• 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.

• 한국환경과학회지
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• 제8권3호
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• pp.363-369
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• 1999

This study aimed to elucidate the relationship between theoretical parameters affecting the coagulation process and the real coagulation phenomenon applied to the dye wastewater. Emphasis was placed on the effective removal of the suspend particulates. Parameters studied in this study are pH, coagulant concentration and surface potential. Optimal dosages of coagulants by the measurement of the zeta potential at lower then $25^{\circ}C$ are 5\times$10^P-3}$ M of $FeCl_3 and 1.4\times10^{-6}M of Fe_2(SO_4)_3$. The results were well agreeded with the separate Jar-test results. Emphasis was also placed on the relationship between water quality and the content of SS. It was found that the COD and DOC were reduced to 65% and 85%, respectively. The turbidity at the above condition was reduced from 300 NTU to 0~1 NTU. Efforts were made to clarify the behavior of the suspend solid as affecting the water quality. 12,000~13,000 particles/10mL in $1~50\mu$m size range particulates in the raw wastewater were reduced to 300 particle/10mL in the same range after treatment. This research has proposed the methodology to find out the optimal condition of coagulation for small scale wastewater treatment plant or chemical coagulation process.

• 한국환경과학회지
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• 제20권6호
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• pp.767-773
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• 2011

The objectives of this research are to investigate the proper coagulation conditions which are a type and doses of coagulants, mixing conditions (velocity gradients and mixing times), pH and so on through Jar-test, to evaluate the flux variations, permeate, backwashing according to characteristics of pretreatment of the wastewater by means of MF membranes for river maintenance water reuse. The effluent water from B-city K-sewage treatment plant are used for this research. Turbidity and suspended solids(SS) are 14.2 NTU and 10.4 mg/L respectively. This condition causes fouling for membrane process. The flux decline could be reduced when coagulation pretreatment was carried out. Optimal coagulations PAC which are commonly used in the sewage treatment plant was observed in this research. The results indicate that an optimal coagulation dose and pH are 80 ppm and pH of 7 respectively, but coagulation efficiency was lower at strong acid or strong base. Results showed that continuous and steady operations in membrane separation process by means of the effective removal of organic matter and turbidity with coagulation pretreatment of sewage secondary effluent were achieved.

• 상하수도학회지
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• 제20권2호
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• pp.235-244
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• 2006

A PCF(Pore Controllable Fiber Filter) process was applied as a pretreatment of water treatment for reduction of turbidity. The experimental results obtained from the PCF showed that the removal efficiency of turbidity without coagulation was around over 70 percent. However, the removal efficiency of turbidity by the coagulation-PCF process was high as much as over 95%. Thus, the coagulation pretreatment was required for the better operation of the PCF. The SEM (Scanning Electron Microscope) images of fiber before and after filtration showed that the filtration mechanism of PCF filter is both controlling attachment mechanism and Sieving mechanism through fiber pore. For the coagulation-PCF process, optimum dosage of coagulant was needed for the economical operation, and for this, determining the optimum dosage by using a filter column test. Also only 16mg/L of alum was used to obtain high algae removal efficiency over 90%. Therefore, it can be concluded that coagulation-PCF process is very effective pretreatment process for algae removal.

• 한국환경과학회지
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• 제5권2호
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• pp.203-210
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• 1996

To improve coagulation characteristics and to reduce dossage of chemicals in watertreatment, polyaluminium sulfate was manufactured by reaction of polymerization between aluminium sulfate and sodium aluminate. As the results of affirmation and performance test, the yield of product was about 24% from molecular cut on levels by ultrafilteration method. The type of molecular is nearly affirmated as a kind of complex like AIm(OH)n(3m-n)+ from Scanning Electron Microscopy (S.E.M.) and X-ray diffraction test. Since the synthesized polymer was supposed to be quasi, further study for stabilization was required.

• 상하수도학회지
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• 제18권6호
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• pp.742-747
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• 2004

Solid-liquid separation of swine wastewater was conducted using bentonite as coagulant. During the separation experiment, coagulation efficiency was also investigated. To determine optimal bentonite dose, 0.1, 0.2, 0.4, 0.8, and 1.6% (w/v basis) of bentonite was dosed. Suspended solid removal efficiency was 87-98% at whole bentonite dosage. But sediment volume was increased, and settling velocity was decreased at excessive bentonite dosage. Therefore optimal bentonite dosage was evaluated around 0.2-0.4%. In the test to determine optimal pH, coagulation using bentonite was performed at pH 3, 4, 5, 6, and 7. At lower pH suspended solid removal efficiency was increased. However, sediment volume was also increased and phosphorus release was observed. Thereby optimal pH for bentonite coagulation might be appeared in the range of 6-7.

