• Journal of Navigation and Port Research
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• v.34 no.5
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• pp.375-381
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• 2010

This study was carried out for advanced treatment development on shipboard sewage. We employed SBR process using Bacillus sp. to remove Organic compounds, Nitrogen and Phosphorus simultaneously. Based on Res. MEPC.159(55) the system was qualified. From the results it was suggested that SBR system might be suitable process for shipboard sewage treatment in terms of pollutant removal efficiency, maintenance and special environmental conditions of ship. More than 90% of COD and BOD were removed. In addition, aover 50% of T-N and T-P were reduced.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.16-22
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• 2012

Alum contained dominantly the monomeric aluminum species, and PAC contained the polymeric aluminum species. Both Alum and PAC has been improved removal of TP with increasing coagulant dose. Coagulant used directly influenced the microbial activity. Impact on microbial activity, the PAC was smaller than Alum. And impact on microbial activity and population according to the return sludge appeared to be minor.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.57-65
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• 2019

This study assessed the contribution of emergent vegetation (Phragmites australis, Typha latifolia, and Nelumbo nucifera) to the submerged surface area, the amount of biofilms attached to the submerged portions of the plants, and the treatment performance of a free water surface (FWS) constructed wetland. Results showed that a 1% increase ($31m^2$) in the vegetative area resulted in an increase of $220m^2$ of submerged surface area, and 0.48 kg Volatile Suspended Solids (VSS) of attached biofilm. As the vegetation coverage increased, effluent organic matter and total Kjeldahl nitrogen decreased. Conversely, a higher nitrate concentration was found in the effluent as a result of increased nitrification and incomplete denitrification, which was limited by the availability of a carbon source. In addition, a larger vegetation coverage resulted in a higher phosphorus in the effluent, most likely released from senescent biofilms and sediments, which resulted from the partial suppression of algal growth. Based on the results, it was recommended that constructed wetlands should be operated with a vegetation coverage of just under 50% to maximize pollutant removal.

• Journal of Environmental Science International
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• v.31 no.4
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• pp.295-309
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• 2022

The purpose of this study was to evaluate the operational characteristics of wastewater treatment using Sequencing Batch Reactor (SBR) with Aerobic Granular Sludge (AGS) separator in the pilot plant. Pilot plant experiments were conducted using SBR with AGS separator and pollution removal efficiencies were evaluated based on the operational condition and surface properties of AGS. The results of the operation on water quality of the effluent showed that the average concentration of total organic carbon, suspended solids, nitrogen, and phosphorus was 6.89 mg/L, 7.33 mg/L, 7.33 mg/L, and 0.2 mg/L, respectively. All these concentrations complied the effluent standard in Korea. The concentration of mixed liquor suspended solid (MLSS) fluctuated, but the AGS/MLSS ratio was constant at 86.5±1.3%. Although the AGS/MLSS ratio was constant, sludge volume index improved. These results suggested that the particle discharged fine sludge and increased the AGS praticle size in the AGS. Optical microscopy revealed the presence of dense AGS at the end of the operation, and particles of > 0.6 mm were found. Compared to those of belt-type AGS separator, the required area and power consumption of the hydrocyclone-type AGS separator were reduced by 27.5% and 83.8%, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.1
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• pp.47-58
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• 2002

Much of the plastic film house soils in the southern part of the Korean peninsula are managed using a upland-paddy rotation culture system (hereafter, RS) to prevent salt accumulation in soil. However, information on the effects of RS on soil properties and environmental conservation is limited. In order to determine the effects of RS on soil properties, 22 fields under RS and 20 fields under a non-rotation system (hereafter, NRS) in plastic film houses were selected in Chinju, in southern Korea, and the P distribution characteristics were investigated, including the chemical properties. The RS contributed to the removal of water-soluble salts in the surface layer and to the redistribution of organic matter evenly in the soil profile. In the AP horizon, available phosphorus levels were $1,611mg\;kg^{-1}$ in RS and $1,789mg\;kg^{-1}$ in NRS, which markedly exceeds the optimum range for plant cultivation. Total P was lower in RS (average $4,593mg\;kg^{-1}$) than in NRS (average $5,440mg\;kg^{-1}$) and this decrease was taken to be an effect of RS. Inorganic P was the predominant form of P in both systems, followed by organic P and residual P. A soil profile showed that total and inorganic P concentrations decreased with depth in both systems. However, organic P increased withdepth in RS, which was in contrast to that noted in NRS. The increase in organic P with depth in RS implied that organically rather than inorganically derived phosphate moved through the soil. The concentrations of water-soluble P, Ca-P and Al-P were higher in NRS than in RS soil profiles, but the Fe-P concentration was higher in RS than in NRS, which might be affected by the anaerobic conditions found in paddy soils. In both systems, the Al-P form of extractable P predominated in the surface layer, followed by Ca-P, Fe-P and water-soluble P. With increasing depth, the composition rate of Ca-P to extractable P decreased to less than 10% in the 60-70cm depth, as Fe-P dominated at this level. The content of water-soluble P, potentially the main source of eutrophication, was higher in NRS than in RS. These results indicated that the RS used in plastic film houses contributed to the removal of water-soluble salts but only slightly decreased the phosphate concentration.

