• Journal of Wetlands Research
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• v.20 no.3
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• pp.263-271
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• 2018

In this study, we analyzed the removal efficiency of ammonia nitrogen and phosphate dependant on the column depths using various absorbents such as zeolite silica sand, and activated carbon through the column test. In addition, we analyzed electrochemical adsorption behaviors of ammonia nitrogen and phosphate through the quantum mechanical calculation based on density functional theory calculation. Experimental results represent the removal efficiency of ammonia nitrogen and phosphate are zeolite > activated carbon > silica sand, and activated carbon > zeolite > silica sand, respectively. Zeolite shows high adsorption property for ammonia nitrogen over 90%, regardless of the column depth, while activated carbon exhibits high adsorption property for both ammonia nitrogen and phosphate as the column depth for filter media increases. Theoretical findings using DFT calculation for the adsorption behaviors of adsorbents (activated carbon and silica sand) and nutrients ($PO_4{^{3-}}$, $NH_4{^{+}}$) show that activated carbon represented narrower HOMO-LUMO band gap with high adsorption energy, and even more favorable environment for electron adsorption than silica sand, which leads to the effective removal of nutrients.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.266-272
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• 2003

This study was conducted to evaluate effects of 2 constructed wetlands with different vegetation states (plumpton park wetland and Woodcroft park wetland) for reducing non-point source pollution from small watershed consisted of residential and agricultural area in suburban district of Sydney, Australia. The total nitrogen and phosphate removal efficiency of Plumpton park constructed wetland, composed of stable and dense vegetation, were 38.3% and 26.2% and Woodcroft park constructed wetland having still poor vegetation due to the short time to settle down transplanted plants after construction, showed relatively low removal efficiency of 20.2% and 14.0%. The removal efficiency of inorganic nutrients such as $NH_4-N$, $NO_3-N$, $PO_4^{-3}$ were higher than total nitrogen and phosphate because plants and microorganisms in rhizosphere of constructed wetlands took up inorganic nutrients shortly. According to the type of wetland inflow, the nutrients removal efficiency of storm water flow was lower than base flow.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.101-107
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• 2010

In order to deal with the problem that phytoremediation takes long time in achieving the practical effect, the enhanced phytoremediation by Barnyard grass (Echinochloa crus-galli) was conducted. In addition, we examined the synergistic effect by adding PSM (phosphate -solubilizing microbes) and EDTA (ethylenediaminetetraacetic acid) to the arsenic contaminated soil in the vicinity of the abandoned mine. The removal efficiency of arsenic in the site with PSM application increased about 16% when compared to control site, which was due to increase of plant biomass. The EDTA has been successfully utilized in respect of enhanced mobility and solubility of arsenic in the soil. As a result, BF (bioaccumulation factor) significantly increased but the inhibition of plant growth resulted in 20% reduction of arsenic removal efficiency. The application of PSM and EDTA may enhance the efficiency of phytoremediation. However, the time and method of EDTA application should be further examined to reach the maximum removal efficiency.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.745-753
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• 2007

By struvite and hydroxyapatite crystallization, was high concentration of nitrogen and phosphorus in wastewater simultaneously. Particularly, removal of nitrogen and phosphate for crystallization have been applied to landfill leachates and animal wastewater. The purpose of this study is to decide the optimum struvite crystallization factors, sequence of $Mg^{2+}$ addition, pH control and the molar ratio of $Mg^{2+}$ over $PO_4^{3-}$. In conclusion, dosage of the magnesium followed by pH control formed magnesium hydroxide, so pH was decreased. Therefore, pH adjustment should followed by after magnesium dosage and then pH should be adjusted to 11. Over pH 10, it was not good for struvite crystallization efficiency by side reaction. Following of the $Mg^{2+}$ and the $PO_4^{3-}$ are dosed excessively, the removal efficiency of the $NH_4^+$ increased. A molar ratio of $Mg^{2+}:NH_4^+:PO_4^{3-}$, 1.3:1:1.3 was the most on effective for $NH_4^+$ removal at pH 9.5. But for the perfect removal $NH_4^+$, it is thought to be that molar ratio should be 2:1:2.

• Environmental Engineering Research
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• v.10 no.5
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• pp.205-212
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• 2005

The study was conducted to investigate the removal of heavy metals by using Hydroxyapatite(HAp) made from waste oyster shells and wastewater with high concentration of phosphorus. The maximum calcium concentration for the production of HAp in this study was released up to 361 mg/L at pH of 3 by elution experiments. When the pH was at adjusted 6, the maximum calcium released concentration was 41 mg/L. During the elution experiment, most of the calcium was released within 60 minutes. This reaction occurred at both pH levels of 3 and 6. The result of the XRD analysis for the HAp product used in this study shows the main constituent was HAp, as well as OCP. The pH was 8.6. As the temperature increased, the main constituent did not vary, however its structure was crystallized. When the pH was maintained at 3, the removal efficiency decreased as the heavy metal concentration increased. The order of removal efficiency was as follows: $Fe^{2+}$(92%), $Pb^{2+}$(92%) > $Cu^{2+}$(20%) > $Cd^{2+}$(0%). Most of these products were dissolved and did not produce sludge in the course of heavy metals removal. As the heavy metal concentration increased at pH of 6, the removal efficiency increased. The removal efficiencies in all heavy metals were over 80%. From the analysis of the sludge after reaction with heavy metals, the HAp was detected and the OCP peak was not observed. Moreover, lead ion was observed at the peaks of lead-Apatite and lead oxidant. In the case of cadmium, copper and iron ions, hydroxide forms of each ion were also detected.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.47-55
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• 2007

