• Journal of Wetlands Research
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• v.17 no.4
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• pp.325-331
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• 2015

Due to urbanization and increase in impervious area, changes in natural water circulation system have become a cause of groundwater recharge reduction, streamflow depletion and other hydrological problems. Therefore, this study developed the infiltration planter techniques applied in an LID facility treating roof stormwater runoff such as, performance of small decentralized retention and infiltration through the reproduction of natural water circulation system and use of landscape for cleaning water. Assessment of an infiltration planter was performed through rainfall monitoring to analyze the water balance and pollutant removal efficiency. Hydrologic assessment of an infiltration planter, showed a delay in time of effluent for roof runoff for about 3 hours and on average, 79% of facilities had a runoff reduction through retention and infiltration. Based on the analysis, pollutant removal efficiency generated in the catchment area showed an average of 97% for the particulate matter, 94% for the organic matter and 86-96% and 92-93% for the nutrients and heavy metals were treated, respectively. Comparative results with other LID facilities were made. For this study, facilities compared the SA/CA to high pollutant removal efficiency for the determination to of the effectiveness of the facility when applied in an urban area.

• Clean Technology
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• v.12 no.2
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• pp.67-77
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• 2006

A simple dual sludge process, called as $KNR^{(R)}$ (Kwon's Nutrient Removal) system, was developed for small sewage treatment. It is a hybrid system that consists of an UMBR (Upflow multi-layer bioreactor) as anaerobic and anoxic reactor with suspended denitrifier and a post aerobic biofilm reactor, filled with pellet-like media, with attached nitrifier. To evaluate the stability and performance of this system for small sewage treatment, the pilot-scale $KNR^{(R)}$ plant with a treatment capacity of $50m^3/d$ was practically applied to the actual sewage treatment plant, which was under retrofit construction during pilot plant operation, with a capacity of $50m^3/d$ in a small rural community. The HRTs of a UMBR and a post aerobic biofilm reactor were about 4.7 h and 7.2 h, respectively. The temperature in the reactor varied from $18.1^{\circ}C$ to $28.1^{\circ}C$. The pilot plant showed stable performance even though the pilot plant had been the severe fluctuation of influent flow rate and BOD/N ratio. During a whole period of this study, average concentrations of $COD_{cr}$, $COD_{Mn}$, $BOD_5$, TN, and TP in the final effluent obtained from this system were 11.0 mg/L, 8.8 mg/L, 4.2 mg/L, 3.5 mg/L, 9.8 mg/L, and 0.87/0.17 mg/L (with/without poly aluminium chloride(PAC)), which corresponded to a removal efficiency of 95.3%, 87.6%, 96.3%, 96.5%, 68.2%, and 55.4/90.3%, respectively. Excess sludge production rates were $0.026kg-DS/m^3$-sewage and 0.220 kg-DS/kg-BOD lower 1.9 to 3.8 times than those in activated sludge based system such as $A_2O$ and Bardenpho.

• Journal of Wetlands Research
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• v.25 no.2
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• pp.145-158
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• 2023

Constructed wetlands (CWs) are effective technologies for urban wastewater management, utilizing natural physico-chemical and biological processes to remove pollutants. This study employed a bibliometric analysis approach to investigate the progress and future research trends in the field of CWs. A comprehensive review of 100 most-recently published and open-access articles was performed to analyze the performance of CWs in treating wastewater. Spain, China, Italy, and the United States were among the most productive countries in terms of the number of published papers. The most frequently used keywords in publications include water quality (n=19), phytoremediation (n=13), stormwater (n=11), and phosphorus (n=11), suggesting that the efficiency of CWs in improving water quality and removal of nutrients were widely investigated. Among the different types of CWs reviewed, hybrid CWs exhibited the highest removal efficiencies for BOD (88.67%) and TSS (95.67%), whereas VSSF, and HSSF systems also showed high TSS removal efficiencies (83.25%, and 78.83% respectively). VSSF wetland displayed the highest COD removal efficiency (71.82%). Generally, physical processes (e.g., sedimentation, filtration, adsorption) and biological mechanisms (i.e., biodegradation) contributed to the high removal efficiency of TSS, BOD, and COD in CW systems. The hybrid CW system demonstrated highest TN removal efficiency (60.78%) by integrating multiple treatment processes, including aerobic and anaerobic conditions, various vegetation types, and different media configurations, which enhanced microbial activity and allowed for comprehensive nitrogen compound removal. The FWS system showed the highest TP removal efficiency (54.50%) due to combined process of settling sediment-bound phosphorus and plant uptake. Phragmites, Cyperus, Iris, and Typha were commonly used in CWs due to their superior phytoremediation capabilities. The study emphasized the potential of CWs as sustainable alternatives for wastewater management, particularly in urban areas.

• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.157-162
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• 2004

Constructed wetlands are considered as an important tool for wastewater treatment, wastewater management and flooding control. In addition, one of the most promising technologies for application in many countries seems to be constructed wetlands, due to their properties such as utilization of natural processes, simple construction, operation and maintenance, process stability, cost effectiveness, etc. This study considered possibility of treatment of livestock wastewater using a constructed wetland. The removal efficiencies of $COD_{cr}$, TOC, TN, TP, SS, and color were 97.6%, 96.6%, 97.0%, 96.7%, 99.0%, and 85.6%, respectively. In particular, SS was completely removed. However, $Cl^{-}$ concentration of the constructed wetland effluent was higher than that in influent. In conclusion, constructed wetlands could be applied to livestock wastewater treatment if $Cl^{-}$ would be properly treated. Further, it needs time for stabilization to reduce the pollutants which were accumulated in soil.

• Environmental Engineering Research
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• v.20 no.3
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• pp.277-284
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• 2015

Experiments for highly concentrated contaminants in pig waste slurry were carried out for the feasibility test of a pilot-scale innovative process scheme of engaging autothermal thermophilic aerobic digestion (ATAD) and expended granular sludge bed (EGSB) followed by sequencing batch reactor (SBR) system. Contaminants in pig waste slurry such as organic substance, total nitrogen (TN), ammonia nitrogen and total phosphorus (TP) contents were successfully reduced in the system. Total volatile solids (TVS) and chemical oxygen demands (COD) for organic matter in the feed were 32.92 g/L and 42.55 g/L respectively, and they were reduced by about 98.7% and 99.2%, respectively in the system. The overall removal efficiencies for TN and ammonium nitrogen were found to be 98.1 and 98.5%, respectively. The overall removal efficiency for total phosphorus was also found to be 92.5%. Faecal coliform density was reduced to <$1.2{\times}10^4CFU/g$ total solids. Biogas and $CH_4$ were produced in the range of 0.39-0.85 and $0.25-0.62m^3/kg$ [VS removed], respectively. The biogas produced in the system comprised of $295{\pm}26ppm$ (v/v) [$H_2S$].

• Environmental Engineering Research
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• v.20 no.1
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• pp.99-104
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• 2015

The purpose of this study is to evaluate the performance of forward osmosis (FO) system for harvesting microalgae cultivated in secondary sewage effluent. Microalgae species used in this study were chlorella sp. ADE4. The drawing agents used for forward osmosis system were seawater and concentrate of sea water reverse osmosis (SWRO) system. Chlorella sp. ADE4 cultured in secondary sewage effluent illustrated moderate efficiency in removal of total nitrogen (TN) (68%) and superior performance in total phosphorus (TP) removal (99%). Comparison of seawater and SWRO concentrate as drawing agent were made in FO membrane separation of the microalgae. The result from this study depicts that SWRO concentrate is strong drawing agent in FO membrane system providing an average dewatering rate of $4.8L/(m^2{\cdot}hr)$ compared to seawater with average dewatering of $2.9L/(m^2{\cdot}hr)$. Results obtained from this study indicated that FO system could be viable option for harvesting the microalgae for further biodiesel production. SWRO concentrate as a drawing agent could be very important finding in field of membrane technology for disposal of SWRO concentrate.

• Journal of Korean Society on Water Environment
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• v.30 no.5
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• pp.532-538
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• 2014

A cylinder-shaped filter was developed to manage the runoff from construction sites. Compressed air was used for back-washing and pore sizes of filter were $23{\mu}m$ and $46{\mu}m$. The turbid water was prepared using sediments in construction sites. The grain size analysis showed that grains smaller than $38{\mu}m$ and larger than $335{\mu}m$ in size constituted 34.4 % and 37.6 %, respectively. Removal efficiency of the filter on turbidity, SS, COD, TN and TP showed 25~37%, 20~40%, 50~55%, 23~27% and 14~20%, respectively, whereas their removal efficiecy by using coagulant PAC showed 77~84%, 70~83%, 53~60%, 27~36%, and 59~75%, respectively. The filtration time was determined to be around 10 to 20 minutes. Back-washing for 10 seconds by pressurized air resulted in a satisfactory regeneration efficiency. According to the aforementioned test results, the cylinder-shaped filter is effective in reducing turbidity and would be suitable for practical application in construction sites and farms.

