• 대한환경공학회지
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• 제30권8호
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• pp.775-780
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• 2008

슬러지 개량은 폐 슬러지의 응집성 및 탈수성을 개선하기 위해 슬러지 처리 공정에서 널리 사용되고 있다. 본 연구는 3종의 응집제(Alum, FeCl$_3$ 및 PAC)를 이용하여 응집제 주입량과 슬러지 케이크의 탈수성의 정량적인 상관관계를 도출하고자 하였다. Alum, FeCl$_3$ 및 PAC가 0.79$\sim$1.19 mmol/g, 0.61$\sim$1.25 mmol/g TSS, 및 0.21$\sim$0.39 mmol/g TSS로 주입되었을 때, 슬러지의 여과비저항은 초기값에 비해 약 95.0% 이상 감소되었다. 이 실험 결과에서 슬러지 g당 응집제 주입량(D)과 무차원 여과비저항(R)의 관계는 지수함수적인 관계로 나타낼 수 있었다.

• 펄프종이기술
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• 제32권3호
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• pp.1-9
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• 2000

The MDDA (Modified Dynamic Drainage Analyzer) was developed to evaluate the drainage characteristics on paper machine. The initial forming vacuum velocity was decreased with the increase of stock consistency and there were no significant effects of the applied vac-uum. On the other hand the initial forming drainage velocity was rapidly decreased with the increase of stock consistency above the 0.35 bar of applied vacuum. The final drainage time and wet web permeability showed similar trends under 0.075% consistency but increased rapidly at the higher consistencies. SFR(Specific Filtration Resistance) and drainage obtained for different vacuum level applied and deposited weights measured by using MDDA showed the linear relationship.

• 한국환경보건학회지
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• 제35권1호
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• pp.58-63
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• 2009

This study investigated improvement to sludge dewaterability and coagulation for sewage treatment plant sludge by using sodium hypochlorite solution (NaOCl), ferric sulfate [$Fe_2(SO_4)_3$] and zeolite. The specific resistance to filtration(SRF), chloride, pH and turbidity were used to evaluate the sludge dewatering behaviors. The results of study were as follows: By varying the amount of NaOCl added the optimum result in terms of enhancement for pretreatment occurred when 34 mg/l of NaOCl was injected. When the total solids concentration of the sludge was 10,000 mg/l, the optimum ferric sulfate dosage for the sludge dewaterability was 150 mg/l and the corresponding SRF was $1.7{\times}10^7sec^2/g$. It was observed that injecting zeolite into sludge was effective in improving the dewaterability of sludge.

• 미생물학회지
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• 제26권2호
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• pp.73-81
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• 1988

$\alpha$-Amylase (EC.3.2.1.1) of Neurospora crassa (ATCC9279) was cloned in E. coli HB101 using shotgun method, and the enzymes isolated from both N. crassa and E. coli were compared. Chromosomal DNA isolated from the spores of N. crassa was partially digested with PstI restriction endonuclease and rejoined to pBR322 which had been digested with the same enzyme. The resulting recombinant DNA were introduced into E. coli HB101 which had competancy by treating with $CaCl_{2}$. As the result, about 8000 colonies which showed tetracycline resistance were selected and two of the colonies which had 13.5Kb recombinant plasmid exhibit starch degrading activity on starch-containing plate when treated with D-cycloserine. $\alpha$-Amylases from both N.crassa and E. coli were isolated by using ammonium sulfate precipitation, DEAE-cellulose ion exchange column chromatography and Bio-Gel P150 gel foltration column. As the result, about 81.3 fold and 5.6 fold purifications in specific activities were obtained respectively, and specific activities of the gel filtrates were 6.1u/mg and 85u/mg respectively. The properties of both enzymes were compared and they showed quite the similar patterns in optimal temperature, optimal pH and had same molecular weight about 100,000 daltons on gel filtration method. Optimal temperatures for both enzymes were $70^{\circ}C$ and optimal pH were about 6 and 10.

• 멤브레인
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• 제11권1호
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• pp.14-21
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• 2001

막오염을 줄이기 위해 고빈도 역충격 시스템을 적용한 새로운 분리막 모듈을 연구하였다. 폴리아크릴로니트릴(Polyacrilonitrile) 재질의 외경 1.4mm, 내경 0.9mm, 분획분자량 50,000인 한외여과막과 라텍스(latex)용액을 사용하여 실험하였다. 역충격을 중공사막에 적용했을 때 제안된 모델식에 의한 이론치와 실험치를 비교 분석하였고, 역충격을 적용했을 때와 하지 않았을 때의 경우를 비교하였다. 이론치를 계산하기 위해 비저항 계수(specific cake resistance), 케익성장시간상수(time constant for cake growth), 확산계수(diffusion coefficient), 그리고 4가지 오염모델의 속도상수를 구하였다. 고빈도의 역충격을 가한 모듈의 투과율은 역충격이 없을 때의 투과율보다 약 40∼120%가 증가하였고 모델을 이용한 예상값과 1∼14% 내의 오차 범위를 나타냈다. 최적 역충격 세기는 20∼40%의 범위에서 20%였고 최적 역충격 빈도수는 0.67∼3Hz 범위에서 2Hz로 나타났다.

