• Environmental Engineering Research
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• v.13 no.4
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• pp.210-215
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• 2008

The present study investigates the effect of oxidation-reduction potential (ORP) and organic compounds on specific anaerobic ammonium oxidation activity (SAA) using batch experiments. The batch tests were based on the measurement of nitrogen gas production. The relationship between ORP and dissolved oxygen (DO) concentration was found to be ORP (mV) = 160.38 + 68 log [$O_2$], where [$O_2$] is the DO concentration in mg/L. The linear relationship obtained between ORP and SAA ($R^2$ = 0.99) clearly demonstrated that ORP can be employed as an operational parameter in the Anammox process. At ORP value of -110 mV, the SAA was $0.272{\pm}0.03\;g\;N_2-N\;(g\;VSS)^{-1}\;d^{-1}$. The investigation also revealed inhibitory effect of glucose on the SAA while acetate concentration up to 640 mg COD/L (corresponding to 10 mM) had stimulating effect on the SAA. However, acetate concentration beyond 640 mg COD/L had inhibitory effect on the Anammox activity. The results indicated that nitrogen rich wastewaters containing low level organic matter could be better treated by Anammox microorganisms in real-world conditions after some acidification process.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.171-177
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• 2020

To improve the nitrogen reduction capability of stormwater treatment systems subjected to intermittent saturation, organic materials are often added as filter media. However, these materials can be an additional source of organic carbon and increase the chemical oxygen demand (COD) in the outflow. In this study, different types of organic filter media were subjected to a batch leaching test to observe and quantify the release of COD. Results reveal that the initial pH of the tap water used for soaking which is 7.5-7.7 is conducive to the release of organics from the media to the leachate. The highest amount of COD released was observed in yard clippings and woodchip followed by compost and bark mulch. The leaching of organics also increased as the size of the media decreases due to higher surface area per volume. In addition, empirical regression analysis predicted that COD from these organic media will be exhausted from the material in 3-5 months to up to 26 months depending on the type of media. The results of this study can serve as a guide in estimating the potential release of COD in organic media in order to ensure their safe application in stormwater treatment facilities.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.5
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• pp.53-59
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• 2008

This study was carried out to investigate the effect of photocatalysis using $TiO_2$ and UV applied for the COD reduction of wastewater in linerboard mill. Trials were done to obtain the optimum addition amounts of $TiO_2$ and $H_2O_2$ to the wastewater and find an appropriate pH condition for photocatalysis on $TiO_2$ for degrading COD. The photocatalytic reaction was applied to the wastewater collected after secondary activated sludge treatment in WWTP of linerboard mill. The optimum application of photocatalysis reaction was obtained under the addition conditions of 2 g/L of $TiO_2$ and 200 mg/L of $H_2O_2$ at pH 3.0, respectively. The removal efficiency of $SCOD_{Cr}$ by photocatalytic treatment was 86.4 % and higher than Fenton treatment in which removal efficiency was 67.4 %. It was concluded that the photocatalytic process using $TiO_2$ and UV could be applied to the wastewater treatment in linerboard mill and also to the dramatic drop-off in NBDCOD load from wastewater of tertiary treatment in WWTP.

• Journal of Environmental Science International
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• v.5 no.1
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• pp.51-59
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• 1996

The purpose of this study was to evaluate the partial oxidation of the biological treatment plant effluents using Fenton's reagent as a pretreatment step prior to a tertiary biological oxidation of these effluents. Fenton's reagent was evaluated as a pretreatment process for inhibitory or refractory organics. Based on the Fenton oxidation system, the petrochemical wastewater treatment plant effluent was shown to have significant improvement in toxicity after oxidation with hydrogen peroxide. For example, at ranee of 42 ∼ 184 mg/L COD of petrochemical plant effluents, the COD removal efficiencies were from 38.2% to 60.1% after reaction with hydrogen peroxide 200 mg/L and Fe2+ 100 mg/L and reaction time was 30 minutes. The total TOC reduction were about 15.8∼22.4% with same test condition and difference between the overall removal rate and BOD/COD ratio after Fenton's oxidation estabilished in the biodegradation and otherwise meets the discharge standard or reuse for cooling tower make-up water.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.1
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• pp.13-21
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• 1996

For treating tannery wastewater containing high sulfate and heavy metals, test was performed to assess their performance, competition between SRB (sulfate reducing bacteria) and MPB (methane producing bacteria), and the activity of MPB according to change of chromium concentrations. COD removal efficiency was above 70% at VLR (volumetric loading rate) of 2.0 gCOD/I.day and HRT (hydraulic retention time) of 18hrs at $35^{\circ}C$. In the competition between SRB and MPB, about 15% of the removed COD was utilized by SRB in the begining, but it became 43% at the end. It indicated that MPB was strongly suppressed by the occurrence of significant sulfate reduction since a large electron flow was uptaken by SRB. For the entire experiment, removal efficiencies of chromium concentration were more than 90%. Despite high removal efficiencies of chromium concentration, performance of reactor did not change significantly during the experimental periods. Expecially, chromium (III) is tannery wastewater is less toxic than chromium (VI).

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.166-172
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• 2013

The purpose of this study is to evaluate the treatment ability of refractory organics in hot rolling precess waste water by redox(reduction and oxidation) reaction. Metal is oxidized in an aqueous solution to generate electron which can reduce water to generate hydroxy radical. These hydroxy radical is very effective to conduct hydrogen abstraction reaction and addition reaction to the carbon - carbon unsaturated link. The surface area of metal alloy reaction material is more than enough to get equilibrium at a single treatment. The efficiency of COD treatment by redox reaction showed maximum at mild pH of pH 7 and pH 6. But it was not effective in acidic atmosphere of pH 3, 4, 5 and basic atmosphere of pH 8 or over. Redox reaction system in much more helpful in a commercial coagulation sedimentation treatment than exclusive system.

