• The KSFM Journal of Fluid Machinery
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• v.17 no.3
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• pp.41-45
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• 2014

The biological aerated filter (BAF) reactor is regarded as an effective biological wastewater treatment method. It can remove pollutants by carrier filtration and biodegradation. Due to its advantages, which include high biomass retention, tolerance to toxicity, excellent removal efficiency, and slurry separation, BAF has been widely used to remove COD, $NH_4{^+}-N$, phosphorus, and other harmful organic substances. In this study, the BAF reactor was used to remove organic contaminants of domestic wastewater of Korea at both the benchand pilot-scale. The main objectives of this study are to: (i) investigate the removal efficiency of organic contaminants (ex. COD, nitrate, phosphorus) in BAF reactors at both scales; (ii) characterize the small-scale wastewater treatment plant using the BAF reactor. The concentration of COD in the influent increased from 69 to 246 mg/L. During the operation period, the final effluent concentration of COD remained maximum 4.0 mg/L, and the average removal efficiency was above 88%. The present study investigated the removal efficiencies of COD, TN, TP and $NH_4{^+}-N$ from smelting wastewater by BAF system. When treating wastewater in both bench and pilot-scale reactors, the BAF worked well.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.3
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• pp.82-92
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• 2013

The Intermittent Aeration MBR systems have the advantage of controlling reaction time by changing aeration period and are one of economic BNR systems since these processes do not require MLSS recirculation that demands capital and operation costs. In this study, two intermittent aeration MBR systems were studied by computer simulation: an intermittent aeration MBR system that had both 1hr/1hr and 4hr/4hr aeration/unaeration periods at intermittent reactor and NEW INTERMITTENT-process that was an energy saving process and certified as a new process by Korean government. Since DO concentration reached only at 0.23mg/L at intermittent reactor when it was aerated, the Intermittent aeration MBR system having 1hr/1hr aeration/unaeration period showed simultaneous nitrification/denitrification and had the highest nitrogen and phosphorus removal efficiencies that were 57% and 55%, respectively. Since this study was based on the constant influent flow and characteristics, more studies are needed to define the operational characteristics of intermittent aeration MBR systems under dynamic influent conditions.

• 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.

• Environmental Engineering Research
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• v.20 no.4
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• pp.336-341
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• 2015

The industrial-scale biological treatment of Chinese nutgall processing wastewater was conducted with a $200m^3$ expanded granular sludge bed reactor and a $900m^3$ bio-contact oxidation reactor. The temperature of the two reactors was controlled under mesophilic conditions ($32-40^{\circ}C$), through changing the proportion of the dilution water, which was composed of steam condensation water and residual circulating water. The effluent COD, gallic acid, chroma, total nitrogen, total phosphorus levels and pH of both the expanded granular sludge bed and bio-contact oxidation reactors were monitored. In addition, the redox potential in the expanded granular sludge bed was recorded. The total COD removal efficiency was 87.257% when the influent COD concentration was $14\;251{\pm}3\;148mg/L$, and the ratio of wastewater: dilution water was 1:5. The removal efficiencies of gallic acid, chroma, total nitrogen, and total phosphorus were 72.221%, 43.940%, 64.151% and 39.316%, respectively. The effluent pH increased in either the expanded granular sludge bed reactor or the bio-contact oxidation reactor during the operation. The redox potential in the expanded granular sludge bed varied between -367 mV and -435 mV. The results indicate that the combined process was suitable for treating Chinese nutgall processing wastewater.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.657-668
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• 2014

Under Korea's Enforcement Decree of the Framework Act on Environmental Policy amended in 2013, total organic carbon (TOC) is newly added as water quality parameter to assess organic pollution in water and aquatic ecosystem. To meet the TOC requirement and improve quality of effluent discharged into public watershed, it is also necessary to develop standards for TOC in effluent from public sewage treatment works (PSTWs). In this study, we reviewed the characteristics and removal efficiency of TOC in influent and effluent of PSTWs. The study found that phosphorus treatment process removed not only soluble phosphorus but also a portion of TOC remaining after the secondary treatment process. TOC concentration in effluent from PSTWs operated in tandem with industrial wastewater treatment work was higher due to influx of insoluble substances from the industrial wastewater treatment work. In order to lay a foundation for the management of TOC from PSTWs, it is necessary to carry out research on TOC from different perspectives. For example, studies on the generation mechanism of TOC and the impact of TOC on drinking water resources, assessment of effluent qualities through monitoring, and development of measures to control TOC for the preservation of aquatic ecosystem are needed.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.231-231
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• 2020