• Environmental Engineering Research
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• 제15권2호
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• pp.63-70
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• 2010

In this study, the response surface method and experimental design were applied as an alternative to conventional methods for the optimization of coagulation tests. A central composite design, with 4 axial points, 4 factorial points and 5 replicates at the center point were used to build a model for predicting and optimizing the coagulation process. Mathematical model equations were derived by computer simulation programming with a least squares method using the Minitab 15 software. In these equations, the removal efficiencies of turbidity and total organic carbon (TOC) were expressed as second-order functions of two factors, such as alum dose and coagulation pH. Statistical checks (ANOVA table, $R^2$ and $R^2_{adj}$ value, model lack of fit test, and p value) indicated that the model was adequate for representing the experimental data. The p values showed that the quadratic effects of alum dose and coagulation pH were highly significant. In other words, these two factors had an important impact on the turbidity and TOC of treated water. To gain a better understanding of the two variables for optimal coagulation performance, the model was presented as both 3-D response surface and 2-D contour graphs. As a compromise for the simultaneously removal of maximum amounts of 92.5% turbidity and 39.5% TOC, the optimum conditions were found with 44 mg/L alum at pH 7.6. The predicted response from the model showed close agreement with the experimental data ($R^2$ values of 90.63% and 91.43% for turbidity removal and TOC removal, respectively), which demonstrates the effectiveness of this approach in achieving good predictions, while minimizing the number of experiments required.

• 대한관절경학회지
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• 제16권2호
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• pp.121-127
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• 2012

목적: 관절경 수술을 시행 받은 환자의 항응고 요법이 응고능에 미치는 영향과 대표적 항응고 약물 사이에 차이가 있는지 알아보기 위하여 항응고 약물 중 두 종류를 선택하여 사용한 환자들의 혈액 응고 검사를 수술 전후에 시행하여 수술 전 후 및 두 약물 간에 차이가 나타나는지에 대해 알아보았다. 대상 및 방법: 관절경 수술을 시행한 47예의 슬관절 혹은 고관절 환자를 대상으로 하였으며 환자군을 무작위로 enoxaparin과 rivaroxaban을 사용한 두 그룹으로 나누어 수술 전 및 수술 후 5일째 응고 검사를 시행하여 수술 전후 및 두 약물간의 결과를 비교하였다. 결과: 수술 전 시행한 응고 검사에서는 두 그룹간의 유의한 차이가 없었으나(P>0.05) 수술 후 5일째 시행한 응고 검사에서는 prothrombin time-international normalized ratio (PT-INR), activated partial thromboplastin time (aPTT)에서 증가 소견을 보였고 특히 rivaroxaban 환자군의 수치가 증가한 것으로 나타났다(P<0.05). 결론: 관절경 수술의 약물을 통한 항응고 요법은 혈액 검사를 통한 결과에서 출혈 경향 면에서 안전한 범위에서 수술전과 비교하여 통계적으로 유의한 차이를 보였으나 rivaroxaban을 사용한 환자 군에서 응고능의 정상 범위를 넘어서는 환자가 있어 rivaroxaban의 사용에 주의를 요할 것으로 생각된다.

• Neonatal Medicine
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• 제17권1호
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• pp.132-135
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• 2010

미숙아에서 비정상적인 출혈의 대부분은 감염과 관련되어 발생하는 후천성 응고 장애가 원인인 경우가 많으므로 혈우병과 같은 유전응고장애질환은 간과되기 쉽다. 저자들은 반복되는 출혈 경향을 보인 재태 기간 31주 1일, 1,880 g으로 출생한 미숙아에서 혈우병 A를 진단하고 VIII인자 보충을 통해 치료하였기에 보고하는 바이다.

• 한국해양환경ㆍ에너지학회지
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• 제3권1호
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• pp.62-69
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• 2000

본 연구는 담수조류의 대량 번식에 따른 정수장의 여과막 박힘, 어류의 대량폐사 등 각종 피해를 최소화하기 위하여 응집제를 이용한 응집-여과공정을 녹조제거시스템에 적용하기 위한 것이다. 응집-여과 공정에서 최적의 응집상태를 결정하기 위하여 시료로는 낙동강 원수를 사용하였고 Jar test와 실험실용 반응기를 사용하여 알칼리도, 탁도, Chl-a, pH를 측정하였다. 응집시간, 응집제 주입량, 드럼필터 회전속도 그리고 Chl-a는 각각 5min, 5mg/l, 3rpm 그리고 90㎍/l의 조건에서 높은 조류제거율을 보였다. Alum을 사용하였을 때의 조류 및 탁도 평균제거율은 50～60%, 30～50%이었고, PAC는 Chl-a의 제거율이 Alum보다 약 20% 더 좋은 효율을 보였다.