• Korean Journal of Microbiology
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• v.51 no.4
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• pp.374-381
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• 2015

Occurrences of coastal dredged materials are ever increasing due to port construction, navigational course maintenance and dredging of polluted coastal sediments. Ocean dumping of the coastal dredged materials has become virtually prohibited as London Treaty will be enacted as of the year 2012. It will be necessary to treat and recycle the dredged materials that may carry organic pollutants and heavy metals in a reasonable and effective process: collection of the dredged materials, liquid and solid separation, and treatment of organic compounds and heavy metals. In this study we have developed a continuous bioreactor system that can treat a mixture of silt and particulate organic matter using a microbial consortium (BM-S-1). The steady-state operation conditions were: pH (7.4-7.5), temperature ($16^{\circ}C$), DO (7.5-7.9), and salt concentration (3.4-3.7%). The treatment efficiencies of SCOD, T-N and T-P of the mixture were 95-96%, 92-99%, and 79-97%. The system was also effective in removal of heavy metals such as Zn, Ni, and Cr. Levels of MLSS during three months operation period were 11,000-19,000 mg/L. Interestingly, there was little sludge generated during this period of operation. The augmented microbial consortium seemed to be quite active in the removal of the organic component (30%) present in the dredged material in association with indigenous bacteria. The dominant phyla in the treatment processes were Proteobacteria and Bacteroidetes while dominant genii were Marinobacterium, Flaviramulus, Formosa, Alteromonadaceae_uc, Flavobacteriaceae_uc. These results will contribute to a development of a successful bioremediation technology for various coastal and river sediments with a high content of organic matter, inorganic nutrients and heavy metals, leading to a successful reuse of the polluted dredged sediments.

• 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.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.85-92
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• 2006

To evaluate the primary production and nutrient uptake of macrophytes in Lake Paldang, this study investigate the vegetation areas of six dominant aquatic plants including Typha angustifolia, Zizania latifolia, Phragmites australis, Trapa japonica, Nelumbo nucifera and Savinia natans, and contents of carbon, nitrogen and phosphorus of each macrophyte. Total vegetation area of six dominant aquatic plants was 1.37 $km^2$. Among them, Typha angustifolia was the most wide-distributed species which occupied the 46.7% of total vegetation area. Littoral zone of South Han river had the largest vegetation area with 0.458 $km^2$, and North Han river, Kyungan river and confluence area in the order named. The results of the contents of carbon, nitrogen and phosphorus of macrophytes showed that the carbon contents of emergent macrophytes was higher than that of other life-forms. The nitrogen content of Salvinia natans, free-floating macrophyte was highest and that of Typha angustifolia, emergent macrophyte was lowest. The phosphorus content of Trapa japonica showed the highest content of phosphorus among six macrophytes and emergent macrophytes such as Zizania latifolia and Phragmites australis showed lower contents of phosphorus than other life-forms. The annual net primary production of macrophytes in Lake Paldang, 2004, was calculated as 758.4 ton C $yr^{-1}$ and the annual net nitrogen and phosphorus uptake of macrophyte was 16,921 kg $yr^{-1}$ and 1,841.0 kg P $yr^{-1}$ respectively. Comparing the total budget of organic carbon, nitrogen and phosphorus in Lake Paldang, the amount of primary production and nutrient uptake by macrophytes take a small portion in total budget implying macrophytes do not play an important role in budget of matters in river-type lake, Lake Paldang.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7227-7236
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• 2015

The survey revealed that, due to the discharge characteristics of seafood wastewater, irregular inflow loads were caused, making it difficult to treat the wastewater safely. It is crucial for the operation of pressure and floating tanks for the treatment of high-concentration organic wastewater such as seafood wastewater. The survey of operation factors for the pressure and floating tanks revealed this: A/S ratio 0.05 (design criteria 0.01), the pressurized air pressure 8bar(design criteria 6bar), the pressure tank pressure 6bar (design criteria 4.5bar), and HRT 60sec(design criteria: 10sec). Also, the recirculation rate was changed to over 40%(design criteria: 30%), and the surface load rate was changed to under $13.7m^3/m^2{\cdot}hr$(design criteria: under $17.7m^3/m^2{\cdot}hr$); thus, compared to the initial design criteria, the operation factors were changed according to inflow characteristics, thus enhancing the pressure and floating tank performance. The survey of inflow load revealed BOD 140.7%, $COD_{Mn}$ 120.32%, and SS 106.3%, compared to the inflow design criteria, as well as T-N 135.5% and T-P173.3%, higher than the design criteria. The survey of the treatment facility annual operation cost revealed high portions in sludge treatment cost(27.7%) and chemicals costs(26.0%), and the sludge treatment cost will likely further increase due to the ban on ocean dumping. The unit cost for the treatment of seafood wastewater was found to be KRW 3,858 per ton, more than 27 times higher than the sewage treatment cost(KRW 142.6/ton), presumably because the seafood wastewater contains high-concentration organic substances and nutritive salts.