Unlike conventional treatment technologies, the performance of nature-based facilities were susceptible to seasonal changes and climatological variabilities. This study evaluated the effects of seasonal variables on the treatment performance of constructed wetlands (CWs). Two CWs treating runoff and discharge from agricultural and livestock areas were monitored to determine the efficiency of the systems in reducing particulates, organics, and nutrients in the influent. For all four seasons, the mean effluent suspended solids concentration in the agricultural CW (ACW) increased by -2% to -39%. The occurrence of algal blooms in the system during summer and fall seasons resulted to the greatest increase in the amount of suspended materials in the overlying water. unlike ACW, the livestock CW (LCW) performed efficiently throughout the year, with mean suspended solids removal amounting to 61% to 68%. Algal blooms were still present in LCW seasonally; however, the constant inflow in the system limited the proliferation of phytoplankton through continuous flushing. The total nitrogen (TN) and total phosphorus (TP) removal efficiencies in ACW were higher during the summer (21% to 25%) and fall (8% to 21%) seasons since phytoplankton utilize nitrogen and phosphorus during the early stages of phytoplankton blooms. In the case of LCW, the most efficient reduction in TN (24%) and TP (54%) concentrations were also noted in summer, which can be attributed to the favorable environmental conditions for microbial activities. The mean removal of organics in ACW was lowest during summer season (-52% to 35%), wherein the onset of algal decay triggered a relative increase in organic matter and stimulate bacterial growth. The removal of organics in LCW was highest (54 % to 55%) during the fall and winter seasons since low water temperatures may limit the persistence of various algal species. Variations in environmental conditions due to seasonal changes can greatly affect the performance of CW systems. This study effectively established the contributory factors affecting the feasibility of utilizing CW systems for treating agricultural and livestock discharges and runoff.

• Journal of Korean Society on Water Environment
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• v.24 no.3
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• pp.306-310
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• 2008

Characteristics of microalgal growth was investigated using anaerobic effluent from two-phase animal waste digestor as substrate. Batch experiments were carried out to investigate the effect of the initial nitrogen and phosphorus concentrations on growth of Microcystis aeruginosa, Chlorella sp. and Euglena gracilis. In 400 times diluted anaerobic effluent (TN 3 mg/L), single cell growth of the Euglena gracilis population increased twice without delay, although Chlorella sp. and Microcystis aerugenos take over 144 hours. Similar appearance with single cell growth was observed in mixed cultures. However, microalgae population did not increase under condition of 10 times diluted influent (TP 3 mg/L) in both pure and mixed cultures, which was affected by high organic and nitrogen concentration. Logistic growth model successfully fitted to determine biokinetic parameters such as ${\lambda}$: lag time, ${\mu}m$: maximal specific growth rate, A: asymptote of growth.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.3
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• pp.339-349
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• 2013

Biological treatment of RO concentrate from wastewater reuse process is known to be very difficult due to its high concentration of non-degradable organics and salt ions such as chloride, nitrate and phosphate. In this research, the treatment performance of MBR was examined using RO concentrate mixed with raw wastewater as the influent of MBR. Addition of PAC (powdered activated carbon) to MBR was also evaluated in order to enhance the treatment performance and stability. The performance of MBR for treating only RO concentrate decreased gradually although external carbon source was added. The average removal performance of MBR with and without PAC decreased from 99.1 %(98.8 %) to 94.9 %(91.4 %) for COD, 81.3 %(80.3 %) to 42.0 %(41.9 %) for T-N and 57.3(55.0 %) to 30.0 %(21.0 %) for T-P with the increase of RO concentrate mixing rate of 0 % to 20 % in the feed water. Addition of PAC showed positive effect on the performance of MBR for the removal of COD and phosphorus in case that the ratio of RO concentrate to feed water increased.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.705-714
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• 2008

