• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.4 no.4
• /
• pp.56-63
• /
• 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 of Water and Wastewater
• /
• v.29 no.3
• /
• pp.359-370
• /
• 2015

This study developed an up-flow wetland providing either an eco-friendly follow-up process of medium-sized public treatment facility for livestock manure or a non-point source pollution controller near livestock farms. The four bench-scale up-flow wetlands were operated with four different bed media sets. The removal efficiencies of the wetland effluent for CODCr, TN, TP, SS were 35.2 %, 29.5 %, 31.2 % and 52.2 % for set 1(Blank, without reed, with bio-ceramic), 40.6 %, 43.4 %, 42.2 % and 55.4 % for set 2(with bio-reed & without bio-ceramic), 45.2 %, 48.7 %, 46.6 % and 66.3 % for set 3(with bio-reed & bio-ceramic), 32.9 %, 27.3 %, 29.3 % and 54.1 % for Set 4(with reed & bio ceramic), respectively. The set 3 condition having a mixture of bio-reed and bio-ceramic showed the highest efficiency in the bench-scale evaluation. This study suggests a mixture of bio-reed and bio-ceramic as suitable bed media in the construction of artificial wetlands near livestock farms. Soils including the bed media were monitored during the evaluation for trace elements. Soil analysis results were satisfied with the Korean Soil Contamination Standard. This study showed that the up-flow constructed wetland was feasible to treat the effluent livestock wastewater treatment facility.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.231-231
• /
• 2020

Unlike conventional treatment technologies, the performance of nature-based facilities were susceptible to seasonal changes and climatological variabilities. This study evaluated the effects of seasonal variables on the treatment performance of constructed wetlands (CWs). Two CWs treating runoff and discharge from agricultural and livestock areas were monitored to determine the efficiency of the systems in reducing particulates, organics, and nutrients in the influent. For all four seasons, the mean effluent suspended solids concentration in the agricultural CW (ACW) increased by -2% to -39%. The occurrence of algal blooms in the system during summer and fall seasons resulted to the greatest increase in the amount of suspended materials in the overlying water. unlike ACW, the livestock CW (LCW) performed efficiently throughout the year, with mean suspended solids removal amounting to 61% to 68%. Algal blooms were still present in LCW seasonally; however, the constant inflow in the system limited the proliferation of phytoplankton through continuous flushing. The total nitrogen (TN) and total phosphorus (TP) removal efficiencies in ACW were higher during the summer (21% to 25%) and fall (8% to 21%) seasons since phytoplankton utilize nitrogen and phosphorus during the early stages of phytoplankton blooms. In the case of LCW, the most efficient reduction in TN (24%) and TP (54%) concentrations were also noted in summer, which can be attributed to the favorable environmental conditions for microbial activities. The mean removal of organics in ACW was lowest during summer season (-52% to 35%), wherein the onset of algal decay triggered a relative increase in organic matter and stimulate bacterial growth. The removal of organics in LCW was highest (54 % to 55%) during the fall and winter seasons since low water temperatures may limit the persistence of various algal species. Variations in environmental conditions due to seasonal changes can greatly affect the performance of CW systems. This study effectively established the contributory factors affecting the feasibility of utilizing CW systems for treating agricultural and livestock discharges and runoff.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.10
• /
• pp.893-900
• /
• 2009

To estimate the contribution of epiphytic algae attached on reed to organic matter production in constructed wetland, primary productivity by epiphytic algae was investigated in two sub-wetlands (Banweol and Donhwa wetlands) of the Sihwa Constructed Wetland (CW) with different chemistry of inflows. Chlorophyll a concentration of epiphytic algae was higher in the Banweol wetland (range:37~3,581 mgChl.a/$m^2$surface stem, average:655 mgChl.a/$m^2$surface stem) than the Donhwa wetland (range:87~2,093 mgChl.a/$m^2$surface stem, average:527 mgChl.a/$m^2$surface stem). In contrast, assimilation number (AN) representing photosynthetic activity was higher in the Donhwa wetland with low TN/TP ratio than the Banweol wetland. A negative correlation (r=0.46) was observed between TN/TP ratios of inflows and AN in two wetlands, implying that high photosynthetic activity of epiphytic algae may be related with low TN/TP ratio. The areal primary productivity ranged from 307 to 2,473 mgC/$m^2$/day in the Banweol wetland and from 756 to 2,096 mgC/$m^2$/day in the Donghwa wetland, showing high productivity in summer. Average primary production was lower in the Banweol wetland (1,166 mgC/$m^2$/day) than the Donghwa wetland (1,467 mgC/$m^2$/day), although the standing crop (as chlorophyll a concentration) was high in the Banweol wetland. This result may be due to the low photosynthetic activity of epiphytic algae in the Banweol wetland with high TN/TP ratio. The annual primary production (300 tonC/year) of epiphytic algae contributed 33% of the total production in the Sihwa CW. An excessive organic matter production in constructed wetland can negatively affect the efficiency of water treatment. Therefore, the role of epiphytic algae should be considered in management of constructed wetland for water treatment.

