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As the increase of carbon dioxide in atmospheric accelerates climate change, various efforts have been performed to reduce carbon worldwide. Recently, as the concept of green carbon stored and sequestrated through photosynthesis by land plants has been emphasized to reduce carbon content from environments, the importance of carbon absorption survey for plant groups analysis of terrestrial ecosystems such as forests and river wetlands is increasing. Carbon absorption sources in terrestrial ecosystems exist in various forms of plant, soil, and topography, and represent various carbon absorption through physical, chemical and biological reactions between each other depending on the location and height of the plant groups. In this study, an industrial RTK drone capable of taking high-resolution images was used for efficient carbon absorption survey in Damyang stream wetland. Based on the global navigation satellite system by RTK, the location could be corrected in real time, and ecosystem surveys could be conducted on the height of the terrain with RTK drone. The point cloud technique of the high-density surface model was used to analyze the three-dimensional topography of areas that are difficult to access. Using the photo survey function of the RTK drone, it is expected to play an important role in understanding the total amount of green carbon of terrestrial ecosystems and carbon circulation of the land ecosystem by enabling the creation of topographic maps of stream wetlands, and riparian vegetation with complex terrain.

Objectives : This paper summarizes effective waste management and disposal methods for plastic and medical wastes during the prolonged COVID-19 pandemic.Methods : We reviewed the literatures reporting and identifying the current status and characteristics of wastes related to COVID-19, and the management and treatment guidelines for those wastes. We also investigated various technologies for waste treatment and disposal, and assessed the current status and future direction of the technologies in Korea.Results and Discussion : In the first half of 2020 in Korea, the amount of plastic waste produced had increased by 15.6% year-on-year, and medical waste production also increased significantly from 0.6 ton in January 2020 to 2,928 ton in August 2021. All of the infectious wastes are currently being incinerated in Korea, but there are concerns on air pollutant emissions and insufficient treatment facilities. Municipal solid waste also suffers from a lack of landfill capacity and low price competitiveness in the recycling industry.Conclusions : Policy and system need to be improved to reduce the infectious waste generation from the sources, and treatment and disposal technologies for produced wastes also need to be developed. Furthermore, hospitals and health care facilities should establish their own waste reducing systems which may include chemical treatment and sterilization units.

The abundant growth in cyanobacterial blooms poses severe ecological threats with a high risk to aquatic organisms and global public health. Control of cyanobacterial blooms involves spraying cyanobacteria removal materials, including coagulants. However, little is known about the fate of the coagulated-cyanobacteria-laden water. Here, we examined long-term changes in water quality following treatment with various coagulants and minerals for cyanobacterial removal when the coagulated cyanobacterial cells were not removed from the water. An experiment in a controlled water system tested the effects of six different compounds, one conventional coagulant, two natural inorganic coagulants, and three minerals. All tested coagulants and minerals exhibited >75% of cyanobacterial removal efficiency. However, compared to the control, higher concentrations of nitrogen were observed from some samples treated during the experimental period. After 20 months, the final total phosphorus concentration of the raw water increased 20-fold compared to the initial concentration to 11.82 mg/L, indicating significant nutrient release over time. Moreover, we observed that the decomposition of sedimented cyanobacterial cells caused the release of intracellular contents into the supernatant, increasing phosphorous concentration over time. Therefore, cyanobacterial cells should be removed from water after treatment to prevent eutrophication and maintain water quality.

Objectives:We analyzed the occurrence of blue-green algae at Algae Alert System and Water Quality Forecast System sites in Daegu and Gyeonsangbuk-do between 2012 and 2019.Methods:Data from 17 sites in Daegu and Gyeonsangbuk-do were collected and reclassified to 8 Nakdong river (ND) sites and 9 water source (WS) sites. Influencing factors on the occurrence of blue-green algae were investigated.Results and Discussion:At the ND sites, blue-green algae were observed in the range of 0-495,360 cells/mL. Between 2012 and 2019, the average number of blue-green algae increased as the sites go downstream from ND-1 (Sangju weir) to ND-8 (Dalseong weir), while the number of blue-green algae was lower at the site in-between weirs than the site adjacent to weir. At the WS sites, blue-green algae were observed in the range of 0-112,000 cells/mL. The average numbers of blue-green algae in 2014, 2015 and 2017 were higher than those of other years. The dominant species of blue-green algae was Microcystis at all the sites during the summer when the water temperature was high; when the water temperature was low Aphanizomenon had higher rates of dominance. Water temperature was positively correlated with the number of blue-green algae grown, while the dissolved oxygen concentration was found to have a negative correlation with it. pH and chlorophyll-a were less correlated.Conclusions:In Daegu and Gyeongsangbuk-do, the main stream of the Nakdong river showed higher blue-green algae occurrence than the water source sites. In most cases, Microcystis was dominant species. In the main stream of Nakdong river, blue-green algae tended to occur more downstream, and the number of blue-green algae was higher at sites close to weir than sites in-between weirs. The occurrence of blue-green algae was highly related to water temperature.

