• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.3
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• pp.97-106
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• 2006

The pollutant concentrations at experimental paddy plots with three (excessive, standard, reduced) different fertilization rates were investigated during 2001-2002 irrigation seasons. Mean concentrations of pollutants in ponded water were not significantly different among three experimental plots, but the T-N concentrations in percolated water significantly depended on fertilization rates. The T-N, T-P and $COD_{Cr}$, concentrations in ponded water during early irrigation season (late May to mid-June) were much higher than those during later irrigation season likely due to fertilization and low uptake by young rice crops. The T-N concentrations decreased but the concentrations of T-P and $COD_{Cr}$, increased three days after tillering fertilization. The removal rates of T-N by paddy plots were $0.13-0.16g/m^2{\cdot}d$ for an excessive fertilization plot, $0.08-0.25g/m^2{\cdot}d$ for a standard fertilization plot, and $0.03-0.34g/m^2{\cdot}d$ for a reduced fertilization plot three days after tillering fertilization. On the other hand, T-P and $COD_{Cr}$, were released three days after tillering fertilization.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.7 no.4
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• pp.279-284
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• 2007

Nowadays, due to development of automatic control devices and various sensors, one operator can freely handle several remote plants and processes. Automatic diagnosis and warning systems have been adopted in various fields, in order to prepare an operator's absence for patrolling plants. In this paper, a Bayesian networks based on-line diagnosis system is proposed for a wastewater treatment process. Especially, the suggested system is included learning structure, which can continuosly update conditional probabilities in the networks. To evaluate performance of proposed model, we made a lab-scale five-stage step-feed enhanced biological phosphorous removal process plant and applied on-line diagnosis system to this plant in the summer.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.657-662
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• 1999

This study was conducted for the purpose of assessing the pollutant removal possibilities of sedimentation pool formed by deep dredging of a reservir inlet. Water quality data were collected in the Masan reservoir, whose inlet has been dredged deep like sedimentation pool. The average concentration of chemical oxygen demand(COD), total nitrogen(T-N) adnd total phosphorous(T-P) in the deep dredged area were 8.3∼28.4mg/$\ell$ (COD), 2.0∼6.0mg/$\ell$(T-N), 0.17∼1.34mg/$\ell$(T-P), which were 3.3% (COD) , 30.6%(T-N) and 46.4%(T-P) higher than those of middle part of the reservoir. From these results, it was considered the deep dredged area in the inlet of reservoir might play a key role to improve reservoir water quality.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.4
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• pp.56-63
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• 2001

This paper presents treatment efficiency and plant growth of a subsurface-flow constructed wetland system (23 m in length, 6.5 m in width, 0.65 m in depth) over one year after its establishment on floodplain of a stream in June 2000. An upper layer of 10 cm in depth was filled with course sand and the main biological layer of 50 cm depth with crushed stone with 8 - 15 mm in diameter. The system was planted with common reeds (Phragmites australis) grown on pots. Effluent discharged from a secondary-level treatment plant was funneled into it. Reed stems emerging in April 2001 grew up to 145.9cm until July 2001. The number of reed stems in July 2001 increased by about 11 times compared with that just after planting. The system was inundated seven times by storms over the monitoring period. Reeds were slightly bent after flooding, however they returned to almost upright standing in a couple of weeks. Small portion of inside slope of berm was eroded and the system surface had a sedimentation of 2 - 3 mm in depth. The average removal rates for SS, $BOD_5$, T-N and T-P was 73%, 70%, 53%, and 72%, respectively. The purification efficiencies for SS and $BOD_5$ were fairly good. The reduction rates for T-N was relatively low for the period of late fall through winter until early spring due to lower water temperature which retarded microbial nitrification and denitrification mechanisms. Reduction in the concentration of T-P during fall and winter was relatively higher than that during spring. Leach of phosphorous from plant litters lying on system surface and slight resuspension of precipitated phosphorous in substrates resulted in lower reduction for T-P in spring.

