• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.4
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• pp.96-105
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• 2000

Field experiment was performed from August 1996 to December 1999 to examine the performance of constructed wetland system for wastewater treatment in rural area. The constructed wetland system was installed in Konkuk University and the effluent from septic tank of school building was used as an influent to the treatment basin. The treatment basin was composed of sand bed with planted reed. From August 1996 to June 1998 the hydraulic loading rate was fixed with about 15.63cm/day and theoretical detention time was 1.38 days, and from July 1998 to December 1999 the hydraulic loading rate was about 6.25cm/day and theoretical detention time was 3.5days. It worked continuously even during winter time, and the sewage flowed without freezing even when average daily air temperature was below -1$0^{\circ}C$. Average removal rate of BOD , COD, and SS was about 70%, T-P removal rate was about 50.8% , and T-N removal rate was 23.9%. The reason for poor T-N removal might be due to high influent concentration and short retention times. At the later years BOD and COD removal rates were increased , and SS and T-P removal rates did not change significantly , but T-N removal rates were decreased. The effluent of the wetland system often effluent water quality standards for sewage treatment plant, therefore, further treatment would be required if the effluent need to be discharged to the public water. Wetland system involves relatively large land area and could be suitable for rural area. Therefore, utilization of reclaimed sewage for agricultural purpose or subsequent land treatment is recommended as a ultimate disposal of sewage for agricultural purpose or subsequent land treatment is recommended as a ultimate disposal of sewage in rural area.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.1
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• pp.84-93
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• 2004

This study was performed : 1) to find the suitable HRT(hydralic retention time), 2) to evaluate the effects of the ratio of mixing/aeration time and injection time of external carbon source, for the removal of organics, nitrogen and phosphorus in swine wastewater by SBR(sequencing batch reactor process), which is one of the biological treatment process. The result of this study were summarized as follows : (1) As the ratio of mixing/aeration time was higher, $NH_4{^+}-N$ removal efficiency was increased and it was increased with increasing injection time of external carbon source because nitrification was affected by denitrification microbes propagation when injection time of external carbon soruce was shorted. T-N removal efficiency was increased with increasing the ratio of mixing/aeration time and injection time of external carbon source. (2) The T-P removal efficiency showed a great difference in each operating condition, and it was increased with increasing the ratio of mixing/aeration time increased and when the injection time of external carbon source was shorted because denitrification was done with effect by denitrification microbes propagation. (3) The highest removal efficiency of organic and nitrogen were obtained by the operating condition of Run 4-1(the ratio of mixing/aeration time : 16.5/5.5, injection time of external carbon source : 15hours) and T-P were obtained by the operation condition of Run 4-2(the ratio of mixing/aeration time : 16.5/5.5, injection time of external carbon source : 3hours), and efficiency(effluent concentration)of $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, T-N and T-P in the treated water was 96.1%, 87.7%, 90.6%, 86.6% and 84.5%, respectively.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1261-1265
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• 2002

This study was focused on the investigation of the characteristics of organics and nitrogen removal with the recycle ratio in anoxic/oxic(A/O) packed bed process that consisted of the anoxic reactor and the aerobic reactor. As increasing the recycle ratio by 0.5, 1.0, 2.0, the COD removal efficiency increased by 94.0%, 98.5%, 98.8% respectively. The aerobic reactor showed the perfect nitrification efficiency by 98.5%, 99.2%, 98.0% respectively. The T-N removal efficiency with the recycle ratio, increased by 56%, 67%, 70% respectively. As increasing the recycle ratio by 0.5, 1.0, 2.0, T-P removal efficiency decreased by 62.1%, 57.4%, 51.3% respectively. The process by releasing the stored phosphorus in the anoxic reactor and uptaking the excess phosphorus in the aerobic reactor, occurred well comparatively when recycle ratio is 0.5. But this process did not occur when the recycle ratio is 1.0 and 2.0. And optimum pH of nitrification was about 6~7 and alkalinity decreased as nitrification rate increased. As increasing the recycle ratio in the anoxic reactor, DO concentration and ORP increased.

• KSBB Journal
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• v.18 no.3
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• pp.234-238
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• 2003

Biofilm process is preferred to activated sludge process in small domestic wastewater treatment plant because of its simplicity in operation and maintenance. Column reactor filled with waste ceramics and with waste plastics was used to remove pollutants in restaurant wastewater. COD removal at 18 hours of hydraulic retention time (HRT) gave 93.7%, COD removal during the experimental period, where maximum COD removal was observed. Under same condition, average removal of total nitrogen and total phosphorus were 82.3% and 25.9%, respectively Organic and nitrogen were efficiently removed with the HRT of 18 hours or more.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.165-169
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• 2008

It has been reported that most wastewater treatment plants have difficulties in nitrogen removal during winter season due to declined activity of nitrifiers in the condition of low temperature. This study was conducted in order to find out optimum operating condition for efficient nitrogen removal in low temperature. A series of operating conditions with various HRTs of each tank were simulated using the GPS-X program. The optimum HRT combination for effective nitrogen removal was 0.3 hr/0.5 hr/1.36 hr/4.84 hr(PreAx/An/Ax/Ox) with 51.4% of T-N removal efficiency and 57.3% of $NH_4^+$-N removal efficiency.

