• Journal of Korean Society of Water and Wastewater
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• v.20 no.4
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• pp.559-571
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• 2006

The overall objective of this research was to find out the interrelation of coagulant and organic matter during rapid mixing process and to identify the change of organic matter by mixing condition and to evaluate the effect of coagulation pH. During the coagulation, substantial changes in dissolved organics must be occurred by coagulation due to the simultaneous formation of microflocs and NOM precipitates. Increase in the organic removal efficiency should be mainly caused by the removal of microflocs formed during coagulant injection. That is, during the mixing period, substantial amount of dissolved organics were transformed into microflocs due to the simultaneous formation of microflocs and NOM precipitates. The results also showed that 40 to 80% of dissolved organic matter was converted into particulate material after rapid mixing process of coagulation. During the rapid mixing period, for purewater, formation of dissolved Al(III) (monomer and polymer) constant by rapid mixing condition, but for raw water, the species of Al hydrolysis showed different result. During the rapid mixing period, for high coagulant dose, Al-ferron reaction increases rapidly. At A/D(Adsorption and Destabilization) and sweep condition, both $Al(OH)_3(s)$ and dissolved Al(III) (monomer and polymer) exist, concurrent reactions by both mechanism appear to cause simultaneous precipitation.

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.1015-1020
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• 2007

A simple approach to prepare arrays of Au/TiO2 composite nanoparticles by using Au-loaded block copolymers as templates combined with a sol-gel process is described. The organic-inorganic hybrid films with closely packed inorganic nanodomains in organic matrix are produced by spin coating the mixtures of polystyrene-block-poly(ethylene oxide) (PS-b-PEO)/HAuCl4 solution and sol-gel precursor solution. After removal of the organic matrix with deep UV irradiation, arrays of Au/TiO2 composite nanoparticles with different compositions or particle sizes can be easily produced. Different photoluminescence (PL) emission spectra from an organic-inorganic hybrid film and arrays of Au/TiO2 composite nanoparticles indicate that TiO2 and Au components exist as separate state in the initial hybrid film and form composite nanoparticles after the removal of the block copolymer matrix.

• Journal of Soil and Groundwater Environment
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• v.10 no.1
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• pp.6-12
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• 2005

Contamination of soils and groundwater by leakage of petroleum compounds from underground storage tanks (USTs) has become great environmental issues. Conventional methods such as soil vapor extraction (SVE) used for the remediation of unsaturated soils contaminated with volatile organic compounds might not be applied for the removal of semi-volatile organic compounds such as diesel fuels and PCBs, which have low volatility and high hydrophobicity. The objective of this study is to develop a hot air injection method to remove semi-volatile compounds. Additionally, operation parameters such as temperature, air flow rate, and water content are evaluated. Experimental results show that diesel ranged organics (DROs) are removed in the order of volatility of organic compounds. As expected, removal efficiency of organics is highly dependent on the temperature. It is considered that more than $90\%$ of organic contaminants whose carbon numbers range between 17 and 22 can be removed efficiently by the hot air injection-extraction method (modified SVE) over the $100^{\circ}C$. It is also found that increased air flow rate resulted in high removal rate of contaminants. However, air flow rate over 40 cc/min is not effective for the operation aspects, due to mass transfer limitation on the volatilization rate of the contaminants. The effect of the water content on the decane removal is minimal, but some components show large dependence on the removal efficiency with increasing water content.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1263-1271
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• 2000

This study investigated the floc structure and removal of turbidity and organic matter by alum coagulation. Results of this study indicated that sweep floc and charge neutralization area were shifted to more acidic region than that in the Amirtharajah's diagram. This was caused by organic matter present in the raw water. Removal regions of turbidity and organic matter were generally overlapped. However, organic matters was removed better at lower pH than turbidity. Floc structure was characterized by measuring fractal dimension and volume diameter using AIA and SALLS. SALLS method was found to be more reliable than AIA method. Floes in sweep floc region had larger size and fractal dimension than flocs in charge neutralization region. As pollutant removal increased, larger fractal dimension and size of floc were measured.