• Journal of Korean Society on Water Environment
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• v.33 no.6
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• pp.670-679
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• 2017

An experiment to study the effect of temperature, light, and dredging on release of nutrients downstream from Gongjicheon in the Uiam reservoir was carried out in the laboratory using sediments from different depths. At various water temperatures, dissolved total nitrogen was not released, but the average nutrient flux of dissolved total phosphorus was increased (0.034 at $15^{\circ}C$, 0.005 at $20^{\circ}C$, 0.154 at $25^{\circ}C$, $0.592mg/m^2/d$ at $30^{\circ}C$). Dissolved total phosphorous was released in controlled darkness. In contrast, in controlled light, the concentrations of dissolved total phosphorous and dissolved total nitrogen in the overlying water steadily decreased during the study period (70 d), because they were continuously consumed by the growth of photosynthetic algae. However, there was no significant relationship between water nutrient concentration, nutrient release, and the depth of the sediment. We concluded that the dredging of sediment would not affect the nutrient release rate of the sediment, because there were no significant differences in the nutrient concentrations released from the sediment. When the sediment was removed from the surface to 20 cm in depth, the nutrients were not transferred to the water body, implying that the sediment removal had little effect on secondary pollution.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.96-102
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• 2014

To meet the reinforced discharge standards, effect of coagulant PAC (Poly aluminium chloride, 10.4% as $Al_2O_3$) on phosphorous removal in advanced wastewater treatment process (a modified $A^2$/O). 15 mg/L of PAC determined by jar-test was added to influent of settling basin in a modified $A^2$/O consists of anaerobic, anoxic, and oxic chamber which contains Bio-clod and porous polyurethane media. Performance of PAC was tested by supernatant after settling. The removal efficiencies of BOD, COD, TP (total phosphorus) and SP (soluble phosphorus) on biological process with PAC were 96.1%, 88.8%, 97.0% and 98.6%, compared with those on biological process without PAC were 95.4%, 72.4%, 71.6% and 59.5% respectively. 18.4% of TP and 39.1% of SP removal efficiency was increased, although increase of BOD and COD removal rate was not significant. Only PAC addition to influent of settling basin in $A^2O$ process can help total phosphorus removal to 0.13 mg/L with following discharge standard.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.109-113
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• 1998

The clay and yellow loess have capability to adsorb and precipitate particles. The removal efficiencyes of those flocculents on the dinoflagellate, Cochlodinium polykrikoides, have been studied in laboratory and in field near Tongyong fish farm in September, 1996. The removal efficiencyes in the laboratory experiment was $43\%$ for $2\;g/{\ell}$, $64\%$ for $6g/{\ell}$ and $88\%$ for $10\;g/{\ell}$ in one hour after dispersion. No big difference of removal efficiency was found between the raw and the acid-activated loess. In the field survey, the removal rates ranged from 72 to $80\%$ in 30 min after the dispersion. The effect of loess scattering on water quality was estimated. The concentrations of dissolved inorganic nitrogen (DIN), chemical of gen demand (COD) and chlorophyll a decreased more or less after dispersion, while the concentration of suspended solid (SS) increased. The concentrations of dissolved oxygen (DO) and dissolved inorganic phosphorous (DIP) were kept constant. These results indicated that the dispersion concentration of more than $10g/{\ell}$ has a good removal efficiency of above $80\%$ without big variation of water quality after dispersion of yellow loess.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.5
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• pp.323-334
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• 2021

Pilot-scale coagulation and sedimentation processes were operated to investigate the T-P (Total phosphorus) removal efficiency. A multiple regression model was also derived to predict the water quality improvement effect with river water characteristics. The inflow rates for the pilot-scale facility were 157-576 m³/day, and the coagulant doses were in the range of 13.7-58.5 mg/L (average 38.9 mg/L) for PAC (Poly alum chloride) and 16.5-62.1 mg/L (average 36.0 mg/L) for alum. The results found that the influent BOD (Biochemical oxygen demand) and T-P concentrations were 4.9 mg/L and 0.115 mg/L, and the removal efficiencies were 52.7% and 59.4%, respectively. T-P removal efficiencies on wet weather days were higher by 10% than dry weather days because influent solids influenced T-P's coagulation process. The pH of river water was 6.9-7.8, and the average pH was 7.3. Although the pH variation was not significant, the trend showed that the treatment efficiency of T-P and PO₄-P removal increased. Thus, the pH range considered in this study seems to be appropriate for the coagulation process, which is essential for phosphorous removal. The T-P removal efficiencies were 19.6-93.3% (average 59.2%) for PAC and 16.4-98.5%(average 55.9%) for alum; thus, both coagulants showed similar results. Furthermore, the average coagulant doses were similar at 42.4 mg/L for PAC and 41.3 mg/L for alum. When the T-P concentration of the effluent was compared by the [Al]/[P] ratio, the phosphorus concentration of the treated water decreased with an increasing [Al]/[P] ratio, and the lowest T-P concentration range appeared at the [Al]/[P] ratio of 10-30. A seasonal multiple regression analysis equations were derived from the relationships between 10 independent and dependent variables (T-P concentration of effluent). This study could help lake water quality maintenance, reduce eutrophication, and improve direction settings for urban planning, especially plans related to developing waterfront cities.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.470-479
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• 2004

