• 펄프종이기술
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• 제41권2호
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• pp.13-19
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• 2009

In order to produce high quality paper at the lowest cost in high speed, typically various polyelectrolytes as retention aids were used. Retention systems such as single polymer system, dual polymer system, and microparticle system were used. The objective of this study was to analyze the changes of retention, drainage, formation and fracture toughness depending on types of retention system, molecular weight of C-PAM and dosage sequences of agents. When single polymer system was applied, retention was increased with poor formation and drainage. When common microparticle system(C-PAM/bentonite) was used, high molecular weight PAM gave high retention and fast drainage, but poor formation. When the microparticle system with reverse dosage sequence(bentonite/C-PAM) was used, low molecular weight PAM gave high retention, fast drainage and good formation. When various retention agents were applied, fracture toughness was increased than that of blank. When using high molecular weight PAM and consequently causing excessive flocculation, fracture toughness was decreased.

• Membrane and Water Treatment
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• 제2권3호
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• pp.175-185
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• 2011

Ultrafiltration is an emerging technology for drinking water treatment because it produces better water quality as compared with conventional treatment systems. More recently, the combination of UF technology with other processes in order to improve its performance has been observed. These associations aim to maximize the contaminants removal and reduce membrane fouling. The operational performance of contaminants removal and water production of two UF pilot plants was compared. The first plant (Guarapiranga) was fed with raw water and the second plant (ABV) with pre-treated water by the coagulation, flocculation and sedimentation processes at Alto da Boa Vista WTP (Sao Paulo, Brazil). Both units operated continuously for approximately 2,500 hours, from September/2009 to January/2010. The results showed that the ABV UF pilot plant was able to operate at higher specific fluxes (6.2 $L.d^{-1}.m^{-2}.kPa^{-1}$ @ $25^{\circ}C$) than Guarapiranga (3.1 $L.d^{-1}.m^{-2}.kPa^{-1}$ @ $25^{\circ}C$). However, the number of chemical cleanings conducted in both pilot units during the considered operation period was the same (4 chemical cleanings for each plant), which shows that the pre-treatment reduced the membrane fouling. The water quality at ABV for all the variables analyzed was better, but the feed water quality was also better due to pretreatment. The rejection values for the different contaminants were higher at Guarapiranga mainly because of a pollution load reduction after pre-treatment at ABV. Even with the better performance of the ABV UF pilot plant, it is necessary to take into consideration the complexity of the complete treatment system, and also the costs involved in the construction and operation of a full-scale treatment unit.

• Advances in environmental research
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• 제2권3호
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• pp.229-243
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• 2013

Coagulation-flocculation (CF) was tested coupled with an aerobic biofilter to reduce total petroleum hydrocarbon (TPHs) concentration and toxicity from petrochemical wastewater. The efficiency of the process was followed using turbidity and chemical oxygen demand (COD). The biofilter was packed with a basaltic waste (tezontle) and inoculated with a bacterial consortium. Toxicity test were carried out using Lactuca sativa var. capitata seeds. Best results for turbidity removal were obtained using alum. Considerable turbidity removal was obtained when using Opuntia spp. COD removal with alum was 25%, for Opuntia powder it was 36%. The application of the biofilter allowed the removal of 70% of the remaining TPHs after 30 days with a biodegradation rate (BDR) value 47 $mgL^{-1}d^{-1}$. COD removal was slightly higher with BDR value 63 $mgL^{-1}d^{-1}$. TPH kinetics allowed a degradation rate constant equal to $4.05{\times}10^{-2}d^{-1}$. COD removal showed similar trend with $k=4.23{\times}10^{-2}d^{-1}$. Toxicity reduction was also successfully achieved by the combined treatment process.

