• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.703-713
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• 2012

Three types of aeration system were installed in experimental liquid fertilization tanks to investigate the change of characteristics of pig slurry used as a raw material for making livestock liquid fertilizer. The aeration systems of the reaction tanks were composed of three major part: the air suppling part (blower), the air pipe part, and the air diffuser part. In the first tank (reactor A), the air was supplied from the bottom of the reaction tank through air pipe system connecting air diffuser with commercial ordinary blower. In the second tank (reactor B), the air diffuser was located 10cm above the bottom of the reactor. In the third tank (reactor C), the pure air was supplied with circulating pjg slurry. The oxygen content of pure air was about 90%. The pure air was mixed with pig slurry by mechanically in the air suppling part (blower) and the air pipe part. The agitation effect was highest in the reactor C than other reactors. The contents of SS, COD, T-N and T-P of each samples collected at middle part of all reactors were 8,500, 4,188, 694 and 422mg/L; 9,000, 4,247, 813 and 356mg/L; 8,667, 6,910, 973 and 269mg/L, respectively.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.106-118
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• 2001

The chemistry of porewater and exchangeable nutrients of sediment was determined to define potential influence of sediment nutrients on the water quality and the phytoplankton growth in Taechong Reservoir in March and May of 2000. The sediment-water interface showed almost anoxic state, < 0.5 mg $O_2/l$. Conductivity of the porewater was higher 1.9${\sim}$2.6 fold than that of sediment, and its variation was greater in the shallow water. Eh ranged from -12mV to -148 mV and bulk density from $1.17\;g/cm^3$ to $1.30\;g/cm^3$ and they did not differ among stations. The water content in the sediment ranged from 58% to 72% and organics from 8% to 13%, and they were higher toward the lower part of reservoir. Soil texture was in the order of sand>clay>silt and sandy sediment accounted for 97% of the total sediment. The total bacterial numbers and diatom abundance were high in the downstream of the reservoir. In porewater and exchangeable nutrients of sediment, nitrogen and phosphorus were mostly consist of the particulate form. Inorganic nitrogen was mostly composed of $NH_4$. Nitrogen of porewater was mostly an inorganic form while exchangeable nutrients were composed an organic form. However, phosphorus was composed of dissolved organic fraction in the porewater while inorganic fraction in the exchangeable nutrients. Silicon content of sediment was much exchangeable nutrients with 63%, and it was higher than in the porewater. In summary, the sediments of Taechong Reservoir were mostly composed of organics and assessed to be a eutrophic state.

• Journal of Wetlands Research
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• v.11 no.3
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• pp.9-19
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• 2009

This research addressed nonpoint source (NPS) pollution characteristics in a reclaimed rice paddy field. The paddy has an area of around 2,998 ha and is divided as two sub-watersheds, whose areas are 1,181 ha and 1,817 ha, respectively. Monitoring of hydrologic runoff and NPS pollution was undertaken during three-month period from June to August, 2008. Totally, three sampling trips were made when rainfall depth were 66.0 mm, 23.5 mm, and 23.0 mm, respectively. Generally pollution load increased with the heavier cultivation activity in Korea. Exported pollutants from the rice paddy, including TSS, TN and TP, have same levels as forest discharge. Organic nitrogen is main pattern but it mainly exists in the forms of dissolved organic nitrogen (DON). For phosphorus, dissolved inorganic phosphorus (DIP) takes the main part although part of them is associated with fine particles. This is different compared with other watersheds, where particles-associated phosphorus is the main form.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.19-19
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• 2011

