• Journal of Advanced Marine Engineering and Technology
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• 제25권5호
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• pp.1098-1107
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• 2001

This study is to develop the pretreatment for the excess and digested sludge by elector-coagulation and dewatering. Electrocoagulation is applied to excess and digested sludge before transferring to the pistion type for dewatering. Piston type filter press as a laboratory scale plant was used to estimate the dewaterability. MMD of excess sludge was increased from initial diameter of particles ($34.16{\mu}m$) to the 87%($64.01{\mu}m$) after electrocoagulation. Al electrode is more effective than Fe electrode for the dewaterabiltity of excess sludge Electrodewatering after electrocoagulation as pretreatment makes the water content of sludge cake 50~60 wt%.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1992-1997
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• 2003

This study is to develop the pretreatment for the excess and digested sludge by electro-coagulation and dewatering. Electrocoagulation is applied to excess and digested sludge before transferring to the piston type press for dewatering. Piston type filter press as a laboratory scale plant was used to estimate the dewaterability. MMD of excess sludge was increased from initial diameter of particles(34.16 ${\mu}m$) to the 87%(64.01 ${\mu}m$) after electrocoagulation. AI electrode is more effective than Fe electrode for the dewaterability of excess sludge. Electrodewatering after electrocoagulation as pretreatment makes the water content of sludge cake $50{\sim}60$ wt%.

• 상하수도학회지
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• 제19권5호
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• pp.537-546
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• 2005

This study was carried out to evaluate EPS and SMP variation of sludge and effluent in nitrification and denitrification process with zeolite addition, a possible reduction of effluent DOC by URC(Ultra Rapid Coagulation) process. As a biological wastewater treatment result, EPS formation of both aeration and anoxic sludges are not affect by SRT variation. However, EPS concentration of sludges is higher in aeration tank than in anoxic tank by 6~8 mg EPS/ g VSS. Linear relationship between SMP to DOC indicates that SMP of bulk solution contributes to most of the biological treatment effluent DOC. DOC and turbidity removal efficiency was more improved with URC process than in a conventional coagulation. For pretreatment of UF filtration DOC removal was advanced by URC process than only UF filtration.

• 상하수도학회지
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• 제31권4호
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• pp.289-296
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• 2017

Pulp and paper industry produces large volumes of wastewater and residual sludge waste, resulting in many issues in relation to wastewater treatment and sludge disposal. Contaminants in pulp and paper wastewater include effluent solids, sediments, chemical oxygen demand (COD), and biological oxygen demand (BOD), which should be treated by wastewater treatment processes such as coagulation and biological treatment. However, few works have been attempted to predict the treatment efficiency of pulp and paper wastewater. Accordingly, this study presented empirical models based on experimental data in laboratory-scale coagulation tests and compared them with statistical models such as artificial neural network (ANN). Results showed that the water quality parameters such as turbidity, suspended solids, COD, and UVA can be predicted using either linear or expoential regression models. Nevertheless, the accuracies for turbidity and UVA predictions were relatively lower than those for SS and COD. On the other hand, ANN showed higher accuracies than the emprical models for all water parameters. However, it seems that two kinds of models should be used together to provide more accurate information on the treatment efficiency of pulp and paper wastewater.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.415-420
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• 2001

Water usage in the semiconductor industries is dramatically increased by not only using bigger wafer from 8 inches to 12 inches but also by adapting new process such as Chemical Mechanical Planarization (CMP) process invented by IBM in late '80. However, The document published by International Semiconductor Association suggests the decreasing ultra pure water (UPW) use from 22 gallon/in$^2$in 1997 to 5 gallon/in$^2$ in 2012. The criteria will possibly used as exporting obstacle in the future. Generally, Solid content of CMP slurry is about 15wt%. The slurry is diluted with UPW before fed to a CMP process. When the slurry is discharged from the process as waste, it contains 0.1~0.6wt% of solid content and 9~10 at pH. The CMP waste slurry is discharged to stream with minimum treatment. In this study, to find optimum condition of coagulation for water recovery from the waste CMP slurry various condition of coagulation were examined. After coagulation far 0.1 wt% solid content of waste CMP slurry, the sludge volume was 10~15% after 30 min of sedimentation time. For the 0.5 wt%, sludge volume was 50~55% after one hour of sedimentation time. For more than 80% of water recycling, the solid content should be in the range of 0.1 to 0.2wr%. Based on the result of the turbidity removal, the Zeta Potential and the analysis of heavy metals, the optimum condition for 0.1 wr% of waste CMP slurry was with 20 mg/L of PACI at 4 to 5 of pH. The result showed that the optimum conditions fer the 0.1 wt% waste CMP slurry were 100mg/L of Alum at 4~5 of pH, 100 mg/L of MgCI$_2$at pH 10 to 11 and 100 mg/L of Ca(OH)$_2$at pH 9 to 11, respectively.

• 상하수도학회지
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• 제16권6호
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• pp.733-740
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• 2002

The effects on dewaterability and settlability of wastewater sludge according to acid and ultrasonic pretreatment which was expected to change ECP (exocellular polymers) compounds in the sludge and bulk solution was investigated. Though ECP which attached to the sludge could stimulate coagulation of sludge particles by bridging effect, but ECP in the bulk solution deteriorated dewaterability and settlability of the sludge on the contrary. That is as the pH of the solution was decreased to 3 gradually by acid treatment, proportionally ECP in the bulk solution was attached to the sludge flocs and resulted in improvement of dewaterability and settlability of the sludge. In case of ultrasonic pretreatment, with proportional to the intensity and duration of ultrasonic application, ECP was detached and extracted from sludge flocs and these phenomena deteriorated dewaterability and settlability. Also because of the increasement of minute sludge particles according to ultrasonic, dewaterability became so much the worse.