• Korean Journal of Ecology and Environment
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• v.36 no.4 s.105
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• pp.447-454
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• 2003

Aluminum coagulant was applied to two eutrophic lakes (Lake Sukchon, in Seoul, and a pond on the campus of Kangwon National University), to precipitate suspended particles and phosphate from the water column. Aluminum sulfate (alum) was used for seven treatments and polyaluminum chloride (PAC) was used for one treatment. The effect of treatment varied depending on the dose of alumium coagulant. Particles and phosphate were completely precipitated from the water column with a dose of 10.0 mgAl/l. Partial removal was observed at doses of 3.3 and 1.8 mgAl/l, but not at 0.45 mgAl/l. Therefore, coagulant should be applied at a dose over the threshold in order to remove particles effectively, which seems to be between 1.8 and 10.0 mgAl/l. The length of treatment effect was determined by new inputs of nutrients and particles from external sources. Renewal of pond water by stream water caused recovery of algal growth in Lake Sukchon, and rainfall runoff and ground water pumping caused a return of turbid water in the campus pond. During treatment there was no sign of decreasing pH, or harmful effects on fish or mussels. Aluminum coagulant may be an economically feasible alternative for water quality improvement when the external control of pollutant sources is difficult. However, repeated application is required when there is a renewal of lake water or new input of nutrients.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.353-359
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• 2013

The objectives of this study were to investigate effectiveness of the Compressed Air Jet (CAJ) System for cleaning up shorelines contaminated with crude oils and to examine effects of the system on total petroleum hydrocarbon (TPH) removal and microbial community changes before and after remediation of the oil-contaminated shorelines. These data will lead to better understanding of optimized remediation process. About 66% of TPH reduction was observed when the contaminated site was treated with the CAJ System 2, 3, 4, and 5 times. This treatment system was more efficient than the seawater pumping system under similar treatment conditions (by 40%). By the way, little oil degrader communities were observed despite a potential function of the air jet system to stimulate aerobic oil degraders. The apparent low population density of the oil degraders might be as a result of low concentration of TPH as a carbon source and limiting nutrients such as nitrogen and phosphorus. It was proposed that the CAJ System would contribute significantly to removal of residual oils on the shorelines in combination with addition of these limiting nutrients.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.481-487
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• 2016

In this research, a pilot scale hybrid rain garden system was developed in order to investigate the efficiency in the different components of the hybrid rain garden system and at the same time evaluate the initial efficiency of the system in treating urban stormwater runoff prior to its actual use in the field. Experimental runs were conducted using synthetic runoff having target concentrations similar to that of the typical runoff characteristics found in different countries and in Korea. With the employment of the hybrid rain garden system, hydrologic improvement was observed as the system demonstrates an approximately 95% reduction in the influent runoff volume with 80% retained in the system, and 15% recharged to groundwater. The reduction was contributed by the retention capabilities of ST and infiltration capabilities in PB and IT. With the combined mechanisms such as filtration-infiltration, biological uptake from plants and soil and phytoremediation that are incorporated in PB and IT, the system effectively reduces the amount of pollutant concentration wherein the initial mean removal efficiency for TSS is 87%, while an approximate mean removal efficiency of 76%, 46% and 56% was observed in terms of organics, nutrients and heavy metal, respectively. With these findings, the research helps in the further improvement, innovation and optimization of rain garden systems and other facilities as well.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.368-377
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• 2012

This study evaluated the water quality of Yeongsan River by multivariate analysis using the data collected during 2001~2010. Water quality in Yeongsan River could be explained up to 75.2% by four factors, which were included in loading of nutrients (32.021%) and organic matters (17.453%), seasonal variation (14.775%) and microbes (10.951%). The results of cluster analysis were classified into three groups by factor 1 and 2, which has different water quality characteristics. Group 1 included sampling stations located in the upper stream and estuary dyke of Yeongsan River, group 2 included Gwangju 1 and Gwangsan affected by domestic sewage of Gwangju-cheon, and group 3 included sampling stations located in the midstream around the livestock farm and farmland.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1073-1077
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• 2006