• Korean Journal of Environment and Ecology
• /
• v.34 no.6
• /
• pp.515-529
• /
• 2020

Constructed wetlands undergo biological and physical changes such as an increase in the proportion of arid plants due to the natural succession process after formation. It can adversely affect not only the purification function but also the habitat of species. As such, this study aims to identify environmental factors affecting biodiversity and propose management plans based on the monitoring results of physical environmental changes and the emergence of species in seven constructed wetlands selected based on the water depth and surrounding conditions among the lands purchased by the Nakdong River basin. We examined the environmental conditions and emergence of the Odonata, which is a wetland-dependent species, to predict the trend of changes in biodiversity and abundance. The results showed that the open water area decreased as the emergent plants spread to the deep water in 2015 compared to 2012 when they were initially restored to a depth of 0.2 to 1 m. While a total of 54 dragonfly species were observed, the habitat diversity, such as vegetation, water surface, and grassland, remained similar to the initial formation of the wetlands despite the expansion of the emergent plants. On the other hand, the number of Agrionidae species, which prefer areas with fewer aquatic plants, decreased between 2012 and 2015 due to the diminished water surface. The p-values of the differences in the number of species and population between wetlands by year were 2.568e-09 and 1.162e-08, respectively, indicating the statistically significant differences. The decrease in open water surface was found to have the greatest effect on the biodiversity and habitat density of dragonflies. The time-series survey of constructed wetlands confirmed that the spread of Phragmites communis, P. japonica, Typha orientalis, etc., caused a decrease in species diversity. It suggests that environmental management to maintain the open water surface area is necessary.

• Journal of Wetlands Research
• /
• v.6 no.4
• /
• pp.59-69
• /
• 2004

Constructed wetlands are regarded as an important water treatment system for agricultural water quality improvement and management. The purpose of this study is to evaluate the application of subsurface flow wetland(SFW), using the Pharagmites australis as macrophytes, and to clarify the basic and essential factors to be considered in the construction and management of constructed wetlands. This study was carried out relatively short hydraulic residence time(HRT), 6hr ~ 72hr (3days), using eutrophic reservoir water with relatively low concentrations of influent and large quantity to be treated. The effluent satisfied the criteria of agricultural water quality. Removal efficiencies of Biochemical oxygen demand(BOD), Chemical oxygen demand(COD), Suspended solids(SS) and Chlorophyll a(Chl-a) were high in HRT 24hr, not any more significant increasement of removal efficiencies in HRT 48hr and 72hr. However, removal efficiencies of nitrogen and phosphorus increased as HRT increased, showing the highest efficiency at the 72hr of HRT in nitrogen, and 48hr in phosphorous. The SFW was very effective system for reservoir water quality improvement, and had the advantages of the reduction of purchasing cost to land required, lack of odors, and harmful insects, especially mosquito, the improvement of the scenic beauty and minimal risk of public exposure. Therefore, it was evaluated that the SFW was very available water treatment system for the water quality improvement of agricultural reservoir. However, it was need to consider with application of the SFW in high cost of construction and troublesome of management.

• Korean Journal of Environmental Agriculture
• /
• v.29 no.2
• /
• pp.146-151
• /
• 2010

In order to improve T-N and T-P removal in HF (horizontal flow)-HF hybrid constructed wetlands by natural purification method for treating the hydroponic wastewater in greenhouses, the efficiency of water treatment as affected by the injection method of hydroponic wastewater, the addition of special filter media, the particle size of filter media, and the injection ratio of hydroponic wastewater in $1^{st}$ HF and $2^{nd}$ HF beds were investigated in small-scale HF-HF hydroponic wastewater treatment apparatus. Removal rate of T-P in the water in HF-HF hydroponic wastewater treatment apparatus with calcite as affected by addition method of special filter media was higher than that in HF-HF hydroponic wastewater treatment apparatus with other filter media. Removal rate of BOD, COD, SS, T-N and T-P in the water in mixed filter media with calcite were 86, 84, 87, 50 and 97%, respectively. Removals of pollutants except for T-P in the water were slightly different. Therefore, it should be considered that the removal rate of T-P was good for calcite in HF-HF hydroponic wastewater treatment apparatus. To improve T-N and T-P removal, the optimum particle size of filter media was 1.2 mm, and the optimum injection ratio ($1^{st}$ HF bed : $2^{nd}$ HF bed) of hydroponic wastewater was 60:40.

