• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1083-1091
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• 2000

The objective of this study is to develop effective and economical treatment processes for the removal of non-biodegradable organics by reusing the sludge generated from Fenton's Oxidation Process. It was found that about 50% of coagulants and 50% of catalyst can be reduced by reusing the sludge generated from Fenton's Oxidation Process. It was also found that the amount of sludge generation can be reduced in coagulation process and Fenton's Oxidation Process. From the results of bench-scale test, it was found that the average removal efficiency increased to 8.5% and the amount of sludge generation was reduced up to 35% by reusing the sludge as coagulant. The average organic removal efficiency increased to 5.3% and the amount of sludge generation was reduced up to 14% by reusing the sludge as catalyst in Fenton's Oxidation. It can be concluded that the reuse of sludge generated from Fenton's Oxidation Process would be reduced cost of chemical consumption and Fenton's sludge treatment.

• Journal of Life Science
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• v.9 no.6
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• pp.692-697
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• 1999

For further removal of non-biodegradable CODs and color in biologically treated distillery waster water, we selected a chemical treatment with Fe(III) and cationic polymers and then another chemical treatment with Fenton reagent. We developed Pregenerated Bubble Flotation(PBF) to effectively remove the chemical sludge from each chemical reaction process. The flotation unit was constructed with hydraulic loading rate, 7 ㎥/$m^2$.hr. The CODMn and suspended solids (SS) in biologically treated distillery waste water were reduced by the first PBF from 310-1096 mg/L to 141-303 mg/L and from 160-990 mg/L to 48-385 mg/L, respectively. Again, after the Fenton reaction process, floated SS was skimmed off at the top of the flotation unit and the final effluent was directly discharged without any tap water dilution. The quality of final effluent can be below 40 mg/L-CODMn but IISan Distilery has been maintained effluent quality of 73 mg/L-CODMn and 10-80 mg/L-SS. The chemical cost was saved by more than 30% as compared with that of prior process.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.4
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• pp.395-406
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• 2010

In this study, anaerobic digestion, electro-oxidation and electro-fenton oxidation processes were investigated to reduce oily refinery sludge. Anaerobic digestion process was not suitable for oily activated sludge reduction because of characteristics itself and, as experimental results revealed, reduction efficiency was low for electro-oxidation process. However, 40% total suspended solid reduction of oily activated sludge was obtained by electro-fenton oxidation process, operating at pH=1, 0.5 A and $Fe^{2+}$:$H_2O_2$ ratio = 1:30. In addition, higher reduction efficiency was obtained as reaction time was increased (30, 60, 90, 120 min) despite of low $H_2O_2$ concentration. From the results, it has been investigated that electro-fenton oxidation is efficient process for oily activated sludge reduction.

• Resources Recycling
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• v.9 no.1
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• pp.36-43
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• 2000

This study was carried out for treatment and reuse of inorganic sludge from Fenton process at B dyeing wastewater treatment plant. The parameters for pilot-scale treatment system were derived from the results of this study. It was found that $COD_{cl}$ of the treated effluent became lower than 100 mg/l approximately on the optimal reaction condition. 2nd sludge which was generated after redissolving sludge was analyzed, and it showed that reduction ratio of ash in 2nd sludge and total dry sludge weight in comparison with current sludge were 85% and 65%. Also Fe salt in sludge was redissolved about 90~95% of initial Fe by weight. It was estimated almost ￦350,000,000 for sludge reuse process. It was estimated saving of about ￦1,300,000 per day (￦420,000,000 per year) in operating cost based on 30,000 $m^3$/d treatment, which these were about ￦430,000 per day in chemical, ￦1,100,000 per day in sludge transportation and ￦200,000 per day in equipment maintenance. Payback period with interest charge for investment cost was estimated about 10.5 months. Also, net present value (NPV) was ￦792,000,000 and internal rat of return (IRR) was about 110%.

• Clean Technology
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• v.5 no.1
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• pp.49-61
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• 1999

Fenton's oxidation can improve the biodegradability of refractory organic wastewater by generating $OH{\cdot}$ which is one of the most reactive species. Fenton's reagent is used to treat a variety of industrial waste containing a range of toxic organic compounds. But this process cannot be economical because of high chemical cost of $H_2O_2$, ferrous ion solution and high sludge disposal cost. In this study, we proposed a modified Fenton's oxidation process which can reduce the reagent cost and obtain better removal efficiencies with less Fenton's reagents, and have a good potential of sludge recycling. In modified Fenton reaction, ferrous ion solution is adjusted to optimal pH with NaOH. Then it added to the sample and reacted to $H_2O_2$. For the experiment, synthetic wastewater made of phenol, which is one of the typical water pollutants, was used and the ionic strength of this wastewater was controlled by adding $NaHCO_3$. The effects of DO, ionic strength, and $H_2O_2$ dosing methods were investigated. As a result, modified Fenton's treatment efficiencies are better than conventional Fenton's reaction treating leachate and dyeing wastewater. And modified Fenton's treatment efficiencies combined to the sludge recycling for a half of Iron dosage are as good as the conventional Fenton's for a normal Iron dosage.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.5
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• pp.669-678
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• 2009

