• 환경위생공학
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• 제10권2호
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• pp.30-35
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• 1995

In this research effect of physicochemical parameter on flocculation using PASS-100 were evaluated. pEt flocculant dosage, mixing intensity and detention time were adopted as experimental variables. The physicochemical parameter( p% mixing intensity and mixing time ) were important Parameter on flocculation performance. Effluent pH range for effective flocculation was 4.5-7. Optimum Gt$_{d}$ range was 20,000-30,000 and its range similar to alum flucculation. Rapid mixing was very important parameter to floe formation in PASS- 100 flocculation. Whereas, slow mixing did not affect to the removal efficiency at settling time for 30minute or more.

• Journal of Microbiology and Biotechnology
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• 제16권12호
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• pp.1874-1881
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• 2006

Flocculation of Candida tropicalis HY200 was systemically investigated to elucidate its mechanism, and used for cell cycles in repeated-batch cultivations for the production of xylitol from xylose. Flocculation occurred only after the late exponential phase of growth in the culture media and buffer within the narrow pH range of 3.0-5.0. The flocculation was completely inhibited by treatments of cells with proteases and partially reduced by treatments with carbohydrate-hydrolyzing enzymes and by the presence of mannose and glucose. The addition of calcium ions significantly enhanced the flocculation during cultivation, which was completely abolished by the addition of EDTA. The flocculent yeast HY200 provided repeated-batch cultivations employing cell recycles by flocculation over 6 rounds of cultivation for the production of xylitol from xylose, resulting in a relatively high productivity of averaged 4.6 g xylitol/l h over six batches and maximal 6.3 g xylitol/l h in the final sixth batch. Cell recycle by flocculation was fast and convenient, which could be applicable for the industrial scale of xylitol production.

• 한국미생물·생명공학회지
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• 제23권6호
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• pp.763-769
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• 1995

As a mean to recover photosynthetic bacterial(PSB) cells and its practical uses in food industrial wastewater treatment, various biodegradable polyelectrolytes were first investigated for flocculation of suspended colloids in the PSB treatment process of soybean curd wastewater. Anionic polyelectrolytes such as sodium alginate and carrageenan were not effective but a cationic polyelectrolyte chitosan isolated from Portunus trituberclatus showed very effective flocculation activity. The concentration of chitosan, pH and temperature of wastewater for maximal flocculation were 40 mg/l, pH 7 and room temperature, respectively. Test using deacetylated chitosan to various degree showed higher flocculating activities in samples deacetylated over 75% and time for maximum flocculation was 40 min by stirring slowly under the above optimal conditions. Chitosan was not only effective to flocculate cells but also removed COD and MLSS of the wastewater. COD of 42% and MLSS of 87% were removed by addition of chitosan to the soybean curd wastewater treated with PSB.

• KSBB Journal
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• 제29권3호
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• pp.220-224
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• 2014

Flocculation is known one of the effective methods for harvesting microalgae. This study was aimed to optimize the flocculation condition for decreasing the amounts of flocculant and obtaining the highest yield of algal biomass. To achieve this goal, it was optimized the flocculant concentration, reaction pH and the concentration of cell density for harvest using response surface methodology (RSM). The flocculation of microalgae, Spirogyra varians, was carried out using inorganic flocculant polyaluminium chloride. By the RSM result, the optimal flocculation condition was calculated 5 ppm of polyaluminum chloride, pH 7.5 and 0.33 of optical cell density at $OD_{640}$. The obtained recovery yield of S. varians was 97.6% at the optimal condition.

• 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.

• 펄프종이기술
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• 제40권4호
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• pp.10-15
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• 2008

Flocculation phenomena of the stock mixed with cellulosic fibers, fillers and polymers were investigated by a new turbidity measurement system consisted of a probe-type turbidimeter, data acquisition system and computer. The probe-type turbidimeter allowed to measure the real time flocculation of the stock induced by single polymer and microparticle systems. Flocculation phenomena were evaluated by average and final relative turbidity indices. Turbidity and flocculation showed inverse relationship, i.e. the turbidity decreased with the formation of flocs. Relative turbidity of the stock treated with microparticle system was lower than that of the stock containing single polymer system, which indicated that the microparticle system showed greater floc forming efficiency than single polymer system.