• Ecology and Resilient Infrastructure
• /
• v.4 no.3
• /
• pp.142-148
• /
• 2017

Nitrogen and phosphorus are key factors in causing eutrophication of water body. In this study, ceramics media was selected to increase the removal efficiency of nitrogen and phosphorus. We designed vertical, horizontal flow constructed wetlands to create aerobic and anaerobic flow conditions by using the media, then proceeded to performance evaluations after acrylic reactors were produced. In the case of vertical and horizontal flow constructed wetlands, we measured oxygen concentrations to evaluate aerobic and anaerobic conditions. we got the result of 2.7 mg/L in the aerobic condition, N.D in the anaerobic condition respectively, which suited our purpose. The result of the combined vertical and horizontal flow condition showed that the removal efficiency of SS was 94%, 91%, 61% at 140 min, 80 min, 60 min of running times, respectively, and the removal efficiency of T-P was 84%, 71%, 63% during each running time. In case of T-N, the removal efficiency was 63%, 49%, 42% during each running time. We found that the reactor exerted better removal efficiency when in the short time compared to 12 - 24 hr residence time of existing wetlands. In this study, we conducted experiments to explore functional effects after applying combined vertical and horizontal flow methods in the field. Further study will be carried out to identify its mechanism and administrative perspective.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.12
• /
• pp.1287-1292
• /
• 2006

Constructed wetlands are well known as highly efficient system to treat wastewater from different sources. Among the constructed wetlands, upflow types of constructed wetlands have become a common selection of wastewater during the last decade. We conducted a pilot scale study at peen house on treating potential of nutrients by upflow vegetated filter(UVF) pilot wetland which was combined with hydrodynamic separator and used the cattail plant(Typha angustifolia), and operated with artificial nutrients influent. This study evaluate the performances of upflow vegetated fille, in removal of nutrients. The objectives of this study were two-fold: (i) to evaluate the nutrients removal performance of pilot-scale upflow vegetated filter, filled with a mixture of perlite and soil media and planted with cattails and (ii) to design of scale-up upflow vegetated filter using Froude number. Results indicated that, under the condition of the ranges of hydraulic surface load rate were $22.7{\pm}9.6\;m^3/m^2/day$, the average removal of $COD_{Mn}$, and TN, TP were 57.5%, 40.0% and 41.5%, respectively. Computational fluid dynamics, FLUENT 6.0 program was used to predict the distribution of velocity in UVF and hydrodynamic separator. Full scale UVF was designed using the Froude number scale-up method that was assumed geomertic similarity between model and prototype. Result shows that the UVF with 3 m diameter has capacity of design sewage flowrate 75 $m^3/day$.

• Journal of Wetlands Research
• /
• v.22 no.2
• /
• pp.161-170
• /
• 2020

Constructed wetlands (CWs) are widely used to solve water quality problems caused by diffuse pollution from agricultural areas; however, phytoplankton blooms in CW systems can occur due to long hydraulic retention time (HRT), high nutrient loading, and exposure to sunlight. This study was conducted to evaluate the efficiency of a CW designed to treat agricultural diffuse pollution and develop a design concept to improve the nature-based capabilities of the system. Monitoring was conducted to assess contribution of individual wetland components (i.e. water, sediments, and plants) in the treatment performance of the system. During dry days, the turbidity and particulates concentration in the CW increased by 80 to 197% and 10 to 87%, respectively, due to the excessive growth of phytoplankton. On storm events, the concentration of particulates, organics, and nutrients were reduced by 43% to 70%, 22% to 49%, and 15% to 69% due to adequate water circulation and constant flushing of pollutants in the system. Based on the results, adequate water circulation is necessary to improve the performance of the CW. Free water surface CWs are usually designed to have a constant water level; however, the climate in South Korea is characterized by distinct dry and rainy seasons, which may not be suitable for this conventional design. This study presented a concept of multifunctional design in order to solve current CW design problems and improve the flood control, water quality management, and environmental functions of the facility.