We developed a three-dimensional unstructured grid coastal and estuarine circulation model, named the General Ocean Model (GOM). Combining the finite volume and finite difference methods, GOM achieved both the exact conservation and computational efficiency. The propagation term was implemented by a semi-implicit numerical scheme, the so-called scheme, and the time-explicit Eulerian&ndash, Lagrangian method was used to discretize the nonlinear advection term to remove the major limitation of the time step, which appears when solving shallow water equations, by the Courant&ndash, Friedrichs&ndash, Lewy stability condition. Because the GOM uses orthogonal unstructured computational grids, allowing both triangular and quadrilateral grids, considerable flexibility to resolve complex coastal boundaries is allowed without any transformation of governing equations. The GOM was successfully verified with five analytical solutions, and it was also validated when applied to the Texas coast, showing an overall skill value of 0.951. The verification results showed that the algorithm used in GOM was correctly coded, and it is efficient and robust.

Replication of natural mixing through artificial water circulation techniques, such as convectional water circulation systems (CWCS), can break thermal stratification in stagnant water and suppress algal blooms. Here, the field performance of a novel CWCS was evaluated in a eutrophic reservoir (Shingal reservoir, South Korea) for three seasons between September 2016 and September 2018. The CWCS was deployed in a corner of stagnated water in the reservoir. The changes in water temperature and dissolved oxygen (DO) concentrations at different water depths were examined at the deployment site and two control sites within the stagnant area during the 2016 and 2017 seasons. In 2018, the performance of the CWCS in replicating natural mixing was assessed by monitoring water temperature changes at different depths at the CWCS unit deployment site and a comparison site with natural water flow. The differences in water temperature and DO concentrations between the epilimnion and the hypolimnion were significantly smaller at the deployment site than at the control sites, demonstrating the effectiveness of the CWCS in vertical and horizontal mixing as well as in oxygen transfer. The findings of the field study revealed that the CWCS effectively induced natural-like mixing without disturbing the hypolimnion.

The purpose of this study was to develop a two-dimensional shallow water flow model using the finite volume method on a combined unstructured triangular and quadrilateral grid system to simulate coastal, estuarine and river flows. The intercell numerical fluxes were calculated using the classical Osher-Solomon's approximate Riemann solver for the governing conservation laws to be able to handle wetting and drying processes and to capture a tidal bore like phenomenon. The developed model was validated with several benchmark test problems including the two-dimensional dam-break problem. The model results were well agreed with results of other models and experimental results in literature. The unstructured triangular and quadrilateral combined grid system was successfully implemented in the model, thus the developed model would be more flexible when applying in an estuarine system, which includes narrow channels. Then, the model was tested in Mobile Bay, Alabama, USA. The developed model reproduced water surface elevation well as having overall Predictive Skill of 0.98. We found that the primary inlet, Main Pass, only covered 35% of the fresh water exchange while it covered 89% of the total water exchange between the ocean and Mobile Bay. There were also discharge phase difference between MP and the secondary inlet, Pass aux Herons, and this phase difference in flows would act as a critical role in substances’ exchange between the eastern Mississippi Sound and the northern Gulf of Mexico through Main Pass and Pass aux Herons in Mobile Bay.

The algae bloom in river has been issued in Korea. In order to alleviate treatment load of water treatment plant and to meet water treatment capacity of the plant, a high-speed algae pretreatment methods connected with water intake pipe are required. In this study, a pilot-scale of pretreatment system was tested. It was consisted of coagulation and electro flotation processes. The algae pretreatment efficiency by the comparisons of chlorophyll-a, nutrients (total nitrogen, total phosphorous), and chemical oxygen demand (COD) concentration was evaluated. As a result, the system showed about 45% of removal efficiency by the only flotation separation without coagulation judged by chlorophyll-a concentration. On the other hand, the removal efficiency was improved with increase of coagulant dosage and electric power. It was improved to about 80% of chlorophyll-a concentration. The system could treat algae containing solution within a few minutes on the basis of residence time of flotation tank. Consequently, this study suggests that the system could be used as an algae pretreatment step in water treatment process.

