• 상하수도학회지
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• 제21권6호
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• pp.653-661
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• 2007

The Disinfectants/Disinfection By-products (D/DBP) Rule proposed by the US Environmental Protection Agency requires the implementation of enhanced coagulation as a control strategy for natural organic matter (NOM) removal and as a means of limiting the formation of all DBPs, i.e., not just the trihalomethanes and haloacetica acids. To control DBP formation, several best available technologies (BATs) were determined for removal of DBPs and DBP precursors. The enhanced coagulation is one of the BATs for DBP precursors removal. Treatment facilities that achieve a specified percent removal of total organic carbon (TOC) prior to the application of a continuous disinfectant or that achieve a residual TOC concentration < 2mg/L prior to the application of a continuous disinfectant are considered to be in compliance with enhanced coagulation. The enhanced coagulation was applied to raw water in Korea, the Han River. Raw water were examined and effects of different raw water qualities on enhanced coagulation were investigated. Three analyses were used for raw water characteristics, water quality measurement, molecular weight distributions, hydrophobic/hydrophilic fractionation. The Han River had the relatively low alkalinity and low organic carbon concentration. The results of molecular weight distributions showed significant portions of low molecular weight organics, which is very different from most water in USA. The alum doses for the required TOC removal guided from USEPA manual were quite low (i.e. 10~30 mg/L alum) for the water, probably due to the specific water quality of the Han River.

• 한국환경보건학회지
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• 제18권2호
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• pp.57-61
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• 1992

This study was made for enhanced removal of N and P by intermittented aeration Activated Sludge Process. Experiment were conducted to find the effects of aeration interval and nutrient removal efficiency. When applied aeration interval were 30~60 min, 2~4 h, 4~8 h, organic matter was not affected while phosphorous removal was aeration interval 30~60 min. Also, when applied mixing intensity were 15, 30, 45 and 60 rpm, organic matter was not affected while removal was maximum at 15 rpm. Total nitrogen and phosphorous removal were in the range of 76 and 85%. Density and MLSS of Sludge were in the range of 2.3~2.6 and 7198~7810 mg/l. Release of phosphorous from activated sludge under unaerobic condition was increased as pass time.

• 대한환경공학회지
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• 제35권5호
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• pp.381-387
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• 2013

UASB-ABF (Up-flow anaerobic sludge blanket-aerated bio-filter) 시스템을 이용한 하수의 혐기성처리 방법에서 질소와 인을 제거하는 공법에 대하여 연구하였다. 160일간의 UASB-ABF 시스템을 운영한 결과 유출수 반송을 통하여 TCOD뿐만 아니라, TN과 TP를 효율적으로 제거할 수 있었다. 무반송의 경우 UASB 반응조에서 유기물 제거효율은 64%에 머물었으나, 반송률 120%, 180%, 240%로 증가한 결과 각각 92%, 95%, 96%로 향상되었다. 반송률 180% 이상에서는 유기물 제거효율 증가폭은 크지 않았다. ABF 유출수 반송으로 TN 제거효율이 크게 향상되었다. TN 제거효율은 무반송 조건일 때 18%에서 82%로 향상되었으며, UASB에서 지속적인 유기물질 제거로 인하여 ABF에서 질산화효율은 안정적으로 95% 이상으로 타나났다. ABF 유출수 반송으로 TP 및 $PO{_4}^{3-}$-P 제거효율이 모두 향상되었다. TP의 경우 무반송에서는 거의 제거되지 않았으나, 반송률이 120%, 180%, 240%에서는 각각 51%, 63%, 71%로 향상되었고, 주로 UASB에서 제거되었다.