• 상하수도학회지
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• 제31권1호
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• pp.103-114
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• 2017

A membrane bioreactor by sequentially alternating the inflow and by applying a two-stage coagulation control based on pre-coagulation was evaluated in terms of phosphorus removal efficiency and cost-savings. The MBR consisted of two identical alternative reaction tanks, followed by aerobic, anoxic and membrane tanks, where the wastewater and the internal return sludge alternatively flowed into each alternative reaction tank at every 2 hours. In the batch-operated alternative reaction tank, the initial concentration of nitrate rapidly decreased from 2.3 to 0.4 mg/L for only 20 minutes after stopping the inflow, followed by substantial release of phosphorus up to 4 mg/L under anaerobic condition. Jar test showed that the minimum alum doses to reduce the initial $PO_4$-P below 0.2 mg/L were 2 and 9 mol-Al/mol-P in the wastewater and the activated sludge from the membrane tank, respectively. It implies that a pre-coagulation in influent is more cost-efficient for phosphorus removal than the coagulation in the bioreactor. On the result of NUR test, there were little difference in terms of denitrification rate and contents of readily biodegradable COD between raw wastewater and pre-coagulated wastewater. When adding alum into the aerobic tank, alum doses above 26 mg/L as $Al_2O_3$ caused inhibitory effects on ammonia oxidation. Using the two-stage coagulation control based on pre-coagulation, the P concentration in the MBR effluent was kept below 0.2 mg/L with the alum of 2.7 mg/L as $Al_2O_3$, which was much lower than 5.1~7.4 mg/L as $Al_2O_3$ required for typical wastewater treatment plants. During the long-term operation of MBR, there was no change of the TMP increase rate before and after alum addition.

• 한국산학기술학회논문지
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• 제19권8호
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• pp.105-114
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• 2018

전기응집 (Electro-coagulation)을 활용한 분리 막 생물반응기 (Membrane Bio-Reactor) 공정의 막 오염 저감 현상을 확인하고 이를 해석하고자 하였다. 전기응집의 주요 운전 인자인 전류밀도와 접촉시간 변화가 활성슬러지 혼합액의 막 여과에 미치는 영향을 관찰하고 전기응집 과정에서 발생하는 수산화금속염이 막 오염에 미치는 역할에 대해 연구하였다. 전류밀도를 $10A/m^2$으로 높게 유지한 경우에는 전기응집 시간이 증가하여도 막 오염 감소 효과가 크지 않은 반면 $2.5A/m^2$의 낮은 전류밀도 하에서는 전기응집 시간이 증가하면 추가적인 막 오염 감소가 관찰되었다. 즉, 막 오염을 감소시키는 전류밀도와 접촉시간의 곱이 전체 막 오염 저감 정도를 지배하고 있음을 확인하였다. 또한 주어진 전류밀도와 인가시간에서 입도분포는 크게 변화하지 않은 것으로 나타나 콜로이드 입자와 막 오염 저감과는 큰 관련성이 없는 것으로 판단되었다. 그러나 전기응집을 통해 생성된 수산화알루미늄 (인산알루미늄)이 막 여과 과정에서 동적 막 (Dynamic Membrane)을 형성하여 막 오염 현상을 완화하는 것으로 확인되었다. 전기응집에서 발생한 수산화금속염이 막 표면에 동적 막을 형성하고 이로 인해 유입수의 입자성분이 직접 막 표면과 내부에 침적되는 것을 방해하고 동적 막에 주로 쌓이게 함으로써 막 오염이 감소된 것이다. 본 연구에서 밝힌 수산화금속염에 의한 동적 막의 역할은 전기응집을 활용한 MBR 공정의 후 막 오염 감소 메커니즘을 해석하는데 중요한 역할을 한다고 결론지을 수 있다.

• 환경위생공학
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• 제17권1호
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• pp.12-19
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• 2002

This study was carried out to investigate the optimal condition for granite particle coagulation process by using various chemical coagulation agents. The coagulation of a suspended granite particle was monitored by using various different coagulants, such as $Al_2(SO_4)_3{\cdot}14H_2O,{\;}FeCl_3{\cdot}6H_2O,{\;}SA-solution(KOH{\;}+{\;}Al(OH)_3{\;}+{\;}K_2CO_3{\;}mixture)$ and jade particle. To accomplish this study, analysis of water quality, removing Turbidity and Packing Density were measured with jar-tester. In the results of this experiment, it was found that the removal rate of the granite particle was increased with the decrease of the pH of the sludge. The turbidity(NTU) at the above coagulants was reduced from 95% to 98%. Removed of Turbidity and Packing Density was more efficiency to the SA-solution than others.

• 자원리싸이클링
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• 제13권4호
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• pp.17-22
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• 2004

본 연구는 하수처리장에서 발생되는 농축슬러지의 처리방법에 대해 진행하였다. 방사선을 15 kGy 조사하였을 때 농축슬러지에 존재하는 일반세균 및 대장균을 99% 이상 제거, 유기물 분해등 소화조에서 일어나는 공정을 대체 할 수 있다. 폐수산자원인 불가사리를 가공하여 제조한 물리개량제를 첨가하여 응집공정의 효율을 높이고 아울러 함수율 10% 이상의 저감효과를 얻을 수 있다.