• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.2
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• pp.101-109
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• 2004

In this study, the solid-liquid separation characteristics of swine wastewater were investigated for the coagulation and dissolved air flotation (DAF). Coagulation characteristics were studied using jar-tester with the different coagulants and dosage amounts. DAF characteristics were also investigated in terms of the different flotation conditions with the raw swine wastewater, pH adjustment only, and adding coagulants. When the raw swine wastewater was coagulated with the only inorganic coagulants, the proper inorganic coagulants were founded as $FeCl_3$ > PAC > Alum orderly, and the optimal coagulant dosages were founded as $1,000mg/{\ell}$, $1,500mg/{\ell}$, $1,500mg/{\ell}$, respectively. As the raw swine wastewater was treated with the polymer coagulants, the only cationic polymer coagulant showed an effective coagulation and the optimal dosage of cationic coagulant was founded as $200mg/{\ell}$. When the different dosages of cationic polymer was added to each $500mg/{\ell}$ of the inorganic coagulants, the proper inorganic coagulants were founded as $FeCl_3$ > Alum > PAC orderly, and optimal cationic polymer dosages was founded as $25mg/{\ell}$, $25mg/{\ell}$, and $100mg/{\ell}$, respectively. Resulting from the raw swine wastewater experiments using DAF without coagulation, the proper operation conditions of DAF were set to 400% of recycling ratio, 4 atm in air dissolving tank, and under pH 3. But the raw swine wastewater was difficult to successfully operate DAF without pre-coagulation. While the DAF separation after pre-coagulation using inorganic coagulants was not accomplished due to the low intensity of the floc, DAF after pre-coagulation using both the inorganic and cationic polymer coagulants was accomplished very well. Optimal dosage of cationic polymer coagulant in case of $500mg/{\ell}$ Alum dosage was founded as $500mg/{\ell}$.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.2
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• pp.125-139
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• 2017

In this paper, the performance of a synthetic fiber filter aimed at high-speed operation and dosed with different coagulants or filter aids was investigated. Without a coagulant, the filter efficiency was about 62% which was greatly enhanced when three types of coagulants namely PAC, Alum, and $FeCl_3$ were used. Among the coagulants tested, PAC was the most effective, giving 91% filter efficiency, followed by Alum with 90%, and $FeCl_3$ with 78%. PAC worked effectively at a very small range of dose, but Alum was relatively effective in a wide range of concentration. Compared with PAC and Alum, $FeCl_3$ provided more or less contant efficiency regardless of its dose but gave the poorest filter efficiency. Moreover, as the inflow turbidity increased, headloss increased and the efficiency decreased at any dose and type of coagulant. The headloss recorded in this particular synthetic fiber filter is not significant as compared to that observed in typical granular filters. The recovery of solids estimated after filter cleaning was about 80% for both PAC and Alum, but poorer at 72% in the case of $FeCl_3$ due to the heavy and large floc characteristics. The recurrence of filter efficiency verified through repetitive filter runs was found to be satisfactory.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.11
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• pp.834-846
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• 2011

The objective of this study is to development of IDFIS system, that are consisted of hydrocyclone, rapid flocculation and inclined settler with chitosan coagulant. As the results of Jar test, a chitosan optimum dosage of 40 mg/L for river sediment, and 5 mg/L for tunnelling wastewater sediment, which these conditions leaves of residual turbidity of less than 5 NTU. Because of the effectiveness of chitosan in removing turbidity was independent on pH, the operation of IDFIS system would be simple. The synthesized turbidity was made with clay particles, river sediment, river suspended sediment, and tunnelling wastewater sediment. Results indicate that the mean overall removal efficiency of turbidity, SS, COD and TP were 98%, 99%, 85% and 95%, respectively. Chitosan is very efficient in removing turbidity in the entire turbidity range examined. IDFIS system would have possibility with compact design, because of the increase of floc size favours the floc settling speed and reduces the settling time.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.629-635
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• 2012

This study was conducted to evaluate the removal behaviors of DOM(dissolved organic matter) and phosphorus in eutrophic lake water by coagulation process with PAC(powdered activated carbon). It was observed that the removal characteristic of soluble matter was different from that of dissolved one, and the removal of DOM was effected by both pH and coagulant dosage. It was founded that PAC could increase the removal efficiency by an adsorption of DOM in coagulation process. A formation of soluble and colloidal matters resulted in the degradation of phosphorus removal efficiency in a chemical precipitation process. The phosphorus removal efficiency could be enhanced by an absorption of colloidal matter and dissolved complex with PAC addition. In addition, the PAC addition caused the increase of floc density in coagulation process, that led to the rise of sedimentation rate, and resulted in a significant improvement of solid-liquid separation efficiency.

• Journal of the Korean Chemical Society
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• v.48 no.3
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• pp.273-282
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• 2004

The synthetic technology of improved polyaluminiumchloride (IPAC) similar to characteristics of PACS was established with minimum expense for modifying existing production line. The conditions for activating silicate was studied before the synthesis of IPAC, and the IPAC was synthesised with raw materials such as aluminumhydroxide and concentrated hydrochloric acid, followed by adding activated silicate and alginate. The specification of product, chemical structure, and coagulating properties were tested by using specification testing method, instrumental analytical method, and Jar tester, respectively. As a result, the product, IPAC, contained aluminium oxide content more than 17%, and no precipitation was shown at all while the IPAC solution was preserved, and the larger floc and faster coagulation were represented compared to existing PAC under the same conditions. It was suggested that these synthetic technology could be applied to the existing production line for producing PAC without approximately cost raising factor because of adding sulfuric acid-activated silicate instead of sodium sulfate.