• Journal of Wetlands Research
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• v.16 no.3
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• pp.431-440
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• 2014

To propose the improvement and management plans to strengthen the pollutant removal efficiency of dam reservoir's constructed wetlands(CWs), the operation status and configuration of CWs (including water depth, operational flow, water flow distribution, residence time, and pollutant removal efficiency, aspect ratio, open water/vegetation ratio etc.) were analyzed in 10 major wetlands constructed in dam reservoirs. The pollutant concentrations in the inflows of the studied CWs were lower than those of American and European constructed wetlands. Especially, organic matter concentrations in all of inflows were below 3 mg/L(as BOD) due to advanced treatment of sewage disposal plant and an intake of low concentration water during dry and normal seasons. The average removal efficiency of total nitrogen(TN) and total phosphorus(TP) for 10 CWs ranged from 7.6~67.6%(mean 24.9%) and -4.9~74.5%(mean 23.7%), respectively, showing high in wetlands treating municipal wastewater. On the other hand, the removal efficiency of BOD was generally low or negative with ranging from -133.3 to 41.7%. From the analysis of the operation status and configuration of CWs, it is suggested that the low removal efficiency of dam reservoir's CWs were caused by both structural (inappropriate aspect ratio, excessive open water area) and operational (neglecting water-level management, lack of facilities and operation for first flush treatment, lake of monitoring during rainy events) problems. Therefore, to enable to play a role as a reduction facility of non-point source(NPS) pollutants, an appropriate design and operation manuals for dam reservoir's CW is urgently needed. In addition, the monitoring during rainy events, when NPS runoff occur, must be included in operation manual of CW, and then the data obtained from the monitoring is considered in estimation of the pollutant removal efficiency by dam reservoir's CW.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.8
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• pp.549-556
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• 2012

T-P removal efficiency was analyzed according to the metal to initial T-P ratio (mole basis) with respect to the samples from different WWTPs having various initial T-P and SS conditions. Also, operating costs were calculated based on the injected coagulant amount and the amount of sludge production. Most experiments were conducted by the standard jar-test protocol. Molar ratio of coagulant dose was varied considerably according to the initial SS concentration range in secondary clarifier effluent samples which had above 0.5 mg/L of initial T-P. Based on 90% T-P removal efficiency, results were: At the initial SS range of below 10 mg/L, Alum (8%) = 11 mol Al/mol P needed and PAC (17%) = 9.6 mol Al/mol P needed; At the initial SS range of above 10 mg/L, Alum (8%) = 3.9 mol Al/mol P needed and PAC (17%) = 3.2 mol Al/mol P needed.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.895-905
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• 2000

This study was performed to investigate the removal efficiencies of pollutants at various filtration rates and the quality of the filtered water along the depth of filter media during treatment of a BNR process effluent by a dual-media gravitational rapid filtration. The results of the experiments at filtration rates of 200, 300 and 400 m/day using the effluent of a pilot scale 4-stage BNR plant showed that turbidity of the filtered water was below 2.6 NTU, satisfying the Korean standard for water for reuse. Even though the SS removal efficiency deteriorated as the filtration rate increased, the average SS concentration of the filtered water was 1.3 mg/L at all filtration rates. Simultaneous biological nitrification and denitrification was observed with nitrification efficiencies of 17.4, 18.8 and 14.3%, and denitrification efficiencies of 32.3, 27.7 and 21.4% respectively at filtration rates of 200, 300 and 400 m/day. At the latter period of each filtration cycle, the effluent T-P concentration was higher than influent T-P concentration by 6.1 to 21.4% due to phosphorous release under DO-deficient condition.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.325-331
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• 2007

This study was aimed to find out methods for preventing scale formation from the struvite treated water, and improving ammonium nitrogen removal efficiency in the application of struvite crystallization for ammonium fluoride wastewater wastement. During the struvite mystallization seeding effects varied with G.td value applied as mixing conditions in the experiment. The removal efficiency of ammonium nitrogen$(NH_4^+-N)$ and phosphorus$(PO_4^{3-}-P)$ increased over 90% in the condition of low $G{\cdot}t_d$ value. In the experiment with seeding, $G{\cdot}t_d$ value was shown to decease four times lower than the one without seeding. When adding over 2% seeding materials in the total water volume, ammonium nitrogen removal efficiencies gradually increased, of which observation was also revealed in a paired-sample T-test with 95% reliability.

• Korean Journal of Environmental Agriculture
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• v.33 no.2
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• pp.111-120
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• 2014

BACKGROUND: This study was conducted to investigate the levels of pesticide residues in fruits and to assess their risk to human health. METHODS AND RESULTS: Monitoring of 215 samples of fruits collected from local markets in incheon during 2013 was performed. 259 pesticides were analyzed by multi-residue method and Quick, Easy, Cheap, Effective, Rugged, and safe/Mass/Mass(QuEChERS/MS/MS) method using Gas Chromatography-Electron Capture Detector/Nitrogen Phosphorus Detector(GC-ECD/NPD), GC-MS, LC(Liquid Chromatography-Mass/Mass(LC-MS/MS) and High Performance Liquid Chromatography-Photodiode Array/Fluorescence Detector(HPLC-PDA/FLD). In 56.3% of the samples detected pesticide residues and were not found to exceed Maximum Residue Limits(MRL). The highest detected samples were found in citrus fruits(83.9%). Among the detected compounds, carbendazim(13.1%), imazalil (11.7%), thiabendazole(10.7%) and fludioxonil(9.8%) were frequently found in fruits. A risk assessment of pesticide residues in fruits was performed by calculating Estimated Daily Intake(EDI) and Acceptable Daily Intake(ADI). Also, we were evaluated removal efficiency of pesticide residues by washing and peeling. The removal efficiency of pesticide residues in citrus and tropical fruits by peeling processes were 91.6%. After the washing process, the removal rates were 43.1%(Cherry, Grape, Blueberry). CONCLUSION: The level of pesticide residues in fruits was within the MRL. The range of %ADI values was from 0.00011 to 0.98795%. The process of washing or peeling reduces the level of pesticide residues. The results of this research concluded that the detected pesticides are not harmful to human being.