Three Mesh Screenning Reactors (MSRs) were operated in three different modes to investigate the effect of the mesh opening size and the filtrate flux on the removal of particulate matters and the production of soluble organic matters. The mesh opening size was $82{\mu}m$ (Mode 1), $61{\mu}m$ (Mode 2) and $38{\mu}m$ (Mode 3), respectively, and each mode has three different filtrate flux; $0.47m^3/m^2/d$, $0.95m^3/m^2/d$ and $1.42m^3/m^2/d$, respectively. TSS removal efficiency of mode 1, 2, and 3 fed with 191 mgTSS/L was 27%, 36%, and 60%, respectively. The SCOD concentration of 91mg/L in influent for the mode 1, 2, and 3 increased to 117 mg/L, 127 mg/L, and 155 mg/L, respectively. For the all MSRs, there was no significant effect of filtrate flux on the removal of particulate matters and the production of soluble organic matters. However, the mesh opening size greatly affected the removal of particulate matters and the production of soluble organic matters in wastewater. Three parallel A2O processes consisting of anaerobic, anoxic and aerobic reactors maintaining mixed liquor suspended solids (MLSS) of 3,000 mg/L were operated to investigate the effectiveness of MSR on the removal efficiencies of the organic matters, nitrogen, and phosphorus; MSR influent was introduced to System 1 (183 mgTSS/L, 324 mgTCOD/L, 87 mgSCOD/L, 45.2 mgTKN/L, and 6.6 mgTP/L) and MSR efluent was introduced to System 2 and 3(72 mgTSS/L, 289 mgTCOD/L, 141 mgSCOD/L, 40.2 mgTKN/L, and 4.2 mgTP/L). HRTs of the anaerobic reactors in systems 1, 2 and 3 were 1 h, 1 h and 0.6 h, respectively and anoxic reactors were 2 h in all systems. HRTs of the aerobic reactors in systems 1, 2 and 3 were 5 h, 3 h and 3 h, respectively. TSS concentration in effluent of both system 2 and 3 is about 8 mg/L and lower than that of system 1 effluent. Despite higher TCOD loading and SCOD loading, both Systems 2 and 3 had a greater TCOD and SCOD removal efficiency at 91% and 92% than System 1 was at 88% and 82%, respectively. The nitrification efficiency for system 2 was greater than observed for System 1 (99% verses 97%). The denitrification efficiency for systems 1, 2 and 3 was 78%, 88% and 87%, respectively. System 2 and 3 showed about 12% higher TN removal efficiency than system 1 (85% verses 73%). The effluent TP concentration for system 2 was less than observed for system 1 and 3.

• Journal of Wetlands Research
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• v.17 no.2
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• pp.203-208
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• 2015

To identify the effect of fallen cherry blossom on the artificial pond ecosystem, microcosm experiment was conducted into the aquatic decomposition of Prunus species petals. Petals were put in $1mm^2$ mesh nylon litter bags. For treatment group, one flower litter bag was placed into each pot microcosm ($27{\times}20{\times}8cm^3$) filled with influent water from the artificial pond, whereas control group microcosm contained pond water only. Decomposition time were set differently (4, 8, 12, 16 days) among treatment groups. At the end of experiment, most petals were decomposed and only 32.3% of initial dry weight remained with the decay rate (k) of $7.06{\times}10^{-2}day^{-1}$. $NO_3-N$ concentration of microcosm water decreased sharply from 1.90 mg/L at first to 0.02 mg/L, whereas $NH_4-N$ concentration increased from 0.03 mg/L to 2.85 mg/L continually. $PO_4-P$ concentration was 0.03 mg/L at first and increased to 2.39 mg/L by decomposition. Therefore, available phosphorus seems to have leached with higher rate than nitrogen from the petals litter. Increase about 0.02 mg/L in $PO_4-P$ concentration could be estimated in artificial pond from the calculation on the total quantity of fallen blossoms. This result suggests that available phosphorus from the decomposed Prunus petals could cause eutrophication in the artificial pond.