removal efficiency of NH₄⁺-N was decreased from 99.1% to 54.5% in PAO SBR. Owing to the increased oxygen penetration depth at low temperatures, the influence on nitrification rates was limited. The granule in DPAO and PAO SBR was observed to be unstable and disintegrated at 10 ℃. In conclusion, morphological characteristics showed that changed conversion rates at low temperatures in aerobic granular sludge altered both nutrient removal efficiencies and granule formation.

• Journal of Environmental Health Sciences
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• v.32 no.1 s.88
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• pp.27-35
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• 2006

This study was carried out to investigate the removal of nitrogen and phosphorus in municipal sewage depending on existence of biological coated media in BCM reactor. The reactor with biological coated media is the process combining $A_2/O$ process. The removal efficiencies for $COD_{Mn},\; BOD_5,\;SS$, T-N and T-P were $78\%,\;90.5\%,\;92.3\%,\;61.9\%,\;60.2\%$, respectively. The specific nitrification rate$(mgNO_3-N/gMLSS{\cdot}d)$ of Contact aeration basin was 52.2 and the specific denitrification rate$(mgNO_3N/gMLSS{\cdot}d)$ in anoxic basin was 95.1. Also, phosphorus release$(mgPO_4-P/gMLSS{\cdot}d)$ in Anaerobic basin was 71.8 and Phosphorus uptake$(mgPO_4-P/gMLSS{\cdot}d)$ in contact aeration was 27.1.

• Journal of the Korean Society of Safety
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• v.14 no.3
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• pp.78-83
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• 1999

This work is the experimental study for NO and NOx removal by utilizing non-thermal plasma. To apply to moving pollution source such as diesel automobile, we suggested the metal packed-helical wire reactor(MPHW) and measured properties of MPHW by varying the peak voltage, frequency, NOx concentration and flow rate for simulated NOx gas balanced with $N_2$. And then we compared these results with the results of cylinder-wire(CW) which was one of popularly used reactor in nonthermal plasma applications. The results of MPHW show fairly good NO and NOx removal rate compare with CW around above 20%. However. the power consumption of MPHW is larger than that of CW as much as around 2.5Watt in all range.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.499-502
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• 2001

In this experiment, an attempt to use the sludge pellets as catalyst for NO removal from simulated gas is experimentally investigated by using cylinder type reactor and packed-bed reactor. An experimental investigation has been conducted for NO concentration of 50[ppm], 100[ppm], 200[ppm] balanced with air, a gas flow rate of 5[1/min]. Ac voltage to discharge the gases was supplied. In the result, NOx removal rate in packed bed reactor is higher than that in cylinder type reactor. it is thought that plasma density in contact point of BaTiO$_3$ is significantly higher than that in cylinder reactor.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.553-556
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• 2000

Possibility of biological nitrogen treatment was tested in wastewaters with low C/N ratio. Chlorella kessleri was inoculated at $10^6\;cell/mL$ of initial density in two different artificial wastewaters: one that contained glucose for organic carbon source and the other without carbon source. Nitrate could be successfully reduced below 10 mg $NO_3/mL$ from initial nitrate concentration of 560 mg $NO_3/mL$ in 10 days even in the wastewater without carbon source, This 98% removal of nitrate without extra organic carbon source lights up the future of biological wastewater treatment, where the insufficient ability of nitrogen removal is a major problem.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.3
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• pp.117-125
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• 2002

This study experimented a possibility of advanced treatment through microorganism that converts $NH_3-N$ to organic nitrogen in wastewater contaminated by ammoniac nitrogen unlike conventional nitrogen removal process. After distributing three kinds of special bacteria that use $NH_3-N$ as a substrate, when those bacteria were cultured in no salt condition and salt condition (3% NaCl), M11 showed better growth in salt condition and M12 showed better growth in no salt condition. However M7l grew well in both no salt condition and salt condition. In the test of glucose effect, maximum growth and removal rate were observed in glucose concentration of 5g/L but in high concentration (1000mg/L as $NH_3-N$) of $NH_3-N$ growth and removal rate were low. Removal rate was the highest in 100mg/L $NH_3-N$ and the fact that concentration of $NO_2-N$ and $NO_3-N$ didn't increase assumed $NH_3-N$ was converted to organic nitrogen. Optimum concentration of $K_2HPO_4$ for phosphorous supply and buffer was 5g/L. Special bacteria distributed could use $NO_2-N$ and $NO_3-N$ as well as $NH_3-N$ as substrates. This study showed that when growth rate of bacteria was high removal rate also was high. It is possible to apply as a method to treat wastewater polluted by $NH_3-N$.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.1
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• pp.51-62
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• 2010

The high concentration of N in the wastewater from livestock farming generally renders the efficiency of the wastewater treatment. Therefore, removal of N in livestock wastewater is crucial for successful treatment. The current study was conducted to investigate the optimum conditions for partial nitrification under anaerobic condition following nitritation in TPAD-BNR(two-phase anaerobic digestion-biological nitrogen removal) operating system. Sequential operating test to stimulate partial nitrification in reactor showed that partial nitrification occurred at a ratio of 1.24 in $NO_2{^-}$-N:$NH_4{^+}$-N. With this result, a wide range of factors affecting stable nitritation were examined through regression analysis. In the livestock wastewater treatment procedure, the hydraulic retention time (HRT) and pH range for optimum nitrite accumulation in the reactor were 1-1.5 days and 7-8, respectively. It was appeared that accumulation of $NO_2{^-}$-N in the reactor is due to inhibition of the $NO_2{^-}$-N oxidizer by free ammonia (FA) while the effect of free nitrous acid was minimal. Nitrification was not influenced by DO concentration at a range of 2.0-3.0 mg/L and the difference in the growth rate between $NH_4{^+}$-N oxidizer and $NO_2{^-}$-N oxidizer was dependent on the temperature in the reactor.

• Archives of Plastic Surgery
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• v.34 no.2
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• pp.186-190
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• 2007

Purpose: Plate systems have been used for osteosynthesis of cranial and oromaxillofacial fracture. However, there is no consensus on the need for routine removal of plate and the question about indications of removal. Therefore, we present the retrospective study to clarify the indications and consensus of removal. Methods: The medical records of patients who were treated with rigid internal fixation using plates after craniofacial trauma were reviewed. Study variables included age, gender, type of fracture, type of plate, seniority of the operator, causes of removal, and time between insertion and removal. All results amendable to statistics were analyzed using SPSS 10.0 to determine which set of variables might affect the fate of the plates. Results: For a period of 10 years (March 1, 1994 through July 31, 2004), total of 41 plates(6.7%) were removed among 609 plates inserted into 419 patients; 27 plates were removed from 15 patients for infection, which is the most common cause of removal accounting for 65.8%. Mean time between insertion and removal is 35.2 months and mean age is 41.4 years. Most plates were removed from combined fracture(14.92%) and facial fracture(8.47%) and these were statistically significant. The age, gender, seniority of the operator and other variables were not statistically associated with plate removal. Conclusion: This retrospective study shows that routine removal does not appear to be clinically indicated due to respectively low removal rate and that the commonest indications for removal were infection.