• 상하수도학회지
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• 제19권3호
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• pp.370-377
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• 2005

Dispersion of coagulant should be completed in a fraction of a second before the metal hydroxide precipitate has form. For the reason so-called pump diffusion flash mixing (PDFM) have been proposed, and PDFM is one of reasonable methods to quickly disperse the hydrolyzing metal salts. In this study, therefore, we attempt to understand the difference of removal characteristics of natural organic matter (NOM) between pump diffusion flash mixing (PDFM) and conventional rapid mixing (CRM) for coagulation in a water treatment system, and to enhance the removal of NOM through the improved mixing process. DOC and turbidity removal by PDFM higher than those by CRM, while SUVA value of water treated by PDFM was high as compared with that by CRM. Hydrophilic NOM was more effectively removed by PDFM than CRM, since charge neutralization effect increased by quick dispersion of coagulant. The DBP formation potentials due to NOM was effectively reduced by the improved mixing (i.e., PDFM) for coagulation and could be controlled through decrease in concentration of precursor rather than reduction of activity with disinfectant.

• 상하수도학회지
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• 제33권6호
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• pp.447-456
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• 2019

This study focused on natural organic matter and trihalomethane removal by ozonation with various ferrous concentration in surface water. Ozonation is more affected by injection concentration than reaction time. dissolved organic carbon removal rates in ozonation increased with the increase in ferrous concentration. The highest removal was obtained at 6 mg/L of ferrous concentration. When 1 mg/L of ferrous was added with 2 mg/L of ozone concentration, it was found to be a rapid decrease in specific ultraviolet absorbance at the beginning of the reaction because ferrous acts as a catalyst for producing hydroxyl radical in ozonation. As ozone concentration increased, trihalomethane formation potential decreased. When 2 mg/L of ozone was injected, trihalomethane formation potential was shown to decrease and then increase again with the increase in ferrous concentration.

• Membrane and Water Treatment
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• 제9권4호
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• pp.205-210
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• 2018

In this study, we investigated coagulants such as polyaluminum chloride (PACl) and ferric chloride ($FeCl_3$) and the combination of a coagulant and powdered activated carbon (PAC) for the removal of dissolved organic matter (DOM) from fish processing effluent to reduce membrane fouling in microfiltration. The efficiency of each pretreatment was investigated through analyses of dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm ($UVA_{254}$). Membrane flux and silt density index (SDI) analyses were performed to evaluate membrane fouling; molecular weight distributions (MWD) and fluorescence excitation-emission matrix (FEEM) spectroscopy were analyzed to assess DOM characteristics. The results demonstrated that $FeCl_3$ exhibited higher DOC and $UVA_{254}$ removals than PACl for food processing effluent and a combination of $FeCl_3$ and PAC provided comparatively better results than simple $FeCl_3$ coagulation for the removal of DOM from fish processing effluent. This study suggests that membrane fouling could be minimized by proper pretreatment of food processing effluent using a combination of coagulation ($FeCl_3$) and adsorption (PAC). Analyses of MWD and FEEM revealed that the combination of $FeCl_3$ and PAC was more efficient at removing hydrophobic and small-sized DOM.

• 한국환경보건학회지
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• 제31권2호
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• pp.99-106
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• 2005

The removals of organic matter, nitrogen and phosphate in wastewater were investigated with Sequencing Batch Reactor (SBR). Glucose and sodium acetate were Used for organic carbon source so as to know nutrient removal efficiency in proportion to MLSS concentration. In the case of glucose, the COD removal rate was $74\%,\;41\%\;and\;66\%$ in MLSS 5000, 3000 and 1000, respectively. On equal terms, the BOD was $57\%,\;21\%\;and\;38\%$, the T-N was $24\%,\;13\%\;and\;44\%$, and the T-P was $12\%,\;21\%\;and\;33\%$. As a result, the removal rate of organic materials showed the finest remove when MLSS was 5000, but the nutrient removal rate appeared as was best when MLSS was 1000. In the case of sodium acetate, the COD removal rate was $83\%,\;81\%\;and\;86\%$ in MLSS 5000, 3000 and 1000, respectively. On equal terms, the BOD was appeared by $76\%,\;82\%\;and\;92\%$, the T-N $57\%,\;42\%\;and\;78\%$, and the T-P $48\%,\;52\%\;and\;38\%$. As a result, organic and T-N removal rates were best when MLSS was 1000. But, the T-P removal rates were best when MLSS was 3000. Glucose was shown fast removal in reaction beginning, but screened by more efficient thing though sodium acetate removes organic matter, nitrogen and phosphate. Form of floc was ideal in all reactors regardless of carbon source and MLSS concentration. And its diameter was about $200\~500{\mu}m$.

