• Advances in environmental research
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• 제3권4호
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• pp.293-306
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• 2014

The present study primarily focuses on the evaluation of the comparative effect of chemical coagulation and ultrasonication for elimination of aromatic amines (AAs) present in anaerobically pretreated textile wastewater containing different types of dyes including azo dyes. Color and COD reduction was also monitored at the optimized conditions. The production of AAs was measured spectrophotometrically in the form of total aromatic amines (TAAs) and also verified with high performance liquid chromatography (HPLC) selectively. A composite coagulant, magnesium chloride (MC) aided with aluminium chlorohydrate (ACH) in an equal ratio (MC + ACH) was utilized during the coagulation process, which yielded 31% of TAAs removal along with 85% of color and 52% of COD reduction. At optimized power (200 W) and sonication time (5 h), an appreciable TAAs degradation efficiency (85%) was observed along with 51% color reduction and 62% COD removal using ultrasonication. The chromatographic data indicate that sulphanilic acid and benzidine types of aromatic amines were produced after the reductive cleavage of utilized textile dyes, which were effectively mineralized after ultrasonication. The degradation followed the first order kinetics with a correlation coefficient ($R^2$) of 0.89 and a first-order kinetic constant (k) of $0.0073min^{-1}$.

• 대한환경공학회지
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• 제34권9호
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• pp.590-596
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• 2012

고도응집 공정은 DBP 전구물질인 NOM을 제거하는 최적기법이다. 본 연구에서는 낙동강 원수를 대상으로 $FeCl_3$, alum, PSOM 및 PACl 응집제를 대상으로 고도응집 공정의 적용시 가장 효과적인 응집제와 응집조건을 DOC, THMFP, HAAFP 및 제타전위 변화를 중심으로 평가하였다. 탁도 제거율은 고도응집을 적용시 기존응집에 비해 제거율의 상승은 없었으며, 일정 응집제 주입량 이상에서는 제거율이 더욱 저하되었으나 DOC, THMFP 및 HAAFP 제거율은 응집제 종류별로 기존응집에 비해 각각 13~18%, 9~18% 및 9~18% 정도 증가하였다. 응집 pH 변화에 따른 탁도 제거특성은 $FeCl_3$와 PACl이 pH 4~10 범위에서 비교적 높은 탁도 제거율을 나타내었고 alum과 PSOM의 경우는 pH 5~8의 범위에서 안정적인 제거율을 나타내었다. DOC는 4종의 응집제 모두 pH 5~7 범위에서 안정적인 제거율을 나타내었다. 고도응집 공정을 적용시 1 kDa 이하 및 10 kDa 이상의 용존 유기물질의 제거율은 각각 11~21% 및 16% 정도 기존응집 공정에 비해 증가하였으며, 소수성 및 친수성 유기물질의 제거율은 각각 27~38% 및 11~15% 정도 증가하였다. 낙동강 원수의 고도응집에 가장 효과적인 응집제로는 $FeCl_3$로 나타났으며, 다음으로 PSOM, PACl 및 alum 순이었다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1997년도 특별강연 및 추계학술발표 개요집
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• pp.184-193
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• 1997

Aluminium and aluminium alloys have the high electrical and heat conductivity. It gives rise to difficulties for a choice of electrodes material for their contact electric welding. This paper describes the investigations performed to solve the above problem. The purpose of this investigation was to obtain dispersion-hardening alloys by the internal oxidation method, to optimize their contents and treatment modes, to produce electrodes of these alloys and to test them. The strengthing effect of alloys with oxide particles depends on their size stability at high temperatures. Despite of the fact, that oxides are the most stable of all the non-metallic phases their coagulation takes place. Based on the early results, we chose two types of alloys, first No. 1 Cu - 0,4%Al and second No. 2 Cu - 0,2%Be for production of electrodes. These alloys had not additional alloying elements. These alloys were prepared as 1 mm plates and flake-formed 200 m thick, and also No. 1 as a powder of size 100 mkm (received from Korea). The large samples for electrodes were produced by three methods : explosive welding method, dynamic one including the explosion compression of electrode blank and the quasi-dynamic method including the high-speed compression of dense briquest and the further hot extrusion of a rod.