This research was conducted to investigate the magnitude and nature of the emission of runoff pollutants with the goal of quantifying stormwater pollutant concentrations from driveways site. A statistical summary for concentration characteristics of driveway runoff is provided based on the various analysis techniques. Runoff water qualities in temporal variation were generally higher in wet season than in dry season with a high degree of variability. The 95 % confidence intervals of washed-off pollutant concentration are ranged to 82.4-141.4 mgL -1 for TSS, 53.3-87.6 mgL -1 for Turbidity, 19.0-38.7 mgL -1 for BOD, 34.0-59.2 mgL -1 for COD, 16.4-27.4 mgL -1 for DOC, 4.3-5.6 mgL -1 for TN and 0.25-0.34 mgL -1 for TP, showing the high values based on the surface or lake quality standards in Korea. The first flush effect is mostly occurred within initial 30 min of storm duration. Concentrations of water quality constituents in urban stormwater are often expressed in probabilistic terms using statistics such as the mean and standard deviation and selected quintiles. Three probability distributions, weibull in TSS and Turbidity, lognormal in BOD and COD and gamma in DOC, TN and TP were fitted and the goodness-of-fit was assessed using the Anderson-Darling test. The correlation matrix of all water quality variables shows significant relationships between all parameters (P

Contaminants such as organic matters, nutrients and toxic chemicals in rivers and lakes with a weak flow rate are first removed from the water and accumulated in the sediments. Subsequently, they are released into the water column again, posing direct/indirect adverse effects on the water quality and aquatic ecosystems. In particular, phosphorus is known to accelerate the eutrophication phenomenon when it is released into the water column via physical disturbance and biological/chemical actions as one of important materials that determine the primary production of aquatic ecosystems and an element that is stored mainly in the sediments in the process of material circulation in the body of water. In this study, the effect on reducing phosphorus release in sediments was analyzed by applying different capping materials to lake water, where the effect of aquatic microorganisms is taken into account, and to distilled water, where the effect of microorganisms is excluded. The experimental results showed that capping with chemical materials such as Fe-gypsum and SiO2-gypsum further reduced the phosphorus release by at least 40% compared to the control case. Composite materials like granule gypsum+Sand showed over 50% phosphorus release reduction effect. Therefore, it is determined that capping with chemical materials such as granule-gypsum and eco-friendly materials such as sand is effective in reducing phosphorus release. The changes in phosphorus properties in the sediments before and after capping treatment showed that gypsum input helped to change the phosphorus that is present in lake sediments into apatite-P, a stable form that makes phosphorus release difficult. Based on the above results, it is expected that the application of capping technology will contribute to improving the efficiency of reducing phosphorus release that occurs in river and lake sediments.

The structures of fresh water plume depending on estuarine geometries and wind directions (upwelling, onshore, downwelling, and offshore winds) were studied using the Regional Ocean Modeling System (ROMS). Four idealized estuaries, which are different in bathymetry, were considered. The results showed that the fresh water plume was restricted close to the shore line where a river was connected to the sloping shelf rather than the flat shelf due to the fast momentum exchanges from x, y to z momentums on the sloping shelf. Mild upwelling and offshore winds (  = 0.01Pa) enhanced stratification on the contrast to previous studies which showed that winds destroyed stratification by enhanced vertical mixing. However, downwelling and onshore winds had similar effects on the vertical structure of the fresh water plume as in previous studies enhancing vertical mixing. The plume was confined above the underneath submarine channel, thus the plume path was directly affected by the direction of the submarine channel on the shelf.

A three-dimensional ocean circulation model was applied to a shallow estuary, Mobile Bay, to study local wind setup and setdown. Tides started from the northern Gulf of Mexico propagates up to the Mobile River system which is located in the north of the Mobile Bay. However, the tides started in the south of Mobile Bay were distorted when travelling upstream while affected by river discharge and local winds. The water surface elevation was less/over predicted responding north/south winds, respectively, when winds only at the Dauphin Island station (DPI) were used. However, the model predicted water surface elevation better when using two local winds from DPI and Mobile Downtown Airport (MDA). Wind speeds were greatly reduced (~ 88%) in about 43 km distance between DPI and MDA, and the canopy effects may be the reason for this. For this reason, the local winds are greatly responsible for local surface elevation setup and setdown especially at the shallow estuary like Mobile Bay.