수중방전은 다양한 라디칼을 직접 물 속에서 발생시키기 때문에 수처리 공정에 다양한 응용이 가능하다. 특히, 최근에 선박평형수 등의 살균이 국제적인 이슈가 되고 있고, 2017년까지는 모든 선박에 살균을 위한 수처리 설비가 의무화된다. 본 연구에서는 염분이 있는 수체에서의 방전공정을 연구하고 이를 수처리공정에 적용할 수 있는 방법에 대해 연구하였다. 해수의 경우 전도도가 53mS로 자유로운 전하의 이동이 가능하기 때문에 일반적인 민물방전의 전원과 전극 등으로는 방전을 할 수 없다. 이에 세라믹과 금속의 이중구조로 되어 있는 모세관전극을 개발하여 전도성이 있는 수체에서의 방전을 이루었다. 전원장치로는 60 Hz, 380 V를 1차측에 인가하여 2차측에서 약 3 kV, 10 kW의 파워가 발생하는 12위상차 교류전원장치를 개발하여 사용하였다. 모세관 내부에 전압이 인가되면 전류가 발생하여 joule heating에 의하여 모세관 내부에 기포가 형성된다. 이 때, 전류의 단락이 이루어지면서 고전압쪽에 전하가 축적되며 기포내부의 E-field가 상승한다. 이후 기포 내에서 방전이 개시되며 각종 라디칼을 생성한다. 방전에 의해 생성되는 산화제로는 오존, OH라디칼, 과산화수소 등이 있으며, 해수에서는 Cl-의 결합에 의하여 Cl2 가스가 발생한다. 약 30,000 J/L의 체적에너지에 대하여 생성되는 총염소의 농도는 2.5 mg/L이다. 수중방전의 적용대상으로 선박평형수, 멤브레인과의 결합, 용존기포부상법을 선정하여 적용가능성을 연구하였다. 먼저 선박평형수 살균처리를 위해 해수의 처리유량을 20 lpm으로 유지하고 대장균, 바실러스, 조류(테트라셀미스) 등을 투입하여 전극 12개가 삽입된 12위상차 플라즈마 반응기를 통과시켰더니, 약 30,000 J/L의 체적에너지에 대하여 1일 후의 살균력이 각각 99.99, 99.99, 99.9%의 살균력을 나타내었다. 이는 국제해사기구에서 권장하는 살균수준인 99.9%를 초과하는 수치이다. 플라즈마를 이용한 해수살균공정의 안정적 운전을 위해 후단에 UF멤브레인을 추가하여 잔류생존 미생물을 제거할 수 있다. 이를 위해 플라즈마가 후단의 멤브레인 운전에 미치는 영향을 평가하였다. 카올린과 탄산칼슘을 오염원으로 각각 투입하여 멤브레인으로 처리를 하였을 때, 방전 직후 멤브레인에 걸리는 막간압력차가 약 30% 감소하였는데, 이는 막에 형성된 파울링이 방전에 의해 제거된 것으로 평가할 수 있다. 수중방전은 다양한 산화제를 생성함과 동시에 미세기포를 발생시키는데 이는 수중유기물의 부상분리에 적용될 수 있다. 방전모세관전극의 내부직경을 1 mm로 유지하고, 60 Hz, 교류전원으로 방전한 결과 평균입경 44 um의 기포를 발생시켰고, 이는 일반적으로 용존공기부상법에 사용되는 기포의 크기와 일치한다.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.4
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• pp.31-37
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• 2016

This study was conducted to investigate the effect of OH radicals on organic matter oxidation and suspended solids removal using microbubble as a pre-treatment technique to reduce the organic load of night soil in connection with sewage. The experiment was conducted for three months at HRT 4 hours using pressurized type microbubble generator. The mean SS removal efficiency was achieved 71%. The average removal efficiency of $TCOD_{Cr}$, TBOD, TN and TP were achieved for 51.5%, 47.9%, and 14.7% respectively, as scum and SS were removed by flotation separation. The removal efficiency of soluble organic matters were 25.0%, 17.1% for $SCOD_{Cr}$, SBOD by air microbubble supply. Soluble nitrogen and phosphorus were removed average of 11.9% and 7.4%, respectively. As s result, it was confirmed that soluble organic matters were removed by air microbubble supplied. Generated OH radicals when the microbubble was collapsed, can decompose the soluble organic matters. Therefore, The microbubble flotation process was installed at the front of night soil treatment process, it will contribute to the stable operation of the subsequent biological treatment facility by oxidation of the dissolved organic matters as well as removal of SS by flotation separation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.4
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• pp.252-261
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• 2012