• 대한환경공학회지
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• 제28권1호
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• pp.34-41
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• 2006

본 연구에서는 원수의 수질 변화 중 SC에 대한 영향 인자와 이런 인자가 streaming current(SC) 및 set point(SP)에 미치는 영향 정도를 조사하였다. 서울시 구의 취수장의 전염소 처리되지 않은 원수를 실험에 사용하였다. Pilot scale 실험을 통하여 원수 수질 변화에 따른 SC의 변화와 응집제인 poly aluminium chlorides(PACs)의 변화에 따른 SC의 변화를 알아보았다. 또한, 탁도와 용존유기탄소(dissolved organic carbon, DOC)의 처리 효율에 대한 인자들의 영향에 대하여 평가하였다. 실제 한강 원수를 대상으로 일정 기간 동안 원수의 수질과 SC의 변화를 관찰한 결과, SC와 전기전도도가 높은 상관성을 보임을 알 수 있었다. SC를 기준으로 응집 처리한 결과, 최적 응집 조건으로 대표되는 SC, 즉 SP가 연구기간 동안 우기에서 건기로 변화함에 따라 감소하는 경향을 보였다. 특히 원수의 수질이 저탁도 일 때, 탁도에 비해 전기전도도가 SC에 미치는 영향이 상대적으로 증가하는 것으로 나타났다. 전기전도도가 SC와 SP 그리고 응집에 미치는 영향에 대한 실험을 수행한 결과 전기전도도가 증가할수록 SP는 감소하였고, 단위 SC 증가를 위해 주입된 응집제의 양은 점점 증가하였다. 이상의 결과를 통해 볼 때, 응집 공정의 최적 제어를 위해 SC를 이용한 응집 제어는 매우 효율적으로 수행할 수 있었으며, 특히 SP 설정을 위해서는 원수의 수질 특히 전기전도도의 실시간 측정을 고려할 필요가 있는 것으로 나타났다.

• 대한환경공학회지
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• 제27권6호
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• pp.581-589
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• 2005

최근, 하 폐수 처리에 있어서 처리수의 보다 나은 수질과 엄격한 기준의 만족을 위해 기존의 공정외에 덧붙여 막분리 공정이 이용되고 있다. 그러나, 수처리 과정에서 막분리 공정의 사용은 막의 막힘 현상과 용존 유기오염물 제거의 어려움 등의 문제점이 있다. 본 연구에서는 막분리 공정에 응집제 alum과 PAC을 이용한 응집공정을 첨가하여 막 투과유속과 처리효율을 증가시켰다. 그리고 응집제 주입효과와 최적운전조건은 투과유속, 누적부피, 막의 총저항, 입자크기, 용존성 유기오염물, 용존성 알루미늄, 처리수의 수질을 분석하여 연구하였다. alum 응집에 비교해 PAC 응집은 큰 입자를 형성하여 여과 매체의 막힘현상을 줄이고 높은 투과유속과 누적 부피량을 보였다. 또한 PAC 응집에서 낮은 용존 유기오염물과 용존성 알루미늄은 투과유속 감소율을 낮추었다. $0.2\;{\mu}m$ 막 사용시 케이크여과의 모습을 보였으며, $0.45\;{\mu}m$ 막 사용시 순환운전으로 인한 플럭 깨짐 현상으로 공극보다 작은 플럭의 투과가 발생하여 투과유속이 계속 감소하고 막의 총저항이 증가하는 모습을 보였다. PAC과 alum 모두 약 $300{\pm}50\;mg/L$가 최적 응집주입량이었으며, PAC 응집과 $0.2\;{\mu}m$ 막 사용시 처리 효율이 가장 높고, $0.45\;{\mu}m$ 막 사용시 투과수량이 가장 많았다. 처리 효율은 탁도 99.8%, SS 99.9%, $BOD_5$ 94.4%, $COD_{Cr}$ 95.4%, T-N 54.3%, T-P 99.8%이었다.

• 상하수도학회지
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• 제23권4호
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• pp.397-406
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• 2009

This study was conducted to monitor the floc sizes forming in the mixing zone in the water treatment plant. The dosing amount of poly aluminium chloride(PAC) was determined by particle dispersion analyzer(iPDA) in the lab and field scale test. During a field test period, PAC coagulant was used and the raw water was taken from Nakdong river. PAC wad diluted to activate the coagulant, leading to bring the more homogeneous dispersion in the shorter time. To monitor the floc sizes, the unit of floc size index(FSI) was used. With increasing of raw water turbidity, FSI value was increased. Also, the increased dosing amount of PAC brought the increased FSI and with overdosing of coagulant was in turn decreased. When the PAC was fed into the raw water after dilution in a field scale test, the width of FSI was narrower compared with the feeding of the mother liquor of PAC, implying that the formed flocs are denser and more uniform sizes. The width of FSI in average was varied on depending on the basicity of coagulant. Also, dF value, fractal dimension was evalued with the different coagulants, showing from 2.01 to 2.03. On-line floc monitor was effective for the optimal dosing in the drinking water plant.