• Environmental Engineering Research
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• v.21 no.1
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• pp.36-44
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• 2016

Constructed wetlands are established efficient technologies and provide sustainable solution for wastewater treatment. Similarly, biochar, which is an organic material, produced by means of pyrolysis, offers simple and low cost techniques to treat water and reduce carbon footprint. Combining both of these technologies can greatly augment the efficiency of the system. The objective of this study was to evaluate the efficiency of constructed wetlands by using biochar as media. Horizontal wetland beds with dimension ($1m{\times}0.33m{\times}0.3m$) were prepared using gravels and biochar, and cultivated with the Canna species. Synthetic wastewater was passed through these beds with average flow rate of $1.2{\times}10^{-7}m^3/sec$ achieving a retention time of three days. Pollutant removal performance was compared between the controlled and experimental wetland beds. This study reveals that the wetland with biochar were more efficient as compared to the wetland with gravels alone with average removal rate of 91.3% COD, 58.3% TN, 58.3% $NH_3$, 92% $NO_3-N$, 79.5% TP, and 67.7% $PO_4$.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.1
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• pp.23-32
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• 2010

The capacity of natural purification was limited by the interruption of natural flow and the problems such as eutrophication were occurred by nutritive salts accumulation in stagnant stream. Moreover, the inflow of non-point sources causes non-degradable materials to increase in stagnant stream. In this study, an upflow biological activated carbon (BAC) biofilm process comprised of anoxic, aerobic 1, and aerobic 2 reactors were introduced for treatment of stagnant stream and SS, $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, TN, and TP were monitored in the upflow BAC biofilm reactors with continuous cycling. In order to simulate stagnant stream, the lake water of amusement park and golf course were stored as influent in a tank of $2m^3$ and hydraulic retention time (HRT) was changed into 6, 4, and 2 hours. At HRT 4hr and the lake water of amusement park as influent, the removal efficiencies of SS, $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, TN, and TP showed the best water quality improvement and were 69.8, 83.0, 91.3, 74.1, 74.7, and 88.9%, respectively. At HRT 4hr and the lake water of golf course as influent, the removal efficiencies of SS, $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, TN and TP were 78.5, 78.0, 80.2, 74.9, 55.6 and 97.5%, respectively. As the results of polymerase chain reaction - denaturing gel gradient electrophoresis (PCR-DGGE), microbial community was different depending on influent type. Fluorescence in situ hybridization (FISH) showed that nitrifying bacteria was dominant at HRT 4 hr. The biomass amount and microbial activities by INT-DHA test were not decrease even at lower HRT condition. In this study, the upflow BAC biofilm process would be considered to the water quality improvement of stagnant stream.

• Korean Journal of Environment and Ecology
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• v.23 no.6
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• pp.569-576
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• 2009

Sediment and nutrient loading caused by the removal of forest cover and alteration of agricultural lands in catchments have led to the deterioration in Lake Shirarutoro. To examine the effects of deforestation and agricultural activities on water quality, I examined changes in total nitrogen (TN) and total phosphorus (TP) of lake water induced by land use change, and compared them with the various research data produced over the years. Our investigation showed that the level of TN and TP in the lake water decreased when forest cover increased but increased when farmland area increased. The concentration of TN and TP was high in Lake Shirarutoro despite that its catchment was surrounded by large forests and small farmlands. This result indicates that land uses near Lake Shirarutoro have affected the quality of the lake water. I have examined the changes of sediment yield in the lake's catchment over the last approximately 300 years. Eleven core samples were obtained from the lake sediment and analyzed to establish a chronology after using two tephra layers (Ko-c2 in 1694 and Ta-a in 1739) and a $^{137}Cs$ peak (in 1963). The average sediment yield under the natural condition during the first two periods was 8.4 tons/$km^2$/year in 1694~1739 and 8.9 tons/$km^2$/year in 1739~1963 respectively. The conversion of the Shirarutoro catchment into agricultural lands and deforestation intensified, leading to an increased sediment yield of 21.1 tons/$km^2$/year during 1963~2007.