• 환경위생공학
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• 제18권1호
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• pp.41-50
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• 2003

Traditionally the supernatant after chemical treatment of metal acid wastewater is discharged in environment. The supernatant can be used as a coagulant as it contains effective metals. The aim of this study is to investigate the feasibility of treatment of dyeing wastewater using the supernatant after treatment by magnesium hydroxide and dolomite($Ca{\cdot}Mg(CO_3)_2$), of acidic metal wastewater. In dyeing wastewater treatment with the supernatant, optimum pH and dosage were determined. COD, turbidity and color were analyzed to evaluate the performance of treatment. In the case of magnesium hydroxide, the optimum dosage was 10%(v/v) for supernatant A and 3%(v/v) for supernatant B. Color, turbidity and COD removal was 99~100%, 85~97% and 43~53%, respectively. In the case of dolomite, the optimum dosage was 10%(v/v) for supernatant A and 3% for supernatant B. Color, turbidity and COD removal was 96~99%, 62~9l% and 52~53%, respectively.

• 공업화학
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• 제20권3호
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• pp.301-306
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• 2009

본 연구에서는 냉연도금공장의 각 단위공정에서 발생되는 폐수를 미생물을 이용하여 안정하게 처리하기 위하여 각 폐수의 특성파악과 처리조건을 도출하고자 하였다. 발생되는 폐수 중 알칼리성폐수가 전체폐수의 64%를 차지하였으며, 산중금속함유폐수는 30%를 차지했다. 탈류폐액의 COD는 53890 mg/L로 전체 폐수발생량의 0.03%에 불과함에도 불구하고 COD의 53%를 유발하고 있었으며, COD의 94%는 SCN에 의해 기인하였다. 혼합폐수를 미생물로 처리할 때 혼합폐수 중 SCN농도가 200 mg/L 이하일 때 제거가 용이하였다. 반면 COD 유발물질은 400 mg/L 이하가 되더라도 처리효율이 미흡하였다. 이는 탈류폐액 중에는 난분해성 유기물질이 다량 함유되어 있기 때문이라 판단된다. 혼합폐수를 처리할 때 초기에 pH가 7.33이었지만 8 h 후에는 7.99로 상승하였다. 이는 탈류폐액에 함유된 SCN이 박테리아에 의해 분해될 때 발생되는 암모니아에 의해 기인한 것으로 사료된다.

• 상하수도학회지
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• 제12권3호
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• pp.30-40
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• 1998

Increasing water consumption produced sludge problems of the water treatment plants. The objective of this study is to investigate aluminium coagulants recovery n acidic and alkaline conditions. Water treatment plant sludge produced in Pusan Metropolitan City were tested for the aluminium extraction process. Experiment samples were obtained in summer from water treatment plants of Deoksan and Myongjang. Aluminium coagulants used in these plants during the test period were polyaluminium chloride(PAC), polyaluminium sulfate organic(PSO), polyaluminium sulfate silicate(PASS). Aluminium contents of water treatment sludge were in the range of 7.2~10.9% of the total solids. The recovery percentages for aluminium and iron by acidic extraction method was evaluated to 88% and 42% respectively. Extracted mass variation for other materials such as iron, manganese, total organic carbon was observed during the extraction operation. Alkaline extraction produced more than two times amount of total organic carbon than that in the acidic extraction process.

• 대한환경공학회지
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• 제22권12호
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• pp.2175-2185
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• 2000