The experimental conditions and relationships between parameters such as organic matter, aeration volume, aeration time, and precipitation time for the effective treatment of domestic wastewater were investigated. With the batch systems, the adsorption amount of unit microbe was measured with the change of MLSS concentration, precipitation time, and aeration amount. Theoretical adsorption amount of microbes was then numerically formulated by use of a SPSS multiple analysis as follows: $$Y=-0.0106(X_1)+0.07310(X_2)+42.705(X_3)+62.700$$ In this study, the amount of organisms to be removed in the range of MLSS concentration 2,000~4,500 mg/l were examined. In order to investigate the optimal condition of nitrification, the upper water in the biosorption stage was used as the initial experiment water. The results showed that the C/N ratio was 1.5 and the reaction time for the optimal nitrification was 1.5 hr. When the adsorption efficiency for microbe biosorption was 66%, the optimum denitrification efficiency was 83.3%. When the optimum parameters obtained from the batch experiment were applied to the lab-scale operation, the total retention time from the flow-in to flow-out was 10 hours and the removal efficiency was 93.8% for $COD_{cr}$ and 80.9% for TN. For the full-scale operation, the total retention time was 9.0 hours and the removal efficiency was 94.4% for BOD, 89.6% for $COD_{cr}$, 88.0% for TN, and 86.2% for TP.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.1
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• pp.89-99
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• 2006

The growth and biomass of reeds(Phragmites australis) growing in a subsurface treatment wetland system were investigated from April 2003 to October 2003. Nitrogen(N) and phosphorous(P) concentrations in above-ground(AG) and below-ground(BG) tissues of reeds were examined and the removal rate of N and P by reeds were analyzed. The system, 29 m in length, 9 m in width and 0.65 m in depth, was constructed in June 2001 on a floodplain in the down reach of the Kwangju Stream in Korea in order to purify polluted water of the stream. A bottom layer of 45 cm in depth was filled with crushed granites(15~30 mm in diameter) and a middle layer of 10 cm in depth was filled with pea pebbles(10 mm in diameter). An upper layer of 5 cm contained course sand. Reeds were transplanted on the surface of the system, which were dug out of natural wetlands, and their shoots were trimmed 40 cm in height. The height and density of the shoots averaged 237.7 cm and 244.0 shoot/$m^2$, respectively, when the reeds grew fully. The maximum biomass of AG and BG tissues were 1,964 and 1,577 g/$m^2$, respectively, and the AG : BG ratio of biomass was 1.26. Mean AG and BG dry weights were recorded as 1,355 and 748 g/$m^2$, respectively. The AG and BG tissue concentrations of N averaged 12.37 and 10.01 mg/g, respectively, and those of P 2.37 and 2.03 mg/g, respectively. Inflow to the system averaged 40 $m^3$/day. The concentrations of total nitrogen(T-N) in influent and effluent were 8.4 mg/L and 3.2 mg/L, respectively, and those of total phosphorous(T-P) were 0.73 and 0.38 mg/L, respectively. The total removal of T-N and T-P by the system during the investigation period averaged 140.2 and 9.7 g/$m^2$, respectively, and the total uptake of N and P by the reeds were calculated as 24.39 and 4.73 g/$m^2$, respectively. Average removals of about 17% of N and about 49% of P by reeds were recorded. The N and P concentrations in AG tissues were significantly different among the three zones of the system:near to inflow(St1), in the middle of system(St2), and near to outflow(St3). The N and P concentrations in BG tissues were also significantly different among St1, St2 and St3. N and P concentrations in AG and BG tissues of reeds growing in St1 were higher than those in St2 and St3. The height and density of shoots of reeds in St1 were larger than those in St2 and St3. Significant amounts of N and P in the influent were taken up by reeds in St1.