급속한 산업화로 인한 오염물질의 증가와 생물서식처의 감소는 수자원과 생태계를 위협하고 있다. 국내의 경우 수자원의 질을 개선하기 위해 '90년대 초부터 하수처리시설 등의 저감시설을 대폭 확충하였으나 현재까지 팔당호 등 주요상수원이 목표수질에 못 미치고 있으며 그 원인은 유입오염물질의 $22{\sim}37%$를 차지하는 비점오염원으로 지목되고 있다. 또한 생태.경관적 가치가 높은 수변지역은 각종 개발로 생물서식처가 급속도로 감소하여 종 다양성 보전 측면에서 대책마련이 시급한 실정이다. 이와 유사한 상황에 직면한 선진외국에서는 '하천회랑(river corridor)' 또는 '토양 및 생태시스템을 포함하는 수역과 육역의 점이(漸移)지대'를 의미하는 이른바 '수변완충지대(Riparian Buffer Zones)'의 오염정화 및 생태조성 효과 등의 연구를 통해 효율적 조성방안을 제시하고 있으며 다양한 형태로 현장에 적용하고 있다. RBZs의 일반적인 기능으로는, 유사나 오염물질의 여과 및 차단(필터링 효과), 영양염류의 저감, 하천변 식생을 통한 수자원의 정화 및 강턱의 안정화, 홍수로 인한 하천침식의 방지, 수변 생물 서식처 제공, 수변 그늘 제공에 의한 수온상승 방지, 심미 교육 위락 공간 제공 등이다. 본 연구에서는 외국의 RBZs(Riparian Buffer Zones)가이드라인을 참고하여 국내실정에 맞는 파일럿 규모의 시험완충지를 설계 및 조성하였다. 시험완충지는 남한강 연안에 초본류, 갈대류, 관목류, 자연식생, 혼합식생 등 5가지 'dry biotope'형태로 설치하여 1년간 계절별로 운영하였다. 또한 실험의 정량화와 다양한 조건변화를 위해 차수막, 위어, 유량.농도 조절장치, 라이시미터 등 보조시설을 설치하였고, 정기적인 모니터링을 실시하였다. 조사결과 외국사례를 살펴보면 RBZs의 적정 폭은 수질정화기능의 경우 $15{\sim}30m$, 생태서식처 기능은 최소 90m이상으로 제시되며, 시험완충지의 수질정화효과는 SS, T-N, T-P, TOC의 평균저감율이 각각 50%이상으로 나타났다. 식생모니터링 결과, 환삼덩굴 등 우점종의 잠식속도는 약 15일이며 갈대와 갯버들의 경우 우기시 인공목책호안과 동일한 침식방지 효과를 보이는 것으로 관찰되어 식생의 주기적인 모니터링과 지역 특성에 적합한 우점종 선정이 매우 중요한 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.302-307
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• 2009

물리적인 조류제어 기술에 해당하는 수류 차단막(이후 차단막)은 유입하천의 수류를 차단 또는 우회시켜 영양염류가 저수지의 유광층으로 공급되는 것을 차단하고 본류 수역으로의 조류 확산을 방지하는 기능이 있어 일본에서는 저수지 녹조제어 대책으로 자주 활용된 바 있다. 그러나 이러한 차단막은 국내 저수지와 같이 홍수시 유입 유속이 크고 수위변동이 심한 환경에서는 설치효과가 검증되지 않아 현장적용에 앞서 수치모의를 통한 효과 검증이 선행되어야 하며, 최적 규모와 위치 선정도 필요하다. 본 연구에서는 수위변동이 심한 국내 저수지 특성을 고려하여 차단막이 수위변화에 따라 상하로 이동할 수 있도록 기존 CE-QUAL-W2(이후W2) 모델의 알고리즘을 수정하고, 대청호에서 다양한 수리 수문조건에서 차단막의 기작과 효과를 예측하기 위해 가뭄년(2001년)과 평수년(2004, 2006년)을 대상으로 각각 모델을 적용하였다. 차단막 설치 예정지점은 소옥천 하류(7 m 깊이)와 댐으로부터 각각 14.9 km, 27.4 km 상류에 위치한 회남대교 아래 지점(10 m 깊이)과 대정리(10 m 깊이)로 가정하고, 모의 시나리오는 차단막을 설치하지 않은 경우(S-1), 소옥천 하류에 단독으로 설치한 경우(S-2), 소옥천과 대정리에 설치한 경우(S-3), 모든 지점에 설치한 경우(S-4)를 비교하였다. 차단막 설치에 따른 수문년 및 계절별 수질개선 효과(S-1에 대한 S-4 농도 저감 비)를 비교한 결과, 대청호에서 녹조문제가 가장 심각했던 2001년 6월$^{\sim}$8월 기간 동안 차단막은 봄-여름에 걸쳐 모든 비교 지점(회남, 댐, 추동, 문의수역)에서 Chl-a 농도를 최저(문의수역) 30%에서 최고(회남수역) 70% 정도 저감하는 효과를나타냈다. 평수년인 2004년과 2006년에는 강우사상에 따라 차단막 설치에 따른 Chl-a의 농도 저감 효과가 지점별로 다르게 나타났으며, 큰 강우사상이 6월, 7월, 8월에 걸쳐 골고루 발생한 2004년에 비해 7월 한 달 동안 집중된 2006년에 설치효과가 크게 나타났다. 수역별로 차단막의 설치효과를 비교해 보면, 유입수의 영향을 직접 받는 회남수역과 추동수역이 댐 앞과 문의수역에 비해 차단막 설치에 따른 Chl-a 농도의 저감 효과가 큰 것으로 나타났다. 그러나, 큰 홍수가 유입할 때 차단막 상류부에 집적된 조류의 일부가 수류의 포획(Entrainment) 기작에 의해 저수지 내부로 유입되는 것으로 확인되어 차단막 효과를 극대화하기 위해서는 홍수 전 차단막 상류부에 집적된 조류의 처리대책이 필요할 것으로 판단된다.