To determine the temporal variations of submarine groundwater discharge (SGD) and SGD-driven nutrients inputs, we measured the seepage rate and the nutrient concentrations of pore water/groundwater in Bangdu Bay of Jeju Island at two and three month intervals from September 2009 to September 2010. The seepage rate of groundwater ranged from 0 to 330 cm/day (average ~170 cm/day) during the five sampling periods, which increased sharply from high tide to low tide due to changes in hydraulic pressure gradient between water table in land and water sea level in the coastal ocean by the tidal cycles. The submarine inputs of groundwater were also relatively higher in summer than in winter. The nutrient fluxes from SGD were about 90~100%, 70~95%, and 65~100% of the total input (except from open ocean waters) for dissolved inorganic nitrogen (DIN), phosphorus (DIP), and silicate (DSi), respectively, potentially supporting about 0.9~33 g $carbon/m^2/day$ of new primary production in Baugdu Bay. Thus, our study suggests that SGD-driven nutrients may play an important role in the eutrophication and biological production in the coastal ocean of Jeju Island.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.4
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• pp.519-534
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• 2019

When the fresh water from the artificial lakes (Ganwolho and Bunamho) were discharged to Cheonsu Bay in summer to prevent the flood over the reclaimed farmland near the lakes, the impact on water qualities (nutrients, organic matters, trace metals) within the bay was investigated through four surveys (June, July, August and October, 2011). Dissolved inorganic nitrogen (DIN) increased about as much as 3-4 times over the whole water column when the freshwater was discharged. And the main species composition of DIN changed from ammonia to nitrate. Dissolved inorganic phosphorus (DIP) decreased as much as 2 times in surface waters, but increased as much as 1.5 times in deep waters, and also silicate concentrations increased as much as 3-4 times in deep waters of the inner bay. The N/P ratios in Chunsu bay seawaters were much higher (2 to 7 times) than the Redfield ratio when the freshwaters were discharged, which indicated the phosphorus limiting in the phytoplankton growth. Dissolved organic carbon (DOC) and nitrogen (DON) increased as much as about 2 times. In addition, particulate organic matters (POC, PON, POP, Bio-Si) increased as much as above 2 times in the surface waters of the inner bay. Trace metals (Fe, Mn, Co, Ni, Cu) increased in the surface waters of the inner bay, but dissolved Cd concentrations decreased as much as 2 times. Therefore, when the contaminated fresh waters from the artificial lakes were discharged into the bay, nutrients, organic matters and trace metals generally increased compared to normal period. Since the phytoplankton bloom occurred in the surface waters of the inner bay, dissolved oxygens at the surface waters were oversaturated and hence hypoxic in the deep waters. Highly enriched nutrients concentrations were found in deep waters of the inner bay, which was accompanied with the hypoxic condition. Finally, the water quality in the inner bay of the Chunsu bay was deteriorated from less than grade 3 in normal periods to grade 5 when the freshwaters from the artificial lakes were discharged in summer.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.148-148
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• 2023