Cultivated lands within the river district are likely non-point sources of pollution that could be directly discharged into rivers and lakes, as well as identified as significantly risky areas for pollutant run-off during floods. In this study, major non-point sources in surface run-offs, from cultivated lands within the river districts, and their effects on the bodies of water in North Han River Basin were examined. It was found that pollutant concentrations in the run-offs from farms appeared to be generally higher than in the run-offs from paddies. Initial concentrations of pollutants during rainy seasons were usually higher than the medians of their concentration ranges, though not necessarily the highest. The unit loads of BOD from cultivated lands within river districts, which were proposed in this study for the first time in Korea, were 4.56, 3.35, and 10.26 kg/km2/year for paddies, farms, and greenhouses, respectively. Likewise the unit loads of total nitrogen (TN) were proposed as 1.54, 8...

The purpose of this study was to remove sediments obtained from breeding ground using supersonics and micro-air flotation method. Sediments from Tongyong breeding grounds showed no contaminations of heavy metals but had great amount of organics. Thus, efficient removal of sediments was required to preserve water quality near breeding ground. Supersonics treatment for sediments was determined to be essential because higher removal efficiency of sediments was obtained when supersonics treatment was used. In addition, application of coagulants increased removal efficiency because its usage increased particle size of sediments, which enabled easy trapping of sediments particle into micro-air bubbles. Removal efficiency of sediments slightly decreased from 95.8% (1 g/L) to 83.9% (8 g/L) at the tests for different amount of sediments, but most of tiny particles were removed from water where sand size particles were left in the bottom of reactors.

The high-speed algae pretreatment system consisted of coagulation and electro coagulation process was tested. This study examined algae removal efficiency by the comparison of chlorophyll-a concentration before and after treatment. As a result, the system showed about 45% of removal efficiency by the only flotation separation without coagulation. As increase of electric power and coagulant dosage, the removal efficiency was improved to about 80%. The system could treat algae containing solution with a few minutes on the basis of residence time of flotation tank. Consequently, this study suggests that the system could be used as a pretreatment step in water treatment process.

The field study was carried out to investigate runoff characteristics of non-point source (NPS) by cultivation activity in river district. Two sites were selected mainly as G region (paddy field, green house), located in Kwangju, Gyeonggi Province, and S region (ordinary field), located in Namyangju, Gyeonggi Province, those belong to Paldang reservoir watershed. The paddy field with water storage capacity showed a slow increase in runoff as rainfall intensity increases. Meanwhile, both green house and ordinary filed revealed a rapid increase. The average BOD runoff concentration of paddy field, green house, and ordinary field was 2.0 mg/L, 2.8 mg/L, 7.9 mg/L, respectively. It indicates that ordinary field shows the highest value in BOD, SS, T-N, and T-P concentration due to the soil loss during rainfall. As a result of runoff load estimation according to the field, a T-N runoff load of paddy field was 1,793.9 kg/year, higher than that of ordinary field. It was estimated that a SS runoff load of ordinary field was 69,704 kg/year and accounts for more than 70% of overall runoff load.

Waternode station is a floating composite water quality monitoring device. The waternode station houses the multiple water quality measurement devices, control panel for wireless communication and solar cells for applying electric power. The floating devices are classified into general model with vertical dropping system and river model without vertical dropping system. The water quality measurement device measures pH, water temperature, conductivity, dissolved oxygen, turbidity and nitrate. And it measures all parameters simultaneously. The control panel is used for IP-USN system. USN (Ubiquitous Sensor Network) is a network system by water quality measurement devices. IP-USN is a USN system that identifies particular sensor connected to the internet. The data information is transferred by wireless modem based on TFB (Triple Frequency Band). Field application results showed that the waternode station is a reliable and cost-effective water quality monitoring solutions.

Metal elements or other constituents transported in urban and transportation land use rainfall runoff are often adsorbed on or incorporated with entrained particles that are ubiquitous in such runoff. EPP(Expanded Polypropylene) engineered media with a large surface area was developed to treat road runoff. Field application of particle filtration reactor(PFR), which combined the EPP engineered media with filtration called EcoTank system, provided control of water quality. Under the operating conditions with 0.55 hours hydraulic retention time(HRT) and a capable of treating a maximum road runoff 9.5 m3/h, the mean residual Cd, Cr, Cu, Pb and Zn were 0.24, 2.8, 13.4, 11 and 112.3 ㎍/L and corresponding percentage mean removal values were 91, 93, 85, 91 and 80%, respectively. Results suggest that a properly designed PFR can provide effective in situ control for particles and could be combined with or function separately from source control.