• Journal of Environmental Health Sciences
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• v.19 no.2
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• pp.23-33
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• 1993

The anaerobic digestion of organic synthetic wastewater in anaerobic fluidized bed bioreactor (AFBBR) and anaerobic fluidized packed bed bioreactor (AFPBBR) was studied. This study was conducted to evaluate efficiency and reliability of two reactor. Experiment was performed to find the effect of upflow rate with AFBBR and the height of packed bed with AFPBBR. As a result, this program obtained several conclusion. These are given as follows: As applied the upflow rate increased in AFBBR the produced volume of biogas increased, while the gas production and COD removal decreased at above 0.3 m$^3$/h. When a upflow rate is 0.4 m$^3$/h in AFBBR the volatile suspended solid (VSS) became significantly increased. At an organic loading rate from 0.1 to 0.4 of upflow rate in AFBBR, the methane yield was 1.5584 m$^3$CH$_4$/kgCOD removed, and the observed cell yield coefficient was 0.0933 gVSS/gCOD. In case of AFPBBR, the results showed also that 20 cm of height of packed bed was superior to other in the aspect ot biogas production, the content of methane and COD removal. At 20 cm of height, the profile of microorganisms was stable, while at 30 cm the VSS of effluent became higher than AFBBR. Though COD removal of AFPBBR increased with packed bed, COD removal deteriorate with over packing because the loss of pressure became higher in the reactor. At an organic loading rate from 20 to 40 cm of packed bed in-AFPBBR, the methane yield was 2.5649 m$^3$CH$_4$/kgCOD removed, and the observed cell yield coefficient was 0.0506 gVSS/gCOD. Based upon the results obtained, it is suggested that AFBBR and AFPBBR is the most effective conditions at 0.3 m3/h of upflow rate, the 20cm of packed bed, respectively. The rate constant are summarized as follow:

• Journal of Environmental Science International
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• v.16 no.6
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• pp.671-675
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• 2007

The objective of this study was to clarify the characteristics of the removed micropollutant since the breakthrough of adsorption ability was occurred in biological activated carbon(BAC) process. The removal efficiency of DOC (Dissolved Organic Carbon) was 36 % in the breakthrough of BAC occurred by NOM (Natural Organic Matter). The most of removal DOC was found out the adsorbable and biodegradable DOC (A&BDOC). But it was not clear to remove by any mechanism because A&BDOC have simultaneously the adsorption of activated carbon and biodegradation by microorganism in BAC. The removal of bromophenol was examined with BAC and rapid sand filter, for investigation of DOC removal mechanism in the breakthrough of BAC. In this experiment, BAC filter has been operated for 20 months for the treatment of reservoir water. The BAC filter was already exhausted by NOM. Bromophenol, adsorbable and refractory matter, was completely removed by BAC filter. Therefore, it might be removed by the adsorption in BAC. Adsorption isotherms of bromophenol were compared to two BACs which was preloaded with 500 daltons and 3,000 daltons of NOM. BAC preloaded with 3,000 daltons of NOM was not decreased to the adsorbability of bromophenol but BAC preloaded with 500 daltons of NOM was greatly decreased to it. These result indicated that NOM of low molecular weight can be removed by adsorption after a long period of operation and the breakthrough by NOM in BAC. Therefore, micropollutants might be removed through adsorption by saturated BAC.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.377-384
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• 2005

Algae causes not only the eutrophication of lake, but also the deterioration of drinking water process. Especially, algogenic organic matters(AOM) are assumed as disinfection by-products(DBPs) precursors like humic and fulvic acids. In this study, it was investigated the characteristics changes of algogenic organic matter(AOM) by prechlorination and coagulation treatment. Evaluation of enhanced coagulation and applicability of UV oxidation process were also evaluated as the drinking water treatment system for the eutrophicated water source. prechlorination was effective process for algae removal but caused releasing of dissolved organic matter(DOC) into water due to the destruction of algae's cell. In coagulation treatment with Fe(III) coagulant, reaction pH is an important factor for the removal of AOM and triholomathanes(THMs). At pH 5, removal efficiency of DOC and THMs were dramatically improved by 50% and 28%, respectively, in comparison with the conventional coagulation treatment at about pH 7. Photo-Fenton($UV/H_2O_2/Fe^{3+}$) process among the UV oxidations is the most effective system to remove AOM, but its removal efficiency was lower than that of enhanced coagulation treatment at pH 5.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.729-734
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• 2012