• 상하수도학회지
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• 제20권2호
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• pp.245-255
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• 2006

Dissolved air flotation is a solid-liquid separation system that uses fine bubbles rising from bottom to remove particles in water. In order to enhance the flotation velocity and removal efficiency of flocs in the flotation process, we tried to obtain pretreatment conditions for the optimum DAF process operation by comparing and evaluating features of actual floc formation and flotation velocity etc, according to coagulant types and conditions for flocculation mixing intensity by using PIA, PDA, and FSA. Accordingly, generating big flocs that have low density at low flocculation mixing intensity may reduce treatment efficiency. In addition, generating small flocs at high flocculation mixing intensity makes floc-bubbles smaller, which reduces flotation velocity, In this study, it was found that high flocculation mixing intensity could not remove the remaining micro-particles after flocculation, which had negative effects on treated water quality, Therefore, in order to enhance treatment efficiency in a flotation process, flocculation mixing intensity around $50sec^{-1}$ is effective.

• 대한환경공학회지
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• 제30권8호
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• pp.839-846
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• 2008

탈수된 케이크의 함수율을 저감하기 위하여 폴리아크릴아마이드계 고분자 응집제의 응집특성을 평가하였다. 하수 슬러지의 탈수효율은 응집제의 종류, 교반 속도 및 시간, 용해수의 농도 등에 관계된 두드러진 영향이 있음을 알게 되었다. 최적 교반 속도 및 시간은 실험조건에서 각각 700 rpm 및 3초이었다. 탈수효율은 700 rpm까지는 비례적으로 증가하였다. 응집제의 용해수로 재이용수를 사용하였을 때, 모든 종류의 용해점도는 감소되었다. 그러나 그 점도 변화는 각 응집제의 탈수효율과 비례하지는 않았다. 1차 및 2차 응집반응의 조합으로 한가지 응집제를 사용한 응집 시스템을 평가하였다. 2단 응집공정의 1차 및 2차 투입량 비율의 탈수효율에 대한 영향 또한 평가하였다. 2단 응집 시스템의 최적 조건은 저 및 고점도 응집제에 각각에 대하여 총투입량 대비 1차 투입량이 75%와 50%이었다. 그 결과를 기초로, 2단 응집의 전체 메커니즘을 제안하였으며, 이러한 방법으로 응집 공정들을 최적화함으로써 비용 절감이 가능함을 예상할 수 있었다.

• 한국환경기술학회지
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• 제19권6호
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• pp.563-569
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• 2018

본 연구에서는 영양염류 및 응집을 중심으로 미세조류를 이용한 폐수처리 효율에 관한 연구를 수행하였다. 미세조류 배양을 통한 폐수의 영양염류 저감의 가능성을 확인하기 위하여 미세조류의 배양에 따른 인 및 질소의 제거율을 관찰한 결과, 각각 약 92 % 및 99 % 이상의 제거율을 보였다. 효율적인 미세조류의 회수를 위하여 Auto-flocculation 조건 및 다양한 첨가물에 따른 응집실험을 진행한 결과, 응집제인 PAC(Poly Aluminum Chloride) 및 $FeCl_3$를 첨가한 경우에 각각 평균 94 % 및 92 %의 높은 응집율을 보였다. 또한, 최소한의 농도로 90 % 이상의 응집율을 보이는 최적의 조건을 찾기 위하여 응집제별 최적농도 산출 실험을 진행하였으며, 그 결과 PAC는 30 mg/L, $FeCl_3$는 40 mg/L가 최적의 농도임을 확인하였다.

• 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.