The water quality measurement device that we developed measures pH, water temperature, conductivity, dissolved oxygen, turbidity and nitrate. And it measures all parameters simultaneously. The water resistant and screw packing technology also applied for improved mechanical reliability during water quality monitoring. A comparison between the performances of major company products (YSI, Hydrolab etc.) and this device don't provide a stark contrast. This device was verified through the KOREA’s Environmental Examination Methods. This device is offered reliable and cost-effective water quality monitoring solutions. Upgrades will be available and will include the technologies that are self-cleaning optical sensors with integrated wipers remove biofouling and maintain high data accuracy and optimal power management and built-in battery compartment extends in situ monitoring periods.

Due to its irregular structure, the efficiency of the pelletized fibrous filter can be improved if the target substance is line-shaped. Thus, this study was conducted to examine the applications of the pelletized fibrous filter for biological sewage water with line-shaped particles. Towards this end, the pelletized fibrous filter was applied to advanced treatments in which the particles in the sewage water in the supernatant using solid-liquid separation from the final-settling reservoir was filtered with pelletized fibrous filters. To determine the process efficiency of the filter device, a multiparameter water quality analyzer and a data transmission system were established, which showed the efficient process even at a large distance, as well as the good operational status of the filter device. The pilot plant operation results showed that the concentration of TSS in the influent at 20-75 mg/L was reduced to 0.4-10 mg/L in the processed water. The average processing efficiency was 94.9% between 71.4 and 97.9%, and particularly, that of the suspended solids was very high. The results also showed that 27.2% CODMn, 22.5% T-N, and 30.0% T-P were removed.

EPP(Expanded Polypropylene) media with a large surface area was developed to treat the first flush of storm water from motorway. A series of studies have been carried out concerning the main mechanism of physical characteristics with the filtration and adsorption of EPP media in EcoTank system in order to evaluate the performance risk for treating trace metals (Cd, Cr, Cu, Pb and Zn) under uncertainty. In view of quantitative and qualitative risk analysis, this study assesses the uncertainty analysis involved in predicting of treating heavy metals from road runoff using an EcoTank system. Results of treatment performance estimation after the treatment of trace metals using an uncertainty analysis were 50.0.% probability (class 3; moderate) for Cd, 52.0% probability (class 4; high) of Cr, 47.1% probability (class 3; moderate) for Cu, 44.4% probability (class 3; moderate) for Pb and 51.2% probability (class 4; high) for Zn, respectively. The performance risk values of all the heavy metals satisfied the acceptable criteria.

With the acceleration of urbanization, impervious surface spreads due to increase of rainfall effluent; consequently, plenty of pollutants occur instantaneously, and severity of a problem caused by being worse of the river and water system is coming to the forefront. Nation Water Quality Inventory reported that 30% of the cause of water quality getting worse is caused by non-point pollutants, and 64% of the cause of polluted water quality of the lake around North Carolina is resulted from non-point pollutants of urban area. This study developed a system that treats and removes pollutants occurring in an impervious area of the urban district by using polymer media. Polymer media, made from polypropylene materials, has float ability and an irregular form. Also this study showed that polymer media has an excellent filtering function of pollutants due to porosity on the surface, and the increase of specific surface area, so that it has an excellent function to remove suspended solids (SS), organic materials and nutritive salts in effluent water on the road side. Treatment efficiency of pollutants in an impervious area of the urban district through application of polymer media to the site is 92.1% and average EMC of suspended solids (SS) is 19.74 mg/L. In addition, treatment efficiency of CODcr is 82.3%, and the efficiency of TN and TP is 50.4% and 73.9%, respectively.

The cost for nonpoint source in urban area tends to increase as it's distanced farther from the pollution source. Thus it's more effective to dispose of the pollution at the pollution source. It becomes more difficult when nonpoint source is flowed into the surface water by stormwater. In case of combined sewer, increasing stormwater on impermeable surface causes the Combined Sewer Overflows (CSOs) containing the high level of pollutants which runs into the water system through the storm overflow diverging tank without treatment process. A huge amount of CSOs is generated instantly and as it carries the pollutants on impermeable surface as well as the deposits in sewage pipe, it's necessary to develop the technology for treatment of CSOs. This study was intended to develop the solid fabric filter which will be suitable for treatment of CSOs and the characteristic and performance of solid fabric filter were evaluated.

In this study, to effectively control urban non point source pollution, natural and artificial materials which were processed in various ways were charged as a filter media in a real size urban non point source pollution plant(EcoTank) and compared and evaluated the efficiency of filtering solid and organic compounds. The efficiency of filter media was evaluated after collecting dust from urban surface and artificially producing runoffs to evaluate runoff control efficiency of pollutants that caused from pollution in urban streets. To evaluate the efficiency of pollutants runoff control depending on different filter types, EPP(Expanded polypropylene), GAC(Granular activated carbon), Zeolite, Mix-1(EPP in the upper part, GAC in the lower part), Mix-2(GAC in the upper part, EPP in the lower part) was charged to the EcoTank and conducted experiments in an identical condition[6]. As a result of the filter evaluation using real size reactor, EPP was identified as the best filter media for non point source pollution runoff control, and the efficiency was in the following order: EPP > Mix-1 > Mix-2 > GAC > Zeolite.