호흡율은 활성미생물의 상태를 정확하게 나타낼 수 있는 상태변수로서 활성슬러지 공정을 모사하는데 유용하게 이용될 수 있다. 크게 competitive, noncompetitive, uncompetitive로 분류되는 독성물질은 미생물의 반속도상수와 비성장율을 증가/감소시켜 기질제거능을 떨어뜨린다. 본 연구에서는 장기폭기법으로 운전되는 pilot-scale 활성슬러지 공정을 대상으로 대표적인 noncompetitive 억제물질인 산성폐수가 유발하는 독성영향을 예측할 수 있는 모델을 도출하고 호흡율을 중심으로 활성슬러지의 거동을 모사하였다. Noncompetitive 억제 모델을 이용하여 pH 3.9~5.5의 산성폐수 유입시 호흡율의 실측치와 계산치는 상관계수가 0.96 이상으로 매우 근사한 결과를 보였다. 그러나 COD로 표현된 유출수 기질농도는 독성영향에도 불구하고 큰 변화를 보이지 않았다. 이는 유입수중의 생분해성 기질(readily biodegradable substrate) 농도가 낮기 때문인 것으로 판단되었다. 그리고 유입수의 기질농도 감소에 의한 호흡율의 감소보다 산성폐수에 의한 호흡율의 감소가 훨씬 크게 나타나 기질농도 감소에 따른 호흡율 기초 독성감지 장치의 오류 가능성은 적은 것으로 판단되었다.

• 대한환경공학회지
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• 제35권1호
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• pp.10-16
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• 2013

제당폐수를 산 또는 알카리 전 처리한 후 생물학적 수소생산율과 유기산의 생성특성을 평가하였다. 제당 폐수의 수소발생량은 산 전처리된 경우 보다 알칼리 전처리된 시료에서 약 70%의 발생량 증가를 나타내었다. 또한 제당폐수 원액에 적절한 영양염류(질소 인)를 공급하였을 때 보다 양호한 수소생성률을 보여주었다. 제당폐수의 혐기발효에 있어서 탄수화물의 분해와 수소생성의 직접적인 연관성은 나타나지 않았다. Butyric acid/Acetic acid (B/A)비와 수소생산의 연관성을 살펴보았을 때, 영양염류를 첨가한 제당폐수는 순수 제당폐수보다 B/A비가 약 3배 증가하였으며 알카리 전처리와 영양염류를 첨가한 시료에서 B/A비가 4.02로 가장 높게 나타났다. 실험에 사용된 전체 시료에서 B/A비가 클수록 수소생성률이 높았다.

• 분석과학
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• 제14권3호
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• pp.266-273
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• 2001

염소표백공정을 포함하고 있는 펄프 제지폐수 배출시설의 폐수 중 다이옥신류의 배출 특성 및 형성 메카니즘을 규명하기 위해 표백공정 전 후단에서 배출되는 산성 원폐수를 채취 분석하였다. 표백공정 전단 및 후단에서 배출되는 퓨란류(PCDFs)와 다이옥신류(PCDDs)는 약 2:3의 비율로 배출되었으며, 표백공정 전당에 비해 후단에서는 1,2,3,7,8 - 오염화다이옥신(PeCDD)을 제외한 2,3,7,8-치환이성체들의 배출농도가 증가된 것으로 조사되었다. 특히, 2,3,7,8-사염화퓨란(TCDF)은 0.0322ng/L에서 0.1580ng/L 약 5배, 팔염화다이옥신(OCDD)은 0.0794ng/L에서 0.5745ng/L로 7배 배출농도가 증가된 것으로 조사되었으며, 표백공정중 이들 이성체가 주로 형성 배출되어 전형적인 펄프 제지 제조시설의 다이옥신 배출패턴을 나타내고 있는 것으로 나타났다.

• 환경위생공학
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• 제15권3호
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• pp.62-69
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• 2000

In point of recycling wastes, batch test was conducted to examine the neutralization and Fe removal from laboratory wastewater using wastes. Oyster shell and slag had a buffer capacity to neutralize an acidic wastewater but tire rubber didn't. With increasing reaction time, dosage and agitation speed, Fe was well removed by wastes. As a result on the experiments of Freundlich isotherm, the adsorption intensities(1/n) were 0.32∼0.46 and the adsorption capacities(k) were 4.3∼4.6 for removing Fe from laboratory wastewater by wastes. In view of these results, it was estimated that wastes containing the similar compositions as these could utilize the neutralization and adsorption of heavy metals in laboratory wastewater.