• 상하수도학회지
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• 제11권4호
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• pp.43-53
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• 1997

In this research, the synthetic livestock wastewater was prepared to study the characteristics of organic matter removal, the change of VFA production, and the amount of gas production with respect to the change of ammonium nitrogen concentration in the waste using anaerobic fixed bed process, which is an anaerobic biofilm process. The HRT and operation temperature were 1 day and $35{\pm}1^{\circ}C$, respectively. Also, the characteristics of organic matter removal and the inhibitory effect on microorganism in the anaerobic process were studied on the organic loading and ammonium nitrogen concentration. The results obtained were as follows: For COD loading of $10kg/m^3$-day and five levels of ammonium nitrogen concentration ranging from 1,000 to 5,000 mg/L, organic removal efficiencies were about 81, 74, 67, 58, and 51%, and gas productions were 3,860, 3,520, 3,240, 3,020, and 2,790 ml/l-day, respectively. Average methane contents in the gas produced on COD loading of $10kg/m^3$-day was about 76%. Throughout the whole period of experiment, remaining VFA (as COD base) in the effluent was over 90% of remaining COD. This result indicated the inhibitory effect of high concentration of ammonium nitrogen through the facts that accumulated VFA was almost COD and organic removal efficiency decreased also with the increase of ammonium nitrogen. Especially, that implys which high concentration of ammonium nitrogen not only inhibits methane forming bacteria, but also acid forming bacteria.

• 한국환경과학회지
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• 제26권3호
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• pp.401-410
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• 2017

This study analyzed the changes in the concentrations of organic matters in constructed treatment wetlands, coming from discharge water from a sewage treatment plant and non-point pollutant sources during rainfall events. At the beginning of a rainfall event, a massive amount of particulate organic matter flowed in, and was removed from the sedimentation basin (S1, S2); dissolved organic matter was removed after passing through stepwise treatment processes in the wetland. During dry period in the wetland, the removal efficiency rate for COD and TOC was -21 and -7%, respectively; during the rainfall event, the removal efficiency rate for COD and TOC were 47 and 43%, respectively. The highly-concentrated organic matters that flowd in at the beginning of the rainfall event was stabilized by various structures in the wetland before water discharge. Cyanobacteria blooms annually at the confluence of the So-ok stream and Daecheong Lake. Therefore, it is expected that the wetland will contribute significantly to reducing cyanobacteria and improving water quality in the area.

• 한국수산과학회지
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• 제50권3호
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• pp.250-256
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• 2017

This study investigated the removal efficiency of organic matter and nitrogen from fish farm effluent by hydraulic retention time (HRT) using an upflow biological filter (ANR system) reactor. The recycling time and influent flow in the reactor were controlled to 14.8, 7.4, 5.5 and 3.2 h to evaluate HRT. In addition, each reactor was coupled to a fixed bed upflow filter charged with media. The results showed that removal efficiency was ${\geq}95%%$ with an HRT of 5.5 h, and nitrification efficiency was reduced to 81% with an HRT of 3.2 h, although nitrification efficiency temporarily decreased due to the shock load as HRT decreased. Total nitrogen removal rate was also reduced to about 65% with an HRT of 3.2 h, which was considered a washout effect of nitrifying and denitrifying microorganisms by increasing the shearing force to the filter media, which decreased organic matter and nitrogen removal efficiency.