This research was conducted to investigate the application of the novel upflow-type filtration device using hydrophobia media made of expanded polypropylene (EPP) from driveways site. The higher level of motorway-derived heavy metal contamination exists in stormwater runoff from a road section and the heavy metal levels were higher than the regulated Korean environmental guideline in lake and river. For Cd, Cr, Cu, Pb and Zn, the influent event mean concentrations (EMCs) during 8 storm periods were 2.75, 37.3, 90.5, 118.5 and 546.5 µg/L, respectively. The novel upflow-type filtration device with main mechanism of filtration and adsorption showed removal (>91%, >93%, >85%, >91% and >80%) of the studied heavy metals (Cd, Cr, Cu, Pb and Zn) and differences of medians of removal efficiencies among heavy metals were not statistically signficant by Kruskal-Wallis test (p>0.05) during 8 storm events. It is found that EPP media is very effective at the removal of the heavy metals, and the magnitude of heavy metal removal in a decreasing order is Cr, Cd, Pb, Cu and Zn.

Since the non point source is unspecified and estimating the degree of occurrence or identifying causing factors are difficult, it is not easy to control. Road runoff is considered a major source of pollution in developed urban sites. Road surfaces accumulate significant quantities of pollutants including nutrients, heavy metals and polycyclic aromatic hydrocarbons(PAHs). Many studies have characterized the constituents of stormwater. These constituents include polycyclic aromatic hydrocarbons(PAHs). Urban non-point source pollutant reducing treatment System is a part of the road runoff treatment which expanded polypropylene(EPP) media with a large surface area to treating the first flush of stormwater from road in field. Urban non-point source pollutant reducing treatment System consist of a container, a total 8.89m2 volume(3.6m(L), 1.3m(W), 1.9m(H)) which is made up of two element; sedimentation chamber of storage tank and filter tank. Under the operating conditions with 0.55h hydraulic retention time(HRT) and a capable of treating a maximum road runoff of 9.5m3/hr, the mean residual total PAHs were 0.699~1.339 µg /L and the percentage mean removal values were 61.4~69.7%, respectively.

Pollutants such as heavy metals and PAHs (Polynuclear Aromatic Hydrocarbons) in stormwater runoff are a major problem in urban areas because these pollutants are discharged directly, in most cases without any treatment, into the receiving environments like river and lake. Since many of the pollutants are associated with suspended particulate materials in stormwater, SS (suspended solids) is of acknowledged importance in stormwater runoff treatment by BMPs (best management practices). Filtration, which is commonly used for removing particulate matter in stormwater structural BMPs, depends on various factors (e.g., filter media size, flow rate, bed depth, filter surface properties, etc). Especially, the characteristics of filter media are important factor affecting removal efficiency of pollutants and replacement period of filter media in filtration performance. In this study, EPM (expanded polypropylene media) as a filter media was manufactured at different expansion ratios (i.e., 5, 10, 15 times) and tested in the up-flow filtration for removing pollutants in urban stormwater runoff. The specific surface area of EPM10, EPM15, EPM30, EPM54 was 0.760 m2/g, 0.799 m2/g, 0.812 m2/g, 0.845 m2/g, respectively. The SS removal efficiency (64.1%) by EPM media was higher than that (44.2%) by sand media. In case of EPM10 media, it took 175min of removal rate of filtration system to be approached under 50% and EPM15 media was spent 110min. However, the SS removal efficiency of EPM15 was over 10% higher than that of EPM10. The CODCr removal efficiency of EPM media was also increased with increasing expansion rate. The experimental results in this work show that pollutant removal efficiency by EPM media was increased with increasing expansion ratio but replacement period of media was decreased. EPM media are expected to adsorb non-biological organics like PAHs owing to its hydrophobicity.