• 상하수도학회지
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• 제21권1호
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• pp.123-130
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• 2007

The effects of hydrogen peroxide treatment on the reduction of waterworks sludge were investigated in this study. Sludge treated by peroxidation $H_2O_2$ oxidation) was dewatered using a pressure filter at 3atm. It was observed that $H_2O_2$ treatment at the acidic condition significantly reduce both cake water content and specific resistance to filtration (SRF), indicating the enhancement of dewaterability and filterability. The filterability by hydrogen peroxide treatment at pH 3.5 was better than acidic treatment and became comparable with polymer conditioning. The sludge filterability evaluated by SRF was optimal at a dose 2ml $H_2O_2$/sludge($0.02g\;H_2O_2/gTS$) after adjusting of pH to 3.5. The $H_2O_2$ oxidation at pH 3.5 also produced even more dewatered cake when compared with polymer conditioning. The reduction rate of sludge mass at an optimal condition showed 34% compared with untreated sludge. The effects of peroxidation on sludge properties including zeta potential, bound water and particle size were also evaluated. Peroxidation at the acidic condition reduced both bound water and zeta potential. By $H_2O_2$ combined with sulfuric acid leached iron caused Fenton's reaction, which showed a potential to significantly reduce the amount of solids mass and to produce more compact cake with higher filterability.

• 상하수도학회지
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• 제34권6호
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• pp.425-435
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• 2020

Numerous chemical modifications on activated carbon such as acidic conditioning, thermal treatment and metal impregnation have been investigated to enhance adsorption capacities of micropollutants in water treatment plants. In this study, chemical modification including acidic, alkaline treatment, and iron-impregnation was evaluated for adsorption of 2,4-dichlorophenol (2,4-DCP). For Fe-impregnation, three concentrations of ferric chloride solutions, i.e., 0.2 M, 0.4 M, and 0.8 M, were used and ion-exchange (MIX) of iron and subsequent thermal treatment (MTH) were also applied. Surface properties of the modified carbons were analyzed by active surface area, pore volume, three-dimensional images, and chemical characteristics. The acidic and alkaline treatment changed the pore structures but yielded little improvement of adsorption capacities. As Fe concentrations were increased during impregnation, the active adsorption areas were decreased and the compositional ratios of Fe were increased. Adsorption capacities of modified ACs were evaluated using Langmuir isotherm. The MIX modification was not efficient to enhance 2,4-DCP adsorption and the MES treatment showed increases in adsorption capacities of 2,4-DCP, compared to the original activated carbon. These results implied a possibility of chemical impregnation modification for improvement of adsorption of 2,4-DCP, if a proper modification procedure is sought.

• 한국물환경학회지
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• 제36권2호
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• pp.137-147
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• 2020

A direct contact membrane distillation (DCMD) was applied to treat strong nitrogenous wastewater of anaerobic digestion supernatant (ADS) and human urine (HU). The ammonia transfer was evaluated in terms of specific ammonia transfer (SAT) value, which is the ratio of total ammoniacal nitrogen divided by the amount of water transferred. The acidification resulted in low SAT values and high quality of produced water. The ammonia transfer control in the acidic condition was stronger for HU than ADS due to higher alkalinity (pH 8.8) and ammonia concentration (5700 mg-N/L) of HU. Acidified HU at pH 4 exhibited a SAT value of 1.64 × 10^-5, which was significantly smaller than the SAT value of 3.00 × 10^-3 for the original HU. The low pH enhanced the water flux for ADS, but HU showed a steep decrease in water flux due to enhanced fouling. It was considered that the fouling intensity in acidic conditions depends on the characteristics of the wastewater source. The major foulants on the MD membrane were NaCl, CaCO₃ and CuSO₄ as recognized by the SEM-EDS. Acidified ADS and HU at pH 4 showed relatively high N content of 8.18 % and 28.03 %, respectively, as organic fouling.