• 멤브레인
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• 제23권6호
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• pp.460-468
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• 2013

가압식 MF공정의 전처리공정으로 침전지가 없는 혼화/응집공정에서 적정응집제 투입농도선정 및 유기물 제거성능을 평가하였다. 전처리 공정에서 생성된 플럭이 가압펌프의 임펠러에 의해 해체됨을 확인하였으며 원수탁도가 10 NTU 이하로 유입이 될 때, 혼화/응집조와 펌프후단에서 플럭형성을 위한 최적응집제 투입량은 4 mg/L (as PACl 17%)이었다. 이때의 DOC 제거율은 평균 43%이었으며, 응집제투입량을 계속적으로 증가시켜 8 mg/L (as PACl 17%)로 투입을 하였을 때, DOC 제거율은 평균 48%를 나타내어 제거율은 크게 개선되지 않았다. 전처리가 없는 PVDF 가압식 MF공정의 TMP는 0.54 bar에서 운영이 되었으며, 혼화/응집 전처리 공정을 적용하여 운영 시 TMP는 0.41 bar로 안정적인 운영이 가능하였다.

• Current Research on Agriculture and Life Sciences
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• 제11권
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• pp.1-9
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• 1993

신문 용지용(用) 지료(紙料)의 조성조건(調成條件)에 따른 보류(保留)의 변화를 연구(硏究)한 결과 다음과 같은 사실을 알수가 있었다. 1. 온도(溫度)의 상승(上昇)에 따라 보류(保留)는 지료(紙料)의 종류 및 배합비(配合比)에 관계없이 감소(減少)하였으며 GP보다 DIP가 온도(溫度)변화에 민감(敏感)하였다. 2. pH변화에 따른 보류(保留)의 변화는 GP와 DIP 및 GP/DIP=50/50 모두 pH5에서 보류(保留)가 가장 높았으며 pH 5보다 높거나 낮으면 감소(減少)하였고 DIP가 GP보다 감소(減少)가 적었다. 3. Alum첨가(添加)에 따른 보류(保留)의 변화는 GP와 GP/DIP=50/50의 경우 2% 첨가(添加)에서 보류(保留)가 가장 높았고 DIP는 3% 첨가(添加)에서 가장 높았다. 4. 보류(保留)는 지료(紙料)의 응집작용(凝集作用)과 밀접한 관련이 있었다.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2747-2752
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• 2013

Surface modification of colloidal silica nanoparticles without disrupting the electric double layer of nanoparticles is a major challenge. In the work, silane was employed to modify colloidal silica nanoparticles without inducing bridge flocculation obviously. The effect of pH value of the silica sol, the amount of silane in feed, and reaction temperature on the graft amount and the final size of modified particles was investigated. The increased weight loss by TG and the appearance of $T_2$ and $T_3$ except for $Q_2$ and $Q_3$ signals by CP/MAS $^{29}Si$ NMR of the modified samples verified the successful grafting of silane. The graft amount reached 0.57 mmol/g, which was slightly lower than theory value, and the particle size remained nearly the same as unmodified particles for acidic silica sol at the optimum condition. For alkaline silica sol after modification, aggregates composed of several nanoparticles connected together with silane moleculars as the bridge appeared.

• 한국물환경학회지
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• 제34권1호
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• pp.121-131
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• 2018