• 상하수도학회지
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• 제22권6호
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• pp.633-640
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• 2008

In this research, the $3.6m^3/day$ scale pilot plant consisting preozonation, coagulation, flocculation, and ceramic membrane processes was operated for long term period to evaluate the validity of ceramic membrane filtration process for treating lake water containing high concentration manganese. The higher concentration of dissolved manganese($Mn^{2+}$) was effectively oxidized to the bigger insoluble colloidal manganese ($MnO^2$) by 1~2 mg/L ozone. The colloidal manganese reacted with coagulant (poly aluminium chloride, PAC) and then formed the big floc. Ceramic membrane rejected effectively manganese floc during membrane filtration. Dissolved organic carbon(DOC) removal was dependent upon $Mn^{2+}$ concentration. While average $Mn^{2+}$ concentration was 0.43 and 0.85 mg/L in raw water, DOC removal rate in preozonation was 26.5 and 13.5%, respectively. The decrease rate of membrane permeability was faster without preozonation than with preozonation while membrane fouling decreased with NOM oxidation by ozone. In conclusion, raw water containing high concentration of manganese can be effectively treated in preozonation-coagulation-ceramic membrane filtration system.

• 대한화학회지
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• 제57권3호
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• pp.316-321
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• 2013

Electrocoagulation (EC) technique is applied for the treatment of wastewater containing heavy metals ions such as nickle (Ni), lead (Pb) and cadmium (Cd) by using sacrificial anodes corrode to release active coagulant flocs usually aluminium or iron cations into the solution. During electrolytic reactions hydrogen gas evolve at the cathode. All the experiments were carried out in Batch mode. The tank was filled with synthetic wastewater containing heavy metals and efficiency of electro-coagulation in combination with aluminum and iron electrodes were investigated for removal of such metals. Several parameters, such as contact time, pH, electro-coagulant concentration, and current density were optimized to achieve maximum removal efficiency (%). The concentrations of heavy metals were determined by using Atomic Absorption Spectroscopy (AAS). It is found that the electro-coagulation process has potential to be utilized for the cost-effective removal of heavy metals from wastewater specially using iron electrodes in terms of high removal efficiencies and operating cost.

• 한국물환경학회지
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• 제30권3호
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• pp.311-318
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• 2014

The purpose of this study is to investigate the effect of various types of coagulant on dewaterability and settleability of sewage sludge for the application of dewatering process. Cationic organic coagulants and inorganic coagulants of the aluminium base were used; PAC (Poly Aluminium chloride, $Al_2O_3$ 17%) and C-210P (0.2%). After Jar test, PAC 26 mg/L and 0.2% C-210P 55 mg/L was decided as the optimum concentration of the coagulant according to zeta potential measurement. pH, alkalinity and viscosity were measured in all experiments and the data on sedimentation characteristics is analyzed by SDI, SVI sedimentation rate and solid flux. The SRF(Specific Resistance of Filtration) experiment was conducted with the result of single and dual injection system as the dewaterability experiment. As a result, the organic coagulant making large floc has good characteristics of sedimentation and agglutination. Also, it is observed that the organic coagulants injection has a better dewaterability efficiency of coagulants under the condition of the lowest SRF value, followed by dual and inorganic coagulants injection.

• Environmental Engineering Research
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• 제23권2호
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• pp.210-215
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• 2018

Coal seam gas (CSG) water, to be discharged, has been usually treated in reverse osmosis (RO) plants which require extensive and expensive pre-treatment. However, current low gas prices have been a great driver for relevant industries to seek for alternative cost-effective technologies in the aspect of its beneficial use and fit-for-purpose usable water production. In this paper, a combined system with a two-stage pore control fiber (PCF) filtration and a RO system was designed and tested for CSG water treatment. Also, a coagulation reactor was placed in front of the PCF to further enhance suspended solid removal. More than 99% of SS were removed through the PCF filtration while organic, total nitrogen and total phosphorous were mostly removed by the RO system. Especially along with a decrease in conductivity, the total dissolved solid derived from salts was mainly removed in the RO system. Having $OH^-$ undetected, $HCO_3{^-}$ was found to be a dominant compound and its removal efficiency was 97-98% after the RO treatment. And a Fe(III) type of Polytetsu, which was the first to be tested in this paper, was found to be a better option than a Al(III) type of Poly Aluminium Chloride due to its greater coagulation efficiency and applicability at a broader range of pH than the Al(III) type. In addition, there was no noticeable change in oxidation reduction potential, suggesting that an additional process is required to oxidize non-ionic organic carbons (detected as total organic carbon).