• Advances in environmental research
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• 제5권2호
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• pp.141-151
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• 2016

Large amounts of aluminum hydroxide ($Al(OH)_3$) exist in water purification sludge (WPS) because of the added aluminum coagulant in water treatment process. Notably, $Al(OH)_3$ is an amphoteric compound, can be dissolved in its basic condition using sodium hydroxide to form aluminate ions ($Al(OH)_4{^-}$). However, in a process in which pH is increasing, the humid acid can be dissolved easily from WPS and will inhibit the recovery and reuse of the dissolved aluminate ions. This study attempts to fix this problem by a novel approach to separate $Al(OH)_4{^-}$ ions using nanofiltration (NF) technology. Sludge impurity in a alkaline solution is retained by the NF membrane, such that the process recovers $Al(OH)_4{^-}$ ions, and significantly decreases the organic matter or heavy metal impurities in the permeate solution. The $Al(OH)_4{^-}$ ion is an alkaline substance. Experimental results confirm that a recovered coagulant of $Al(OH)_4{^-}$ ion can effectively remove kaolin particles from slightly acidic synthetic raw water.

• 한국염색가공학회지
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• 제9권6호
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• pp.26-32
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• 1997

In order to remove the pollutants effectively in the dye-processing wastewater by chemical precipitation, coagulation and flocculation test was carried out using several coagulants on various reaction conditions. It was found that the Ferric sulfate was best coagulant for the treatment of mixed dye-processing wastewater. When the Ferric sulfate dosage was 1,100mg/$\ell$, the COD removal rate was very high(50%), and the color was removed very effectively. The COD was decreased relatively well up to 40%, when Alum was dosed as coagulant. But it was difficult to remove the color effectively. Test results about COD removal for the Ferrous sulfate and the Ferric chloride used were mostly same as those of the Alum used. However, the color removal by the Ferrous sulfate was much better than the case of the Alum or the Ferric chloride. It was found that the COD removal was increased and the sludge yield was decreased by pH control before polymer flocculant addition, during the jar test for the Ferrous sulfate and the Ferric sulfate as a coagulant.

• 대한환경공학회지
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• 제35권12호
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• pp.883-888
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• 2013

조류 발생이 문제시 되는 정체수역이나 호소에서 현장적용에 적합한 응집제를 선정하고 응집제별 적정 주입농도를 찾기 위하여 황토와 개량된 토양기반 무기응집제 세 가지(AC-A, AC-B, AC-C)를 주입하며 응집 침전실험을 실시하였다. 남조류가 주종이고 조류밀도가 2,950 cells/mL인 원수에 대한 황토(50 mg/L 주입)에 의한 조류밀도 제거율은 10분 침전후 49%, 30분 침전후 85%로 나타났고, 다른 세 가지 무기응집제(20 mg/L 주입)의 경우 10분 침전 후 80-90% 제거율, 30분 침전 후에는 89-94%의 조류 제거율을 나타냈다. 조류 제거와 탁도, pH 등의 수질인자 특성을 종합적으로 고려할 때 본 연구에서 고려된 천연 무기응집제 중 AC-A가 가장 적합한 것으로 판단된다. 원수의 조류밀도가 높을수록 같은 제거효율을 얻기 위한 응집제 주입량이 증가하는 경향을 나타냈으나 선형적인 상관관계는 찾을 수 없었다. 황토를 비롯한 천연 무기응집제는 원수의 유기물 제거 및 pH 변화에는 큰 영향을 미치지 않는 것으로 나타났고, 인산염의 경우 주입량을 늘임에 따라 제거율이 높아져 최대 70%까지 제거되었다.

• 상하수도학회지
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• 제26권2호
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• pp.229-236
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• 2012

염기도를 달리하여 제조된 PACl에 대한 Al(III)종 분포는 염기도가 높을수록 monomeric Al(III)종은 적어지고, precipitate Al(III)종은 증가하는 것으로 나타났다. 염기도 13.6%의 경우에서는 monomeric Al(III)종이 81%, polymeric Al(III)종이 19%, precipitate Al(III)종은 0%로 monomeric Al(III)종이 주종을 이루고 있었다. 염기도 13.6%의 경우에서 재안정화 없이 80% 정도의 탁도제거 효율을 유지하고 있었으며, $UV_{254}$ 제거효율이 향상되는 것은 낮은 응집 pH 범위에서 유기물 응집효과가 우수하게 나타나기 때문으로 판단된다. 그리고 13.6% 염기도를 가진 PACl이 T-P 제거효율 및 $PO_{4}-P$의 제거효율이 가장 우수한 것으로 나타났으며 이는 높은 monomeric Al 성분에 기인하리라 판단된다.