Domestic sewage treatment plants (STPs) consume about 0.5 % of total electric energy produced annually, which is equivalent to 207.7 billion Korean won per year. To minimize the energy consumption and as a way of mitigating the depletion of energy sources, the sewage treatment strategy should be improved to the level of "energy positive". The core processes for the energy positive sewage treatment include A-stage for energy recovery and B-stage for energy-efficient nitrogen removal. The integrated process is known as the A/B-process. In A-stage, chemically enhanced primary treatment (CEPT) or high rate activated sludge (HRAS) processes can be utilized by modifying the primary settling in the first stage of sewage treatment. CEPT utilizes chemical coagulation and flocculation, while HRAS applies returned activated sludge for the efficient recovery of organic contents. The two processes showed organic recovery efficiencies ranging from 60 to 70 %. At a given recovery efficiency of 80 %, 17.3 % of energy potential ($1,398kJ/m^3$) is recovered through the anaerobic digestion and combustion of methane. Besides, anaerobic membrane bioreactor (AnMBR) can recover 85% of organic contents and generate $1,580kJ/m^3$ from the sewage. The recovered energy is equal to the amount of energy consumption by sewage treatment equipped with anaerobic ammonium oxidation (ANAMMOX)-based B-stage, $810{\sim}1,620kJ/m^3$. Therefore, it is possible to upgrade STPs as efficient as energy neutral. However, additional novel technologies, such as, fuel cell and co-digestion, should be applied to achieve "energy positive" sewage treatment.

• 한국지반환경공학회 논문집
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• 제8권3호
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• pp.5-10
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• 2007

본 연구는 도시하수와 응집, 오존처리, UV와 같은 물리화학적 방법으로 처리된 하수 속에 함유되어 있는 비 규제 유기오염물의 GC/MS를 통한 정성적 분석결과를 나타내었다. 하수 속에 함유된 주요 유기오염물질로는 식품 또는 가정, 공업적 사용으로부터 배출된 물질이 주류를 이루었다. 하수처리장의 생물학적 공정으로부터 몇몇 유기오염물질들의 처리효율은 효과적이었지만 일부의 유기오염물질의 제거는 그리 효과적이지 못하였다. 그러므로 생물학적 방법으로 처리가 효과적이지 못한 물질들의 처리를 위한 고도처리방법의 적용과 가정에서의 이러한 물질이 함유된 제품의 사용에 좀 더 적극적인 조절이 필요 할 것이다. 본 연구에서 얻은 결과는 하천유역에서 이들 오염물질의 특성 및 생태계에 대한 오염물질의 배출 평가에 기여를 할 수 있을 것이다.

• 펄프종이기술
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• 제46권1호
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• pp.39-45
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• 2014

Various approaches have been tried to reduce the emission of carbon dioxide in paper industry. One of important approaches is to use PCC manufactured from emission gas as a filler. However, it was recognized that PCC is inferior to other fillers in the paper strength properties of view. Therefore, pretreatment of PCC with pulp powder was tried to mitigate the strength reduction of paper. Pretreatment of PCC with pulp powder improved the bulk(7.4~12.9%) and air permeability(24.8~42.98%), but there is no significant change in opacity. Tensile index, burst index and stiffness were decreased by the use of pretreated PCC with pulp powder. Anionic and cationic PAM were used as a additive for PCC pretreatment in order to improve strength properties. There was no significant change in bulk in all kinds of PAM used in this study. Most strength properties were improved by the pretreatment of PCC with the anionic and cationic PAM and pulp powder, although the opacity and stiffness were more or less decreased.

• 한국환경보건학회지
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• 제35권5호
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• pp.411-416
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• 2009

This study was initiated to improve the cooling water quality by chemical coagulation and sedimentation in steel mills. Due to the inefficient flocculation in the settling tanks of blast furnace cooling water systems, the solid particles in the cooling water overflow accumulate and clog the cooling system. To protect the cooling water system from such fouling, proper flocculants must be continuously used. Laboratory tests were performed for the indirect cooling water system of a plate mill. The batch test in the gas scrubbing cooling water system of a blast furnace showed that the proposed coagulant was more effective for the improvement of coagulation and sedimentation than the existing one. During the tests, cationic flocculants were more effective than use of only an anionic flocculant. The suggested combination of anionic and cationic flocculants can probably improve the turbidity removal efficiency of the cooling water. Proper control of the overflow rate by the designed residence time would help turbidity removal efficiency in the settling tank. In addition, the settling can be enhanced by adopting rapid and slow mixing alternatively. Scale problems in blast furnace cooling water system were reduced to some extent by efficient settling.