• Advances in nano research
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• v.8 no.1
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• pp.1-11
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• 2020

In order to develop a new adsorbent for removal of formaldehyde from aqueous solution, surface modification of TiO₂ nanoparticles was performed with 2,4-Dinitrophenylhydrazine (DNPH) that have a strong affinity to the formaldehyde. Sodium dodecyl sulfate (SDS) surfactant was used to improve the DNPH grafting to TiO₂ surface. Modified adsorbents were characterized by SEM, TEM, XRD, EDX and FTIR. Since the COD level in wastewaters including formaldehyde is considerable, it is necessary to determine the COD content of the synthetic wastewater. In order to determine the optimal removal conditions, the effect of contact time (60-210 min), pH (4-10) and adsorbent dosage (0.5-1.5 g/L) on adsorption and COD removal efficiencies were studied, using response surface method. EDX and FTIR analysis confirmed the presence of nitrogen-containing functional groups on the modified TiO₂ surface. The maximum formaldehyde adsorption and COD removal efficiencies by modified TiO₂ were about 15.65 and 7.35% higher than the unmodified nanoparticles respectively. Therefore, the grafting of nano-TiO₂ with DNPH would greatly improve its formaldehyde adsorption efficiency. The optimum conditions determined for a maximum formaldehyde removal of 99.904% and a COD reduction of 94.815% by TiO₂/SDS/DNPH nanocomposites were: adsorbent dosage 1.100 g/L, pH 7.424 and the contact time 183.290 min.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.498-503
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• 2007

The performance of elutriated acid fermentation to evaluate the effects of microwave irradiation and pH control as pretreatment was investigated. The MW pH 7 reactor which was used the pretreated primary sludge as microwave irradiation was operated at pH 7 and $35^{\circ}C$. The EAF pH 9 reactor was operated at pH 9 and $35^{\circ}C$ without pretreatment. The SCOD and VFAs production rate were 0.17 gSeOD/gVSrem. and 0.27 gVFAs as COD/gVSrem. in MW pH 7 reactor, 0.16 gSCOD/gVSrem. and 0.24 gVFAs as COD/gVSrem. in EAF pH 9 reactor, respectively. VS and Volume reduction were 54% and 48% in MW pH 7 reactor, 54.6% and 36% in EAF pH 9 reactor, respectively. A comparison of the microwave irradiation and controlled pH in elutriated acid fermentation showed that the former is more efficient in SCOD and VFAs production and it rises to slightly higher reduction in the volume of the sludge. In addition, E. coli. was not detected in the wasting sludge of MW pH 7 reactor. Based on the results, microwave irradiation appeared to be one of the viable options for generating class A sludge. According to the batch tests, sequencing batch test which was used the pretreated primary sludge as microwave was performed at pH 7 and $35^{\circ}C$, SCOD production was 0.16 gSCOD/gVSrem., VS reduction and volume reduction were 64% and 63%, respectively.

• Journal of Environmental Impact Assessment
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• v.28 no.5
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• pp.471-482
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• 2019

Water treatment system filled with Bio-stone Ball (BSB) have been developed for the purification of polluted water in many rivers and lakes. The real-scale plants of BSB water treatment system was constructed for field application test and water purification evaluation in Maewha reservoir. The average water purification efficiencies of BSB watertreatment system shows BOD 70.3% (47.2~97.4%), COD 45.3% (26.1~64.7%), TOC 19.2% (8.5~50.0%), SS 82.8% (73.1~92.7%), Chl-a 80.4% (57.2~91.8%), TN 23.2% (6.4~39.5%), and TP 51.8% (-1.1~80.1%). BSB water treatment system shows very high at 70~80% in the water purification efficiencies of BOD, Chl-a, and SS. The average of pollution loading reduction by installation of BSB treatment system shows 39.2% for COD and 16.8% for TP. The water quality improvement rates (%) of the Maewha reservoir shows TOC 14.5%, COD 14.5%, Chl-a 12.5% and TP 25.1%. The BSB watertreatment system can be applied to many agricultural reservoirs and major rivers to deal with serious water pollution issues.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.313-321
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• 2000

This research is to remove heavy metals from AMD(Acid Mine Drainage) using AFMR(Anaerobic Floating Media Reactor) process. Two AFMR were operated at HRT(hydraulic retention time) of 3 days. COD/sulfate ratio from 0.3 to 0.8, temperature from $30^{\circ}C$ to $35^{\circ}C$, and alkalinity of 1.000mg/l(as $CaCO_3$). At COD/sulfate($SO{_4}^{2-}$) ratio of 0.5 and temperature of $35^{\circ}C$, the ratio of reduced sulfate($SO{_4}^{2-}$)/removed COD(mg/mg) kept about 1 and the reactor achieved 99.99% of Cr, Pb anee Fe, 98% of Cd, and 90% of Mn removal efficiencies, respectively. Decreasing temperature to $30^{\circ}C$ increased the ratio of reduced sulfate($SO{_4}^{2-}$)/removed COD(mg/mg) to 1.37. Amount of sulfate reduction maximized at the temperature of $30^{\circ}C$ and the COD/sulfate ratio of 0.4 in the influent and then removal efficiencies of heavy metals were 99.99% of Fe, 99.99% of Pb, 99,99% of Cr, 97.3% of Mn, 99.9% of Zn, 99.9% of Cd and 99.9% of Cu.