• Journal of Wetlands Research
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• v.7 no.4
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• pp.43-50
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• 2005

Wetlands can transform or remove pollutants from water body, such as nitrogen, phosphate, and organics. Many researches were conducted in relation to uptake process by aquatic plants in wetlands. However, water purification processes in wetlands are the results of physical, chemical and biological, especially microbiological reactions. As such, understanding on microbial processes is of great importance. In this study, we used pondor marsh-type wetland microcosms for investigating the water purification capacity and microbial functions, namely, extracellular enzyme activities, nitrification and denitrification. In a pond system, removal efficiencies of $NO_3{^-}$ and $PO{_4}^{3-}$ were 96% and 100 % respectively, while those in a marsh system were 94%, 100% respectively. These high removal efficiencies appeared to be caused by high adsorption ability to soils and microbial functions in wetland.

• Journal of Environmental Impact Assessment
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• v.32 no.5
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• pp.291-304
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• 2023

Harmful algal blooms (HABs) have become an increasing concern in terms of human health risks as well as aesthetic impairment due to their toxicity. The reduction of water pollutants, especially nutrients from non-point sources in a reservoir watershed, is fundamental for HABs prevention. We investigated the pollutant removal efficiencies of a constructed wetland to evaluate its feasibility as a method for controlling non-point sources located in the Annaecheon stream within the Daecheong Reservoir watershed. The overall removal efficiencies of pollutants were as follows: BOD 14.3%, COD 17.9%, SS 50.0%, T-N 19.0%, and T-P 35.4%. These results indicate that constructed wetlands are effective in controlling pollutants from non-point sources. The seasonal variation in removal efficiency depended on the specific pollutants. The removal efficiencies of BOD, COD, and T-N were stable throughout the year, except during winter, which might have been influenced by lower microorganism activity. In contrast, T-P showed a consistent removal efficiency even during the winter season, suggesting that the wetland can reduce external phosphorus loading to the reservoir. Regarding the effects of pollutant loadings on removal efficiency, the effluent concentrations of all pollutants were significantly decreased compared to those in the influent in case of middle and high loadings. This demonstrates that constructed wetlands can handle high pollutant loads, including the initial runoff during rainfall, to prevent reservoir eutrophication. Despite the various strengths of wetland water purification, there are limitations as passive treatment. Therefore, more case studies should be conducted to suggest optimum operational conditions for constructed wetlands, taking into consideration reservoir-specific characteristics.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.489-497
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• 2006

The feasibility of the Natural and Ecological Wastewater treatment System (NEWS) was examined for rural wastewater treatment in Korea. The intermittent trickling biofilter with high hydrophilic filter media was used for pretreatment for suspended solids and organic pollutants. The subsequent constructed wetland with porous granule materials was used for promoting nutrient removal. The results show that the removal efficiencies of the system were high with respect to the water quality parameters except COD. Even if the effluent from the biofilter did not meet the guidelines for wastewater treatment plant effluent in Korea in terms of $BOD_5$ and TN, the final effluent of the system meets the guidelines us to good performance of the constructed wetland. The regression analysis between pollutant loading rate and removal rate indicated that the system could have stable removal for SS, $BOD_5$, TN, and TP in the given influent ranges. The analysis in the winter period indicated that the wetland covered with transparent polycarbonate glass had the statble performance during the winter period dus to increase of temperature inside the wetland without any heating system. With the stable performance, effective poilutant removal, low maintenance, and cost-effectiveness, the NEWS could be considered as an alternative treatment system for decentralized regions and rural communities in Korea.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.9-16
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• 2009

Further treatment facility using various filter materials was evaluated to treat effluent of constructed wetland. Further treatment facility was installed with 1m length in outlet of 3 constructed wetland (unplanted constructed; reed bed constructed wetland; cattail bed constructed wetland) using 3 filter materials (slag, activated carbon, oyster shell). Flow rate of three further treatment facility was 63 $m^3$/day (slag), 19 $m^3$/day (activated carbon), and 81 $m^3$/day (Oyster shell). COD removal rate of slag, activated carbon, and oyster shell was 6 %, 24 %, 1 %, and removal mass was 32 g/day, 30 g/day, and 5 g/day, respectively. All of further treatment facility was effective to removal organic materials. T-N and T-P removal rate of activated carbon was 24 % and 4 %, and slag and oyster shell was not effective to remove T-N and T-P. Overall, further treatment facility was effective to remove organic mater, constructed wetland combined with further treatment facility can remove nutrient and organic matters effectively.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2005.04a
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• pp.264-269
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• 2005