In this study, the capping effects of granular gypsum (Ca2SO4·2H2O) and sand on sediment and water column were evaluated in in-situ experiments in Lake Paldang. The results indicate that capping treatment is very effective for the restoration of eutrophied lake. It was demonstrated that phosphorus, T-N and T-P concentration in the water column of treated basin was relatively lower than control basin. As a consequence of reduction of nutrient concentration by capping treatment, chlorophyll-a concentration in treated basin was considerably lower than control basin. The chlorophyll-a concentration in water column could be reduced to 52% and 25% as compared to control basin, respectively, by the capping treatment with gypsum and sand. From the experimental results, it was concluded that gypsum was more effective capping material than sand for controlling of nutrients and chlorophyll-a. In addition, capping with gypsum bring calcium cation into sediment, which offer more site for phosphorus to bind. In case of the capping with gypsum, apatite P composition, mainly consist of Ca boun P, in the sediment increased from 24% to 43% for the two month of operation.

With the development of economic status and living standard, eutrophication of lakes has become serious problem. Due to continuous inflow of external nutrients into lakes, phosphorus, a critical nutrient for lake production, has been accumulated in large amount in the sediment. Thus phosphorus rich sediment acts as an internal nutrient source and reduction of phosphorus release from the sediment is very important for restoring eutrophied lakes. Among the various strategies to restore lakes, in-situ capping is known as an attractive and cost-effective method for remediation of contaminated sediments. In this paper, lab-scale batch column test was conducted to evaluate the characteristics of capping materials on reduction of phosphorus release from the sediment. Three different types of capping materials including sand, zeolite, and natural gypsum (CaSO4·2H2O) were used. Each column was filled 7 cm with sediment and covered by 1 cm of sand, zeolite, and natural gypsum, respectively. The change of water quality in supernatant solution was monitored for 10 days in each column. From the results, addition of gypsum showed higher treatment efficiency than sand and zeolite. In case of the capping with gypsum, it was found that the phosphorous release from the sediment could be reduced by around 90% as compared with untreated column. On the contrary, phosphorus reduction efficiencies of sand and zeolite were 60% and 14%, respectively. Moreover, in case of the capping with sand and zeolite, sudden increase of phosphorus concentration was observed with the generation of CH4 gas from sediment. Methanobacterial ebullition is one of the important factors for transporting phosphorus from sediment into water column. It was reported that the addition of gypsum could reduce the progress of methanogensis by supplying sulfate into sediment, which enhances the activity of sulfate-reducing bacteria (SRB) and mineralization rate of organic matter.

Lab-scale batch experiments using several 150-L transparent acrylic reactors were conducted to develop optimum capping materials that can capture phosphorous released from polluted lake sediments. The sediment used in the experiment was very fine clay (7.7 Φ in mean grain size), and organic carbon (Corg) content was as high as 2%. Four kinds of batches with different capping materials; powdered-gypsum (CaSO4·2H2O), granular-gypsum, sand, composite material (gypsum+sand), and one control batch were operated for 45 days. Phosphorous fluxes released from bottom sediments in the control batch were estimated to be 4.3 mg·m-2·d-1, while 0.9 mg·m-2·d-1, 1.0 mg·m-2·d-1, 2.2 mg·m-2·d-1, and 0.5 mg·m-2·d-1 in the batch capped with powdered-gypsum, granular-gypsum, sand, and composite material, respectively. The results obtained from lab-scale batch experiments show that there were 80% reduction of phosphorous for some materials such as powdered-gypsum, granular-gypsum, and composite material, whereas sand only about 50%. Increase in apatite-P fraction (48% → 80%) in the gypsum batches, compared to the control batch, indicates that abundant Ca2+ and SO4 2- ions from the gypsum added into oxygen-depleted sediment surface might have supplied abundant oxygen by reducing the sulfate ions very actively, resulting in Ca-P precipitates.

In this study, the generation characteristics of the Combined Sewer Overflows (CSOs) that occur in urban areas were investigated. In addition, performance evaluation of the CSO treatment efficiency was conducted through the field application of a high-speed filtering apparatus using a fibrous filter medium for the treatment of the CSOs that occurred in an urban area. The study site, a city located in Seoul, South Korea, was one that included the typical residential and commercial districts. The daily average flow rate of the Eungbong drainage area, which was the study site, was 92.5 m 3 /hr during the dry season, and the daily average flow rate ranged from 70.2 to 129.2 m 3 /hr, indicating a wide daily-average-flow-rate range. The highest flow rate was shown at around 9 a.m. on weekdays and at around 11 a.m. on weekends. The average influent concentrations that occurred during the dry season were 19.0 mg/L (BOD), 15.9 mg/L (COD), 10.9 mg/L (SS), 33.9 mg/L (TN), and 0.5mg/L (TP), and the hourly concentration ranges turned out to be 4.1~43.5 mg/L (BOD), 9.5~26.8 mg/L (COD), 3.6~33.0 mg/L (SS), 25.5~52.2 mg/L (TN), and 0.4~0.9 mg/L (TP). The results of the field application of a high-speed filtering apparatus using a fibrous filter medium showed that the average treatment efficiency of SS was 63.7% during the dry season. The average treatment efficiency of SS during rainfall was 84.2% (1 st ), 88.0% (2 nd ), 87.5% (3 rd ), 85.8% (4 th ), 75.8% (5 th ), 75.5% (6 th ), and 90.3% (7 th ), and exhibiting more than 80% treatment efficiency. In the case of organic contaminants like BOD, however, low treatment efficiency (less than 30%) appeared. Judging from the above results, it is difficult to expect a treatment effect if the influent concentration is less than 30 mg/L in the case of an organic material when the high-speed filtering apparatus is applied to the site, and even in the case of an influent concentration of more than 30 mg/L, the treatment efficiency is about 30% on average. The treatment effect of the particulate material (SS) remained quite high, however, without significant restrictions on the filtering liner velocity and influent concentration. The results of the analysis of the characteristics of the CSOs in urban areas and of the application of a highspeed filtering apparatus using a fibrous filter medium are expected to be utilized as basic data for management alternatives to reduce rainfall runoff loads with respect to overflows that occur during rainfall.