산업 고도화로 인하여 복잡하고 다양한 유기물의 사용량이 증가하였으며, 공공수역 내 새로운 오염물질이 유입됨에 따라 생화학적 산소요구량(BOD) 중심의 수질평가에 한계를 나타내었다. 이후 난분해성 물질을 고려한 유기물관리 정책과 총량관리의 필요성이 제기되었고 국내 하천과 호소에서는 총 유기탄소(TOC)를 유기물 관리지표로 설정하였다. 그러나 부영양 하천과 호소에서 TOC는 외부 부하뿐만아니라 식물플랑크톤의 과잉성장에 의해 증가할 수 있는 항목이므로 TOC 관리정책 추진을 위해서는 유기물의 기원에 대한 파악이 필요하다. 한편, 우리나라와 같이 몬순 기후대에 속한 댐 저수지의 경우 강우시 유입하는 탁수에 의해 다량의 유기물과 인이 유입되기도 하지만 식물플랑크톤의 제한요인 중 광량에 많은 영향을 미친다. 식물플랑크톤의 광합성은 수체 내 유기탄소 내부생성에 매우 중요한 요소이나 점 단위의 실험적 방법을 활용한 유기탄소 순환 해석은 저수지의 시·공간적인 변동성을 고려하기에 한계가 있다. 본 연구의 목적은 금강 수계 최대 상수원인 대청호를 대상으로 3차원 수리-수질 모델을 적용하여 유기탄소 성분 별 유입과 유출, 내부생성 및 소멸량을 평가하고 탁수가 저수지에서의 유기탄소 순환에 미치는 영향을 분석하는데 있다. 유기탄소 물질수지 해석을 위해 AEM3D 모델을 사용하였으며 2018년을 대상으로 입력자료를 구축한 후 보정 및 검정을 수행하였다. 모델은 유기탄소를 입자성, 용존성, 그리고 난분해성과 생분해성으로 구분하여 모의하며 유기물질 성상별 실험결과를 이용하여 입력자료를 구축하였으며 유기탄소순환 해석을 위해 4가지의 탄소성분과 조류 세포 내 탄소의 질량 변화율을 계산하였다. 이를 위해 외부 유입·유출부하율, 수체 내 생성(일차생산, 재부상, 퇴적물과 수체 간 확산) 및 소멸률(POC 및 조류 침강, DOC 무기화, 탈질)을 고려하였으며 탁수의 영향을 분석하기 위해 탁수 포함여부 시나리오를 구성하고 유기탄소 생성 및 소멸기작별 변동성을 비교 분석하였다. 모델은 2018년의 물수지를 적절히 재현하였으며 저수지의 수온 및 탁도 성층구조를 잘 재현해내면서 전반적인 수질을 적절하게 모의하였다. 탁수를 고려하였을 시 연간 TOC 부하량 중 내부기원 부하량은 56% 수준이였으나 탁수를 배제한 경우 내부기원 부하량은 82%로 나타났다. 특히, 연평균 Chl-a 농도가 44~48% 차이가 발생하면서 1차생산량이 약 4배가량 증가하였다. 몬순지역에서의 탁수는 체류시간이 긴 성층 저수지에서 식물플랑크톤 성장제어에 큰 영향을 미쳤으며 전반적인 유기탄소 순환을 해석하는데 있어 매우 중요한 인자로 작용하였다.

• Journal of Applied Biological Chemistry
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• v.54 no.3
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• pp.225-229
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• 2011

This research was carried out to elucidate the impacts of dissolved oxygen (DO) concentration to phosphorus release mechanism from soil into water in lakes. $PO_4-P$ contributed to the growth of the total phosphorus (T-P). $PO_4-P$ was steadily increasing because water was accumulating $PO_4-P$. T-P was closely related to turbidity, pH, and DO. We found that DO had decreased because DO was consumed in organic matter decomposition, and that the resulting anaerobic decomposition occurred whenever water had run out of DO. We also found that pH had decreased sharply by production of organic acid by the anaerobic decomposition and that T-P decreased because a decrease in pH removed turbidity by precipitation. T-P was dissolved without microbial decomposition. This mechanism was of great importance in lakes because phosphorus is released from soil into water.

• Journal of Soil and Groundwater Environment
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• v.10 no.5
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• pp.61-69
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• 2005

Changes in pyrene binding by dissolved and kaolinite-associated humic substances (HS) due to HS adsorptive fractionation processes were examined using purified Aldrich humic acid (PAHA) at different pH (4, 7 and 9). Irrespective of solution pH, molecular weight (MW) fractionation occurred upon adsorption of PAHA onto kaolinite, resulting in the deviation of residual PAHA MW from the original MW prior to sorption. Variation in $K_{OC}$ by bulk PAHA was observed at different pH due to relative contributions of partitioning and size exclusion effects (i.e., specific interactions). For all pH conditions investigated, carbon-normalized pyrene binding coefficients for nonadsorbed, residual fractions $(K_{OC}(res))$ were different from the original dissolved PAHA $K_{OC}$ value $(K_{OC}(orig))$ prior to contact with the kaolinite suspensions. Positive correlations between pyrene $(K_{OC}(res))$ and weight-average molecular weight $(MW_W)$ for residual PAHA fractions were observed for pH 7 and 9. However, such a positive correlation was not found at pH 4 due to the absence of the dramatic fractionation observed for high pH conditions (i.e., exclusive fractionation with respect to higher MW), suggesting that actual MW distribution pattern is more important for sorption-fractionated HS than the composite MW value. For adsorbed PAHA, conformational changes of PAHA upon adsorption seem to be important for the extent of pyrene binding. At relatively high pH (7 and 9), lower extent of pyrene binding was observed for adsorbed PAHA versus nonadsorbed PAHA. The conformation effects were more pronounced at higher pH.