During chlorination processes dissolved organic nitrogen (DON) can form toxic nitrogenous disinfection byproducts and organic chloramines which have little or no bactericidal activity. DON needs to be removed before chlorination processes to reduce the formation of those products. This study investigated the removal of DON from surface water and reclaimed water by coagulation with aluminum sulfate (alum) and a cationic polymer (polyDADMAC). Removal characteristics of dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm ($UVA_{254}$) were compared with that of DON. Coagulation with alum removed DON, DOC, and $UVA_{254}$ with similar trends, but the removal of $UVA_{254}$ was highest. A dual coagulation strategy of alum and cationic polymer improved the removal of DON. Coagulation with cationic polymer alone was not effective due to its narrow range of charge neutralization. DON in reclaimed water was easier to remove than that in surface water, and higher molecular weight fraction (>10,000 Da) of DON was preferentially removed.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.279-284
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• 2013

In this study, the feasibility of a single-stage thermophilic aerobic process for the treatment of high-strength food wastewater produced from the recycling process of food wastes was examined to substitute anaerobic digestion process. Also, the removal and stability of thermophilic aerobic process were assessed according to the changes of hydraulic retention times (HRTs) and organic loading rates (OLRs). When the OLR increased from 9.2 to $37.2kgCOD/m^3d$, a pH value in R1 (HRT : 5 d) significantly decreased to 5.0, due to the organic acid accumulation. On the other hand, the pH value in R2 (HRT : 10 d) was stable and R2 showed the high removal of COD, organic acid and lipid, even though the OLR increased from 4.6 to $18.6kgCOD/m^3d$. In R1, the COD loading rates for COD removal was suddenly dropped, as the COD loading rate increased from 18.6 to $28.4kgCOD/m^3d$. In contrast, R2 showed that the COD loading rates for COD removal increased with regard to increment in the loading rates of 3.61, 7.05, 9.43 and $12.2kgCOD/m^3d$, indicative of the high COD removal efficiency. Therefore, the results demonstrated that over 10-d HRT, the high concentration of raw food wastewater was efficiently treated in the single-stage thermophilic aerobic process.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.629-637
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• 2000

A two-phase anaerobic reactor with a submerged microfiltration system was tested for its ability to produce methane energy from organic wastewater. A membrane separation system with periodic backwashing with compressed air was submerged in the acidogenic reactor. The cartridge type of microfiltration (MF) membrane with pore size of $0.5{\mu}m$ (mixed esters of cellulose) was tested. An AUBF (Anaerobic Upflow Sludge Bed Filter: 1/2 packed with plastic media) was used for the methanogenic reactor. Soluble starch was used as a substrate. The COD removal was investigated for various organic loading with synthetic wastewater of 5,000 mg starch/L. When the hydraulic retention time (HRT) of the acidogenic reactor was changed from 10 to 4.5 days, the organic loading rate (OLR) varied from 0.5 to $1.0kg\;COD/m^3-day$. When the HRT of the methanogenic reactor was changed from 2.8 to 0.5 days, the OLR varied from 0.8 to $5.8kg\;COD/m^3-day$. The acid conversion rate of the acidogenic reactor was over 80% in the 4~5 days of HRT. The overall COD removal efficiency of the methanogenic reactor showed over 95% (effluent COD was below 300 mg/L) under the highly fluctuating organic loading condition. A two-phase anaerobic reactor showed an excellent acid conversion rate from organic wastewater due to the higher biomass concentration than the conventional system. A methanogenic reactor combined with sludge bed and filter, showed an efficient COD and SS removal.