• Journal of the Korean Applied Science and Technology
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• v.16 no.1
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• pp.59-65
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• 1999

For a cosmetic plant wastewater containing surfactants of high concentration, adsorption treatment by granular activated carbon(GAC) having different pore size distribution was studied. Three sorts GACs were used and regenerated afterwards with methanol. Experiments were composed of batch process and column test for both virgin and regenerated GACs. Following conclusions were drawn from the study: Methylene blue activating substance(MBAS) adsorption data from the batch tests for three GACs are described well by BET isotherm and Freundich isotherm. Simulation with the BET isotherm shows that maximum adsorption appears to be affected not only by specific surface area but also by pore size distribution. Maximum adsorption from the BET isotherm for MBAS appears to diminish as the number of reactivation increases. The diminishing ratio of maximum adsorption appears to decrease as the pore size decreases. Recovery ratio of the methanol by vacuum evaporation from the spent methanol ranges from 95% to 97%.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.4
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• pp.285-292
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• 2021

Osmotic power is to produce electric power by using the chemical potential of two flows with the difference of salinity. Water permeates through a semipermeable membrane from a low concentration feed solution to a high concentration draw solution due to osmotic pressure. In a pressure retarded osmosis (PRO) process, river water and wastewater are commonly used as low salinity feed solution, whereas seawater and brine from the SWRO plant are employed as draw solution. During the PRO process using wastewater effluent as feed solution, PRO membrane fouling is usually caused by the convective or diffusive transport of PRO which is the most critical step of PRO membrane in order to prevent membrane fouling. The main objective of this study is to assess the PRO membrane fouling reduction by pretreatment to remove organic matter using coagulation-UF membrane process. The experimental results obtained from the pretreatment test showed that the optimum ferric chloride and PAC dosage for removal of organic matter applied for the coagulation and adsorption process was 50 mg/L as FeCl₃ (optimum pH 5.5). Coagulation-UF pretreatment process was higher removal efficiency of organic matter, as also resulting in the substantial improvement of water flux of PRO membrane.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.7
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• pp.385-390
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• 2017

This study investigated removal characteristic of soluble Cs in water by RPT (Radioactivity pollutant treatment) with coagulation and sedimentation. The RPT conducted with various chemical and natural coagulants to remove the soluble Cs which consisted pre-adsorption, Sedimentation and post-adsorption. Natural absorbent included Illite and zeolite. Especially, Illite divided LPI (Large Particle Illite) and SPI (Small Particle Illite) by grain size. Also, Chemical coagulants included high basicity PAC (poly aluminum chloride). The adsorbent had a plate structure mainly composed of quartz, albite and muscovite. The surface area were $4.201m^2/g$ and $4.227m^2/g$ and the particle sizes were $197.4-840.9{\mu}m$ and $3.28-53.57{\mu}m$, respectively. The adsorption efficiency of the natural Illite was 82.8% for LPI and 85.6% for SPI. The removal efficiency of turbidity, which was an indirect indicator of adsorbent recovery, was 96.4% and 98.3%, respectively.

• 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 Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.91-99
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• 2007

It is well-known that the presence of NOM (natural organic matter) in water has a negative effect on removing taste and odor compounds by activated carbon adsorption. Therefore, various means such as enhanced coagulation are applied to reduce the NOM. The presence of taste & odor compounds in drinking water even parts per trillion, is enough to generate customer dissatisfaction. Therefore, the aim of this study was to evaluate carbon usage rate (CUR) for conventional coagulation (CC) and enhanced coagulation (EC) in order to improve the efficiency of adsorption of taste and odor compounds. Also, Effect of CC and EC on molecular weight fraction and the early stage breakthrough of 2-MIB and Geosmin are evaluated. When the enhanced coagulation was adapted for pretreatment for activated carbon adsorption the operation period could be prolonged by 3.5~4 times. CUR for CC was about 2 times greater than CUR for EC and this means that EC has more adsorption capacity than CC. To analyze effect of EC and CC on breakthrough of 2-MIB quantitatively, adsorbed NOM mass was calculated based on unit mass of activated carbon. In the early stage breakthrough of 2-MIB, total adsorbed NOM was 23.72mg/g for CC and 34.56mg/g for EC. Therefore, it is shown that the early breakthrough term of 2-MIB and Geosmin was improved due to increased adsorbability. The low-molecular-weight NOM (500~2000Da) compounds were the most competitive, participating in direct competition with 2-MIB for adsorption site.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.172-173
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• 2019

As the damage to fine dust increased, the Republic of Korea designated fine dust as a social disaster. The composition of the fine dust is composed of carbon, sulfate, nitrate, ammonium and minerals. The cause of fine dust is naturally generated by dirt, pollen, etc. In addition, there are artificial causes such as gaseous vehicle exhaust gas emitted from the use of fossil fuel. When fine dust enters the human body through breathing, it causes various respiratory diseases and skin diseases. In IARC, fine dust was designated as a carcinogen group 1. In this research, we tried to adsorb fine dust by physical adsorption using powdered activate carbon. Powdered activate carbon is a powdered activated carbon activated in a carbonized state. Porous material with high specific surface area and low density. Experimental items were tested for density, water absorption, and fine dust concentration according to the PAC addition ratio. Basic experiments were carried out to fabricate the fine dust adsorption matrix.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.523-529
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• 2008