While more attention has been paid in recent years to urban point source pollution control, no considerable measures have been taken to control urban non-point source pollution. Contaminants from non-point sources deposited on urban impermeable surfaces such as road and highway are easily released to the public waters by rainfall, leading to the deterioration in water quality in urban area. Experiments were performed using a reactor and real rainwater runoff obtained from road surfaces at various pollutant loading and rainfall intensity to determine the criteria for the first flush rainwater and to evaluate the applicability of the reactor for treating road runoff. The results at different rainfall intensities show that the medium PPB is superior to the other media for water permeability. PPB was not blocked at 10 mm/hr rainfall, and its permeability was stable. On the other hand, PVS and PPF resulted in a substantial overflow ratio even at 1 mm/hr rainfall intensity. Comparison of treatment efficiencies for suspended solids showed that all media showed similar removal efficiency ranging from 91% to 95%. However, PPB seems to be better than the other media considering its higher water permeability. PPB and PPF, both hydrophobic, yielded over 76% of heavy metal removal. But the hydrophilic media PVS showed much smaller removal efficiency ranging from 26% to 47%. The treatment efficiencies over PAHs (Poly Aromatic Hydrocarbons) showed the similar removal efficiency ranging from 66% to 97% for all three media. In this study a reactor using filter media was investigated to reduce the level of contamination in urban road runoff.

Urban runoff is one of the major sources that contaminates water supplies because it contains toxic compounds such as heavy metals and PAHs (poly aromatic hydrocarbons) as well as suspended solids, organic compounds, and nutrients. The eingineered polymetric media in this research were developed as filtering media in the storm water treatment equipment. The media used in this study can remove contaminants in urban runoff via adsorption and filtration. The engineered media composed of polypropylene and anion surfactant were foamed to have buoyacy and then shattered by mechanical device for efficient filtration. Surface characteristics of the engineered media were determined by using a scanning electron microscope and a microscope. Results indicated that surface area of the engineered media were increased from less than 0.05m2/g for the neither foamed nor shattered media to 7.82m2/g for the foamed and shattered media. Specific gravity of the media that were foamed and shattered was 0.108~0.154 whereas the non-treated media had specific gravity of 0.914. Fractal dimension of media was measured for the irregularity of the media shape and the media that had high fractal dimension value was performed high filtration efficiency of suspended solids in runoff.

In this study, the potential for the application of the bioaugmentation to Cd and Zn contaminated sediment was investigated. A batch experiment was performed in the lake sediments augmented with Ralstonia sp. HM-1. The degradation capacity of 18.7 mg-DOC/l/day in the treatment group was bigger than that of the blank group (4.4 mg-DOC/l/day). It can be regarded as the result of the reduction of the metal concentration in the liquid phase due to adsorption into the sediments, with the increased alkalinity resulting from the reduction of sulfate by sulfate reducing bacteria (SRB). The removal efficiency of cadmium and zinc in the treatment group was both 99.7% after 35 days. Restrain of elution to water phase from sediment in the Ralstonia sp. HM-1 added treatment group was also shown. In particular, the observed reduction of the exchangeable fraction and an increase in the bound to organics or sulfide fraction in the treatment group indicate its role in the prevention of metal elution from the sediment. Therefore, for bioremediation and restrain of elution from the sediment polluted by metal, Ralstonia sp. augmentation with indigenous microorganism including SRB, sediment stabilization and restrain of elution to surface water is recommended.