• Journal of Environmental Health Sciences
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• v.27 no.1
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• pp.93-99
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• 2001

This study aims at finding out pertinent reaction conditions for treating high concentration ammonia contained in N-chemical factory wastewater with decompressed ammonia stripping method that was designed. And it also tries to investigate adsorption capability of removed ammonia to soil. The results from experiments are as follows ; 1. The removal rate of N $H_3$-N of synthetic wastewater was under 85% at pH 10 with decompressed ammonia stripping method. The reaction time in pressure 360 mmHg at pH 11 and 12 was shorter than in 460 mmHg, and the removal rate of N $H_3$-N with decompressed ammonia stripping method at 9$0^{\circ}C$ was 11~15% higher than air stripping 2. The optimum conditions for decompressed ammonia stripping with synthetic sample were shown as pH 12, temperature 9$0^{\circ}C$, internal reaction pressure 460 mmHg and reaction time 50 minutes. These conditions were applied to treat the wastewater containing organic-N 290.5mg/$\ell$, N $H_3$-N 168.9mg/$\ell$, N $O_2$-N 23.2mg/$\ell$, N $O_3$-N 252.4mg/$\ell$, T-N 735mg/$\ell$. Organic-N turned out to be removed 60%, the removal rate of N $H_3$-N IS 94%, T-N is 50%. But N $O_2$-N and N $O_3$-N were increased with 7.8% and 14.9% respectively. 3. The CO $D_{Sr}$ removal rate in decompressed ammonia stripping reaction was 42% and S $O_4$$^{2-}$ was removed 8.2%. It was turned out caused with higher pH and thermolysis. 4. In soil adsorption of ammonia desorbed from the decompressed stripping process of wastewater, the recovery rate was 76% in wet soil.

• KSBB Journal
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• v.14 no.5
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• pp.606-610
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• 1999

The purpose of this study was to develop and evaluate rotating biological activated carbon(RBAC) process for nitrogen and phosphorus removal with increasing loading rate. The removal efficiency of $NH_4^+$-N was observed to be higher than 96.5% at all runs, and the relative stable levels of effluent $NH_4^+$-N, $NO_2^-$-N, $NO_3^-$-N could be maintained. The removal efficiency of T-N was observed to be higher than 90%, except RUN 1. The T-P removal efficiency was kept between 32.7% and 49.8%, and the amount of biomass was kept between 269 mg/g support and 473 mg/g support with varying loading rate.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.6
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• pp.41-48
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• 2003

Nitrogen removal rate and emergent plant growth were investigated of a free-water-surface constructed treatment wetland system, whose dimensions were 31m in length and 12m in width. The system was constructed on floodplain in the Kwangju Stream from May to June 2001. Cattails(Typha angustifolia) were transplanted from natural wetlands and their stems were cut at about 40cm height from their bottom ends. Water of the Kwangju Stream were funneled into the system by gravity flow and its treated effluent was discharged back into the stream. The average height of the cattail stems was 45.2cm in July 2001 and 186cm in October 2001. The number of stems averaged 22 stems/$m^2$ in July 2001 and 52 stems/$m^2$ in September 2001. Volume and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Inflow and outflow averaged 40.01 and 39.55 $m^3$/day, respectively. Hydraulic detention time was about 1.5 days. Average nitrogen uptake by cattails was 69.31 $N\;mg\;m^{-2}\;day^{-1}$. Removal rate of $NO_3-N$, $NH_3-N$ and T-N averaged 195.58, 53.65 and 628.44 $mg\;m^{-2}\;day^{-1}$, respectively. The average removal rate of T-N was about 39%.

• Journal of Environmental Science International
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• v.27 no.1
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• pp.39-45
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• 2018

In this study, the International Maritime Organization (IMO)'s guideline MEPC. 277 (64) was developed and evaluated for the removal efficiency of T-N in a SBR and MBR combined process. This combined process of resized equipment based on large capacity water treatment device for a protection of marine aquatic life. In this experiment, T-N concentration of influent and effluent was measured through with the artificial wastewater. The SBR reactor operation time was varied according to the C : N : P ratios so that different conditions for mixing and aeration period in mins (90 : 60, 80 : 40, 70 : 50) and two C: N: P ratios (10 : 5 : 3, 10 : 3 : 1) were used. During experiment in the reactor's aeration and anoxic tank DO concentrations were 3 mg/L and 0.2 mg/L respectively. Furthermore, in the reactor MLSS concentration was 2000 mg/L and flowrate was 2 L/hr. Experiment results showed that C : N : P, 10 : 3 : 1 ratio with 90 mins mixing and 60 mins aeration maximized removal efficiency at 97.3% T-N as compared to other conditions. The application of the SBR and MBR combined process showed efficient results.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.3
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• pp.234-240
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• 2010

The effectiveness of adding powdered zeolite and granular activated carbon (GAC) before starvation into biological reactor for recovering its performances was investigated. Two types of carrier addition in Sequencing Batch Reactor (SBR) system for non-saline and saline wastewater were evaluated after starvation periods. During the experiment, settleablity (SVI), floc size, fractal dimension, $COD_{Mn}$, T-N, T-P removal efficiencies and recovery time were monitored. When the wastewater feeding was resumed after starvation period for 5days, the SVI increased at the beginning of resumption and then decreased with time in both types. And the larger the floc size and fractal dimension of floc, the more increased removal efficiency for $COD_{Mn}$, T-N and T-P was also. Its performance recovery was strongly correlated with floc size and fractal dimension of activated sludge. After resuming the wastewater feeding, the SVI, floc size, fractal dimension, $COD_{Mn}$, T-N, T-P removal efficiency of SBR with carrier improved and reached its initial value faster compared to those of SBR without carrier.