Algal blooms in a local eutrophic lake often produces the musty and earthy taste & odor problems. Since the odor causing compounds(OCCs) including geosmin and 2-MIB have their own volatility, the OCCs can be removed from water by air stripping methods. Removal of TON(threshold odor number) as an index for OCCs could be fitted well with the first order equations($R^2=0.9$ above), where the air stripping coefficient of TON, k was in the range between 0.0055 and 0.0097 according to the aeration time. k within 30min aeration tests was 0.0097, while it was 0.0055 where the aeration time extended to 150min. With 15 mg/L of PAC, removal of TON was not simulated with 1st order equation within 30min aeration. Within 30min aeration, OCCs rather than geosmin and/or 2-MIB could be removed easily by air stripping or PAC adsorption, while OCCs such as geosmin and/or 2-MIB could be removed slowly by air stripping after 30min aeration. Geosmin and 2-MIB were not readily removed by air stripping(k of them were 0.0018~0.0047 and 0.0018~0.0034, respectively at different air flow rates). Geosmin could be removed by air stripping a little better than 2-MIB.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.443-451
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• 2012

Wastewater treatment plants need to reduce phosphorus in order to meet increasingly stringent regulations on phosphorus. This study evaluated the feasibility of dolomite as a coagulation aid to enhance phosphorus removal from secondary treated wastewater by chemical coagulation. Standard jar tests were conducted to evaluate the effect of dolomite addition on a coagulation process for phosphorus removal and to determine the optimum doses of coagulants and dolomite. Coagulants used with dolomite yielded a significant improvement in phosphorus removal and reduced total phosphorus concentrations below 0.02 mg/L in wastewater effluent. Dolomite has played an important role in enhancing phosphate adsorption and increasing pH, as a coagulation aid. The maximum removal efficiency of phosphorus in this study was yielded at 25 mg/l of dolomite and 20 mg Al/L of PAC dose. However, considering economic aspects, the optimum doses of dolomite and PAC were 10 mg/L and 15mg Al/L, respectively. Consequently, dolomite, a coagulation aid, can be used in coagulation processes to enhance the removal of phosphorus.

• Journal of environmental and Sanitary engineering
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• v.20 no.3 s.57
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• pp.36-43
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• 2005

Prior to the study of the sewage treatment methods, water quality for Gwangju sewage of fluent was investigated from January to December, 2004 for sewage water reuse. Monthly mean values of BOD, SS, turbidity, total phosphorus and color were 4.1 mg/L, 2.9 mg/L, 0.8 NTU, 1.3 mg/L, and 27 unit, respectively. Jar-test was performed to investigate the removal efficiency of pollutants under the coagulation conditions of fast mixing for 5 min, slow mixing for 15 min and precipitation for 1hr. Here, alum and polyaluminium chloride (PAC) were used as coagulants to reduce color, turbidity, total phosphorus (TP) and total organic carbon (TOC) in sewage effluents. The results showed that PAC gave better efficiency in removing turbidity and dissolved phosphorus than alum. It was also found from the relative molecular weight (RMW) distribution analysis that organic matter over 1,000 Dalton (Da) was easily removed by coagulation and subsequently MF treatment, while it was not effective for less than 500 Da. Based on tis result, Natural organic matter (NOM) with lower molecular weight (< 500 Da) may cause harmful disinfectant by-product (DBP) after chlorine treatment. Thus, activated carbon adsorption seems to be required for the complete removal of DBP in the hybrid system.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.5
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• pp.609-618
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• 2009

Repeated phenol spill in the Nakdong River has been a big issue in Korea since 1991. In this study, treatment of phenol in each water treatment process and total water treatment system is evaluated. Phenol was highly volatile, easily oxidized by ozone, and readily absorbed onto GAC. When there was phenol of 0.3mg/L in water, by ozonation of 1mg/L or by GAC adsorption with EBCT of 10minutes or longer, it could be treated to lower than 0.005mg/L, the national drinking water standard of phenol. Even when a sufficient contact time(70minutes) was allowed, only 35 to 40% of phenol could be removed by powdered activated carbon(PAC). Based on the test results, it can be concluded that 1.0mg/L or less concentration of phenol can be treated at the plants adopting the combination process of ozone and GAC down to the safe level. In this study, removal characteristics for phenol were evaluated with the existing pilot plant and demo plant in different advanced water treatment processes(AWTPs). In the future, studies on changes in oxidation and adsorption characteristics caused by competitive matters such as DOC and removal characteristics by other various AWTPs including ozone/filter adsorber need to be performed.