• Journal of Environmental Health Sciences
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• v.19 no.2
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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.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.208-214
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• 2004

Dissolved air flotation (DAF) is an effective solid/liquid separation process for low density floc particles such as algal, color-alum and clay-alum flocs produced from low turbidity water. The removal of taste and odor-causing organics (2-mthylisoboneol and geosmin) originating from algae in drinking water is a local and worldwide concern. Although DAF has been effectively applied for the removal of suspended solid, its application for the treatment of dissolved organic carbon is very limited. In this study, a new hybrid system consisting of adsorption and DAF processes was introduced for the simultaneous removal of algae and taste and odor-causing organics. Powdered activated carbon (PAC) was used as an adsorbent. In this proposed system, the major concern of eliminating the spent PAC from the system was also addressed. It was found that zeta potential of algae and PAC was increased with coagulant dosage, and the removal efficiency in DAF was also enhanced up to 90~95% under the given experimental conditions. Based on this study, the hybrid process was found to be a promising technology for the simultaneous removal of algae and dissolved organic pollutants.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.581-589
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• 2005

Recently, membrane processes have been replacing the conventional processes for waste water treatment to produce better quality of effluent and to meet more stringent regulations because of water shortage. However, using membrane processes for water treatment has confronted with fouling and difficulty in treating dissolved organic pollutants. In this study, membrane process equipped with crossflow microfiltration is combined with coagulation process using alum and PAC to improve permeability and treatment efficiency. The effects of coagulant dosage and optimum membrane operating conditions were investigated from measurement of permeate flow, cumulative volume, total resistance, particle size, dissolved organic pollutant, dissolved aluminium and quality of effluent. Characteristic of PAC coagulation was compared with that of alum coagulation. PAC coagulation reduced membrane fouling because of forming larger particle size and increased permeate velocity and cumulative volume. Less dissolved organic pollutants and dissolved aluminum made decreasing-rate of permeate velocity being lowered. At using $0.2\;{\mu}m$ membrane, cake filtration observed. At using $0.45\;{\mu}m$ membrane, there was floc breakage due to shear stress occurred born circulating operation. It made floc size smaller than membrane pore size, which subsequently to decrease permeate velocity and to increase total resistance. The optimum coagulation dosage was $300{\pm}50\;mg/L$ for both alum and PAC. PAC coagulation was more efficiently used with $0.2\;{\mu}m$ membrane, and the highest permeate flux was in using $0.45\;{\mu}m$membrane. The greatest efficiency of treatment was as follows; turbidity 99.8%, SS 99.9%, $BOD_5$ 94.4%, $COD_{Cr}$ 95.4%, T-N 54.3%, T-P 99.8%.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.2
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• pp.243-252
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• 2007

Effects of alum dosage on the particle growth were investigated by monitoring particle counts in a rapid mixing process. Kaolin was used for turbid water sample and several other chemicals were added to adjust pH and ionic strength. The range of velocity gradient and mixing time applied for rapid mixing were $200{\sim}300sec^{-1}$ and 30~180 sec, respectively. Particle distribution in the synthetic water sample was close to the natural water where their turbidity was same. The number of particles in the range of $10.0{\sim}12.0{\mu}m$ increased rapidly with rapid mixing time at alum dose of 20mg/L, however, the number of $8.0{\sim}9.0{\mu}m$ particles increased at alum dose of 50mg/L. The number of $14.0{\sim}25.0{\mu}m$ particles at alum dose of 20mg/L was 10 times higher than them at alum dose of 50mg/L. Dominant particle growth was monitored at the lower alum dose than the optimum dose from a jar test at an extended rapid mixing time(about 120 sec). The number of $8.0{\sim}14.0{\mu}m$ particles was lower both at a higher alum doses and higher G values. At G value of $200sec^{-1}$ and at alum dose of 10-20mg/L, residual turbidity was lower as the mixing time increased. But at alum dose above 40mg/L and at same G value, lower residual turbidity occurred in a short rapid mixing time. Low residual turbidity at G value of $300sec^{-1}$ occurred both at lower alum doses and at shorter mixing time comparing to the results at G value of $200sec^{-1}$.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.2
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• pp.77-87
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• 2018

In this study, the effects of operating conditions on the formation of reversible and irreversible fouling were investigated in the filtration using ceramic membrane for water treatment process. The effect of coagulation pretreatment on fouling formation was also evaluated by comparing the performance of membrane filtration both with and without addition of coagulant. A resistance-in-series-model was applied for the analysis of membrane fouling. Total resistance (RT) and internal fouling resistance (Rf) increased in the membrane filtration process without coagulation as membrane flux and feed water concentrations increased. Internal fouling resistance, which was not recovered by physical cleaning, was more than 70% of the total resistance at the range of the membrane flux more than $5m^3/m^2{\cdot}day$. In the combined process with coagulation, the cake layer resistance (Rc) increased to about 30-80% of total resistance. As the cake layer formed by coagulation floc was easily removed by physical cleaning, the recovery rate by physical cleaning was 54~90%. It was confirmed from the results that the combined process was more efficient to recover the filtration performance by physical cleaning due to higher formation ratio of reversible fouling, resulted in the mitigation of the frequency of chemical cleaning.