• Korean Chemical Engineering Research
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• 제51권2호
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• pp.257-262
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• 2013

부영양화 방지를 위하여 규제되는 총인(Total-phosphorous, T-P) 농도가 0.2~2 mg/L 이하로 변경됨에 따라, 응집 처리 과정에서 인의 제거를 시도하게 되었다. 따라서 본 연구는 실제 하수종말처리장의 생물학적 처리수를 시료로 하여 티탄염 농도, pH 등의 인자가 인 제거에 미치는 특성에 대하여 검토하였다. 또한 실제 현장에서 가장 많이 사용되는 침강식 침전조와 가압부상식 침전조에 티탄염을 적용하여 인 제거 효율 및 슬러지 활용 가능성을 조사하였다. 응집제로 티탄염을 사용하는 경우 인 제거효율이 기존에 사용하는 황산 알루미늄($Al_2(SO_4)_3$, Alum)과 유사하였다. 하향 침강방식의 침전조와 가압부상방식의 침전조 모두 기준치 이하로 모두 현장 적용이 가능하였다. 생성된 산화티탄의 성분은 원수에 포함된 무기물과 투입된 티탄염 성분으로 구성되었다. 티탄염 응집 후 생성된 슬러지를 소성하여 산화티탄을 제조하였다. 시판되고 있는 P-25 제품과 유사한 광촉매 활성을 가지고 있어 슬러지에서 생성된 산화티탄도 기존에 사용하는 제품시장에 대체 사용이 가능할 것으로 판단된다.

• 한국염색가공학회지
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• 제12권2호
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• pp.96-102
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• 2000

For the effective treatment of dyeing-complex wastewater, the most effective chemical coagulation method was studied. For the chemical coagulation of dyeing-complex wastewater, polyferric sulfate, $4Al_2(SO_4)_3$, PAC, ferrous sulfate, ferric sulfate, $FeCl_2$ and lime were used. It was investigated that polyferric sulfate was the most efficient coagulant. The optimal conditions and results for polyferric sulfate include the followings. When initial $COD_{Mn}$ concentration was 600mg/L, the optimal initial pH, dosage of coagulant, dosage of lime and PAA for $COD_{Mn}$ removal efficiency were 5, 1,200mg/L, 500mg/L and lmg/L, respectively. The optimal dosage of polyferric sulfate was increased proportionally to the influent $COD_{Mn}$ concentration.

• 환경위생공학
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• 제17권3호
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• pp.89-98
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• 2002

The changes of conventional clarification process and an increase in treatment cost are required to meet increasingly stringent regulations related to the treated water quality. Although many enhanced coagulations have introduced to improve organic matter removal, the results to remove color, nitrogen and phosphorus as well as organic material have not been very efficient yet. The removal of waste matters such as SS, organic matter, color and turbidity contained in dyeing wastewater was carried out by using the combination of calcium hydroxide and magnesium sulfate. The flocculation was investigated as a function of coagulant dose, pH, mixing time, settling time and coagulant addition modes such as the sequential addition of the two coagulants and the simultaneous addition of them. The flocculation by the combination of calcium hydroxide and magnesium sulfate was compared with that by aluminum sulfate. The mechanism of flocculation was investigated as well. About 84% of color in dyeing watewater was removed by flocculation with combination of calcium hydroxide and magnesium sulfate.

• 환경위생공학
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• 제17권4호
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• pp.10-18
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• 2002

The changes of conventional clarification processe and an increase in treatment cost are required to meet increasingly stringent regulations related to the treated water quality. Although many enhanced coagulations have introduced to improve organic matter removal, the results to remove color, nitrogen and phosphorus as well as organic material have not been very efficient yet. In this context as new flocculation using calcium hydroxide and magnesum sulfate was carried out. The removal of waste matters such as SS, organic matter, COD, nitrogen and phosphorus contained in stock wastewater was carried out by using the combination of calcium hydroxide and magnesium sulfate. The flocculation was investigated as a function of coagulant dose, pH, mixing time, settling time and coagulant addition modes such as the sequential addition of the two coagulants and the simultaneous addition of them. The flocculation by the combination of calcium hydroxide and magnesium sulfate was compared with that by aluminum sulfate. The mechanism of flocculation was investigated as well. About 60% of COD in stock watewater was removed by flocculation with combination of calcium hydroxide and magnesium sulfate.

• 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.

• 한국환경보건학회지
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• 제19권2호
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• pp.1-9
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• 1993

In public water supply systems, Alum and/or PAC being used as a coagulant. It is well known that their use increased frequently the concentration of residual aluminum in filtered water upon operating conditions. This study was conducted to find the optimum conditions that both the concentration of residual aluminum and turbidity are minimized by changing such factors as pH, temperature, alum dosage, mixing rate, alkalinity and hardness. The results can be summarized as follows: The pH values for the minimum concentration of residual aluminum and turbidity as a given experimental condition were found at pH 6 and pH 7 respectively, the apparent clarity was best at pH 8. The floc settling rate was the greatest at pH 6.5, but the turbidity was high at the same condition. The more alum dosage, the higher the concentration of residual aluminum. However the alum dosage less than 15 mg/l tend to decrease in turbidity. Restabilization and enmeshment occurred near 15 mg/l and 20 mg/l of alum dose respectively. With the increase of mixing rate (rapid and slow), the concentration of residual aluminum and turbidity are increased and the same trend was found in increment of mixing time. At low water temperature, the concentration of residual aluminum was decreased, but turbidity was increased. It was confirmed that alkalinity had an effect on the coagulation efficiency, but hardness did not.