• The Korean Journal of Food And Nutrition
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• v.10 no.3
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• pp.382-386
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• 1997

In the present study, an attempt was made to investigate the effects of steeping treatment on browning of onion hydrolysate. After steeping treatment with solvents, phenols content of methanol and ethanol were showed 25.1mg/ml and 24.9mg/ml. And absorbance of methanol and ethanol was showed 0.26 and 0.22. L and b value of treatment with methanol and ethanol were lower than other solvents. Browning reaction of onion hydrolysate was decreased with increasing concentration of ethanol. Treatment of above 80% ethanol was effective to remove phenols and was showed a low color intensity. Treatment with 80% ethanol was more effective than addition of cystein to remove phenols and to decrease browing degree.

• Journal of Wetlands Research
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• v.6 no.2
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• pp.57-63
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• 2004

More than 1000 natural and constructed wetlands have been used to improve water quality. The general results showed that the highest removal efficiency was 84% for BOD and the lowest one was 48% for total nitrogen concentration. In addition, total phosphous removal efficiency was 67%, and the removal efficiencies are related to inflow loading. Researches donducted in Korea have focused on input-output mass balance and uptake by aquatic plant. As such little information if available about complex processes regulating water quality and role of microbes. Therefore, to determine the optimal design for construct, and methods to operate constructed wetland, researches about complex mechanisms of contaminant removal and interdisciplinary researches are necessary.

• Journal of Digital Convergence
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• v.11 no.5
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• pp.237-243
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• 2013

This study aims to examine the modified $A^2/O$ process is useful to reduce the environmental pollution caused by nutrient in wastewater. Specific results are as follows: The removal rate was evaluated at each time period, ie., 18h, 8h, 6h, and 3h after the reaction started. The anoxic rate was more than 94-97% from 18h to 6h but was less than 50% before 6h. Thus, the test of nitrification was done using 6h as the optimal anoxic retention time and the aerobic retention time set at 24h. When the flow change was 1:1, the average ammonia concentration inputted was $30mg/{\ell}$. Returned top nitric acid solution and the concentration of ammonia solution falling into the anoxic reactor was about 50％ of the initial concentration, and the flow change was 1:2, the concentration of ammonia falling into the anoxic reactor was about 62% of that of influxed ammonia. And the results of this study showed that the nitrogen removal rate can be improved by inputting untreated nitric acid and changing the flow of top nitrate solution using the modified $A^2/O$ method.

• Resources Recycling
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• v.12 no.4
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• pp.38-43
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• 2003

Phosphate is an essential material for the growth of organisms. However. since relatively small amount is required. a large amount of phosphate is abandoned in wastes and wastewater. which contaminate the ecological environment including aquatic system. Purpose of this study is to treat especially high concentrated phosphate wastewater by use of calcium precipitation method. The pH range considered was from 6 to 12 and the maximum removal of phosphate was attained at pH 12. The con-centration of phosphate was observed to decrease rapidly until a half amount of calcium ion to its equivalent for the formation of calcium phosphate precipitate was added. which resulted in the decrease of the remaining concentration of phosphate down to 0.0027 mM. The effect of fluoride ion was examined and the concentration ratio between the phosphate and fluoride ion did not have any significant influence on the removal efficiency of phosphate. The effect of pH was also investigated. With the increasing of the pH in solution, the removal rate of phosphate was increased. Also it was investigated that the effect of fluoride on the phosphate removal was not significant.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.5
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• pp.314-324
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• 2011

Algal biomass cultivated by wastewater is potentially useful resource for biodiesel production. However, little is known about algal nutrient metabolism and microbial interaction with bacteria under real municipal wastewater condition. In this work, we characterized nitrogen and phosphorus removals of municipal wastewater by a representative wastewater-growing algal population. Ankistrodesmus gracilis SAG 278-2, and analyzed its ecological interaction with wastewater bacterial communities. Compared to wastewater sludge itself, algal-bacterial co-culture improved nutrient removal. According to bacterial community analysis with 16S rRNA genes, a selective and dominant growth of a Unclassified Alcaligenaceae population resulted from algal growth in the algal-bacterial co-culture. The selectively stimulated bacterial population is phylogenetically close to Alcaligenes faecalis subsp. 5659-H, which is known to be co-present interact with algae in aquatic environment. These findings suggest that algal growth/metabolism may have effects on selection of a specific bacterial population in algal-bacterial co-cultures that can efficiently remove nutrients from municipal wastewater.