• 대한환경공학회지
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• 제22권7호
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• pp.1225-1232
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• 2000

연간 발생량이 1,563천톤에 달하는 하수슬러지의 효율적인 감량화 및 안정화를 위하여 전자선조사시의 물리 화학적 특성변화를 살펴보고 탈수에 미치는 영향에 대하여 고찰하였다. 슬러지에 3~20kGy의 전자선을 조사한 경우, pH와 알칼리도는 증가하는 양상을 띠었으며, 3kGy 조사시 용존단백질농도는 2.2배, SCOD는 10배 이상 증가하여 후속처리로 혐기성소화와 연계시 양질의 기질을 제공할 수 있어 전처리로서의 효과가 매우 우수함을 알 수 있었다. 여과비저항을 통해 살펴본 슬러지의 탈수성은 소화슬러지에 6kGy의 전자선을 조사한 경우 원슬러지에 비해 8.8배 가량 향상되었으며, 동일조건에서 화학개량한 경우에도 전자선을 조사한 슬러지의 탈수성이 4~10배 우수한 것으로 나타났다. 또한 여과비저항 측면에서만 볼 때 전자선조사만으로도 무기응집제를 통한 개량효과를 대치할 수 있는 것으로 조사되어 슬러지의 탈수성향상에 있어 전자선조사가 매우 효과적인 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.43-47
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• 2008

The nickel and cobalt resistance of Cupriavidus metallidurans CH34 is mediated by the CnrCBA efflux pump encoded by the cnrYHXCBAT metal resistance determinant. The products of the three genes cnrYXH transcriptionally regulate expression of cnr. CnrY and CnrX are membrane-bound proteins, probably functioning as anti-sigma factors, whereas CnrH is a cnr-specific extracytoplasmic functions (ECF) sigma factor. The periplasmic domain of CnrX (residues 29-148) was cloned as a N-terminal His-tagged protein, expressed in Escherichia coli, and purified using affinity chromatography and gel filtration. The molecular mass was estimated to be about 13.6kDa by size exclusion chromatography, corresponding to a monomer. The tetragonal bipyramid crystals were obtained by mixing an equal volume of protein in 50mM Tris-HCl, pH 7.5, 1% glycerol, 100mM NaCl, 1mM DTT, and the reservoir solution of 15% w/v PEG 2000, 100mM lithium chloride at 277K in 2-4 days using hanging drop vapor diffusion. The protein concentration was 24mg/ml. The crystal that diffracted to $2.42{\AA}$ resolution belongs to space group $P4_1\;or\;P4_3$ with unit cell parameters of $a=b=32.14{\AA},\;c=195.31{\AA},\;{\alpha}={\beta}={\gamma}=90^{\circ}$, with one molecule of CnrX in the asymmetric unit.

• 상하수도학회지
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• 제9권2호
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• pp.84-96
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• 1995

The dewatering characteristics of the sewage sludge was investigated through the experimental observations and model simulations. The activated sludge and the anaerobically digested sludge were examined for the dewaterability evaluation within the pressure range of $0{\sim}10^6N/m^2$. Modified Buchner funnel test and compression test by the consolidometer were conducted to evaluate average specific resistance, porosity, and moisture percentage of filter cake. Shirato's technique of compression-permeability test was followed for the pressure range lower than about $10^2N/m^2$. The flocculation effects on sludge dewatering was also examined for ferric chloride and polymeric flocculant. The application of hydrated lime which can be used for flue-gas desulfurization showed improved moisture percentage, and was thought to have positive feasibility in combined system of sludge dewatering and incineration. Determined characteristic constants were applied to Tiller's cake filtration model to simulate liquid pressure distribution and porosity distribution in cake. Model simulations showed a sharp drop of the porosity close to the cake-medium interface for the highly compressible material such as the activated sludge and the anaerobically digested sludge.

• 상하수도학회지
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• 제18권5호
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• pp.608-618
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• 2004

Since polyelectrolytes have been used as conditioners, conventionally only a single polyelectrolyte has been added for sludge conditioning. However, the amount of polyelectrolyte needed for optimal conditioning of sludge is very critical. Overdosing reduces the sludge dewaterbility. In this experimental study, sludge conditioning with single or dual polyelectrolyte was conducted to avoid problems associated with overdosing. Single polyelectrolyte conditioning was conducted by one of cationic, nonionic, and anionic polyelectrolytes. The dual polyelectrolyte conditioning was performed by adding one polyelectrolyte and another one in sequence. The dewaterbility of sludges were measured by SRF(specific resistance to filtration), TTF(time to filter), CST(capillary suction time) respectively. Additionally, parameters such as turbidity, zeta potential, viscosity of conditioned sludges or supematant were measured to evaluate the changed characteristics of sludge by addition of polyelectrolytes. From the experiment results, it was concluded that single polyelectrolyte conditioning had a high probability of overdosing, whereas dual polyelectrolyte conditioning resulted in a better dewaterbility and less chance of overdosing. But, it was also found that dosing sequence in dual conditioning was very important according to the characteristics of sludge. Parameters such as viscosity, turbidity, zeta potential were found to be useful as a means of evaluating sludge dewaterbility.

• 한국환경보건학회지
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• 제37권6호
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• pp.467-473
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• 2011

Objectives: Wastewater treatment plants typically produce a large volume of waste sludge. In this study, the conditioning and dewatering properties of a digested and thickened sludge from an industrial wastewater treatment plant were investigated in order to improve the dewaterbility of the sludge. Methods: Jar-tests and Buchner funnel tests were carried out to assess the conditioning and dewatering properties of a waste sludge. TTF (Time to Filter Test) and SRF (Specific Resistance to Filtration) were adopted as the indices of sludge dewaterbility. Results: The valuation indices influencing the dewaterbility of the waste sludge, including TTF, SRF, water contents, VS/TS ratio and turbidity, were measured. The TTF and SRF of the digested and thickened sludge were decreased to 40 sec, $3.43{\times}10^{12}$ m/kg, and 39 sec, $1.09{\times}10^{12}$ m/kg, respectively. Conclusions: The conditioner composed of natural inorganic materials turned out to be effective in the reduction of sludge water contents.