The waste water treatment facility at rural and mountainous region in catchment areas of dams should be small scale. The wastewater treatment facility of small scale has some specification as follows;1)simple process, 2)low maintenance cost, and 3)high removal efficiency. So, we developed the bioreactor which can be satisfied with the specification of small scale waste water treatment facility. The bioreactor consisted of the anoxic and oxic zone. The two zones were effectively separated by cone type baffle. By the effective separation through CTB, the nitrification and denitrification reaction occurred effectively. Therefore, the removal efficiency of total nitorgen (TN) increased compared to other types of baffle. And, we put into the bio activated media in oxic zone to increase the concentration and activity of microbiology. The media contained the components which were made of many kinds of the minerals to increase the activity of microbiology. Additionally, we observed that the phosphate removal efficiency increased by bio activated media. This is resulted from the coagulation-sedimentation reaction by mineral in components. The average removal efficiencies of TN and TP during Run 2 were 69 and 89% which were 4 and 25% higher than those during Run 1 without the MA, respectively. For BOD, COD, SS and TKN, the average removal efficiencies at Run 2 were slightly higher than those at Run 1. Therefore, we could maintain the high concentration and high activity of microbiology through bioreactor developed in this study. And the removal efficiency of TN and TP increased.

• Journal of Korean Society on Water Environment
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• v.29 no.2
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• pp.170-175
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• 2013

Achieving very low phosphorus levels in treated wastewater will require the installation of additional treatment. Phosphorus removal experiments by chemical coagulation were carried out for the effluent of wastewater treatment plant in this study. TP (total phosphorus) or phosphate were highly related to the addition of PAC (poly aluminium chloride) which is one of the inorganic coagulants. But, organic polymer did not significantly affect the phosphorus removal efficiency. Polymer affected the flocculation of particle especially particle matter less than 10 micrometer so, the number of micro particles was decreased by polymer dose. Chlorination would not affect on chemical coagulation process and TP and turbidity could be effectively removed by the co-addition of PAC and polymer.

• Journal of Environmental Science International
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• v.12 no.7
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• pp.791-799
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• 2003

This study was carried out to get more operational characteristics of the sequencing batch biofilm reactors with media volume/reactor volume ratio of 15 %, 25 % and 35 %. Experiments were conducted to find the effects of the media packing ratio on organic matters and nutrients removal. Three laboratory scale reactors were fed with synthetic wastewater. During studies, the operation mode was fixed. The organic removal efficiency didn't show large difference among three reactor of different packing media ratios. However, from the study results, the optimum packing media ratios for biological nutrient removal was shown as 25%. The denitrifying PAOs could take up and store phosphate using nitrate as electron acceptor.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.231-237
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• 2016

The purpose of this study is to analyze phosphate adsorption characteristic of the filter media applied in water purification technology. And it is also to observe the removal efficiency of the technology that was developed by combining the purification abilities of filter media and the vegetation mat. The filter media, Adphos, is the subject of this study. The result of adsorption test shows that $PO_4{^{3-}-P}$ adsorption characteristics of Adphos is determined by the Langmuir isotherm model fitting and the $q_m$ (maximum adsorption amount) value is calculated as 1.162 mg/g. To verify the removal efficiency of the purification technology, a lab-scale reactor, including a 400 mm depth of filter bed filled by Adphos, was manufactured. Yellow flag Iris (Iris pseudacours L.) was planted on the vegetation bed and the coir-roll was used to fix the root of vegetation. The reactor ran 8 hours per day over 71 days, and the results of filtration experiment show that average removal efficiency of SS, T-N and T-P were calculated as 94%, 41% and 64% respectively. With these results, it was proved that the purification technology is highly effective. And for the long-time use, a maintenance guide is also required.

• Journal of the Korean Applied Science and Technology
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• v.32 no.1
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• pp.78-84
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• 2015

The purpose of this study is to evaluate the removal efficiency of phosphorus from synthetic waste water by reduction and oxidation reaction of Cu-Zn metal alloy. Cu-Zn metal alloy applied in this study is composed of 40% of Zn and 60% of Cu, which is so called Muntz metal. And the fibrous type of metal alloy has approximately $200{\mu}m$ of thickness. Metal is oxidized in an aqueous solution to generate electron and metal ion. The mechanism of phosphate treatment is co-precipitation of metal ion and phosphorous ion at various pH and temperature. The treatment efficiency showed the maximum at a one cycle treatment. This result means that the surface area of reaction material is sufficient enough to get reaction equilibrium. Experiment is conducted at various pH from 5 to 9, and showed the maximum efficiency at pH 8. Phosphorous is dominated as a type of $H_2PO_4{^-}$ and $HPO_4{^{2-}}$ at this pH condition. We could not consider the temperature effect independently, because phosphorous removal efficiency showed such a complex mechanism. We could get high efficiency at lower temperature in this research.