The reduction of excess activated sludge from petrochemical plant was investigated by the electro fenton (E-Fenton) process using electrogenerated hydroxyl radicals which lead to mineralization of activated sludge to $CO_2$, water and inorganic ions. Factors affecting the disintegration efficiency of excess activated sludge in E-Fenton process were examined in terms of five criteria: pH, $H_2O_2/Fe^{2+}$ molar ratio, current density, initial MLSS (mixed liquid suspended solids) concentration, $H_2O_2$ feeding mode. TSS total suspended solid and $TCOD_{cr}$ reduction rate increased with the increasing $H_2O_2/Fe^{2+}$ molar ratio and current density until 42 and $6.7 mA/cm^2$, respectively but further increase of $H_2O_2/Fe^{2+}$ molar ratio and current density would reduce the reduction rate. On the other hand, as expected, increasing pH and initial MLSS concentration of activated sludge decreas TSS and $TCOD_{cr}$ reduction rate. The E-Fenton process was gradually increased during first 30 minutes and then linearly proceed till 120 minutes. The optimal E-Fenton condition showed TSS reduction rate of 62~63% and $TCOD_{cr}$ (total chemical oxygen demand) reduction rate of 55~56%. Molar ratio $H_2O_2/Fe^{2+} = 42$ was determined as optimal E-Fenton condition with initial $Fe^{2+}$ dose of 5.4 mM and current density of $6.7{\sim}13.3 mA/cm^2$, initial MLSS of 7,600 mg/L and pH 2 were chosen as the most efficient E-Fenton condition.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.184-190
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• 2005

A new VFAs production process from sewage sludge using Fenton's oxidation was investigated. Optimum concentrations of $H_2O_\;and\;Fe^{2+}$ as well as optimum reaction temperature for VFAs production were studied. In the presence of $Fe^{2+}$ as catalyst, the VFAs formation rate increased about 4 times compared to $H_2O_2$ oxidation process without $Fe^{2+}$. Optimum concentrations of $H_2O_2$ and $Fe^{2+}$ were 0.62 M and 0.007 M, respectively. VFAs formation reaction proceeded rapidly within 1 min and VFAs formed degraded partly to acetic acid and $CO_2$, which exhibited series reaction characteristics. Based on the economic aspect, reaction temperature of $25^{\circ}C$ and 10 min of reaction time were thought to be proper reaction conditions. The effect of initial pH in the range of $3{\sim}6.3$ on the VFAs formation was not observed.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.9-14
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• 2009

In this research, a polyester manufacturing company (i.e. K Co.) in Gumi, South Korea was investigated regarding the release of high concentrations of 1,4-dioxane(about 600 mg/L) and whether treatment prior to release should occur to meet with the level of the regulation standard (e.g., 5 mg/L in 2011). The pilot-scale (reactor volume, 10 $m^3$) treatment system using Photo-Fenton Oxidation was able to remove approximately 90% of 1,4-dioxane under the conditions that concentrations of 2,800 ppm $H_2O_2$ and 1,400 ppm $FeSO_4$ were maintained along with 10 UV-C lamps (240 ${\mu}W/cm^2$) illuminated during aeration. However, the effluent concentration of 1,4-dioxane was still high at about 60 mg/L. Thus, further investigation is needed to see whether the bench scale (reactor volume, 8.9 L) of activated sludge could facilitate the decomposition of 1,4-dioxane. As a result, 1,4-dioxane in the effluent has been decreased as low as about 2~3 mg/L. Consequently, Photo-Fenton Oxidation coupled with activated sludge process can make it possible to efficiently decompose 1,4-dioxane to keep up with that of the regulation standard.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.86-92
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• 2016

The possibility of the biological treatment of MBT wastewater generated from the vulcanization accelerator manufacturing process was investigated. MBT wastewater is not biodegradable because it hinders the activity of microorganisms, and approximately 10% of the total COD can be removed after a 7 day acclimation period. The optimal conditions of the MBT wastewater for the chemical pre-treatment was pH of 3.5 and the Fenton oxidation with the addition of $Fe^{3+}$ to the wastewater after agitation for 2 hours. The Fenton-treated MBT wastewater showed approximately 20% removal of COD when treated with the activated sludge process for the mixed paper wastewater and Fenton treated wastewater.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.153-160
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• 2005

There have been large areas of soil contaminated with high levels of explosives. For this experimental work, 2,4,6-trinitrotoluene (TNT) was tested as a representative explosive contaminant of concern in both aqueous and soil samples and its removal was evaluated using three different chemical treatment methods: 1) the classical Fenton reaction which utilizes hydrogen peroxide ($H_2O_2$) and soluble iron at pH less than 3; 2) a modified Fenton reaction which utilizes chelating agents, $H_2O_2$, and soluble iron at pH 7; and 3) a Fenton-like process which utilizes iron minerals instead of soluble iron and $H_2O_2$, generating a hydroxyl radical. Using classic Fenton reaction, 93% of TNT was removed in 20 h at pH 3 (soil spiked with 300 mg/L of TNT, 3% $H_2O_2$ and 1mM Fe(III)), whereas 21% removed at pH 7. The modified Fenton reaction, using nitrilotriacetic acid (NTA), oxalate, ethylenediaminetetraacetic acid (EDTA), acetate and citrate as representative chelating agents, was tested with 3% $H_2O_2$ at pH 7 for 24 h. Results showed the TNT removal in the order of NTA, EDTA, oxalate, citrate and acetate, with the removal efficiency of 87%, 71%, 64%, 46%, and 37%, respectively, suggesting NTA as the most effective chelating agent. The Fenton-like reaction was performed with water contaminated with 100 mg/L TNT and soil contaminated with 300 mg/L TNT, respectively, using 3% $H_2O_2$ and such iron minerals as goethite, magnetite, and hematite. In the goethite-water system, 33% of TNT was removed at pH 3 whereas 28% removed at pH 7. In the magnetite-water system, 40% of TNT was removed at pH 3 whereas 36% removed at pH 7. In the hematite-water system, 40% of TNT was removed at pH 3 whereas 34% removed at pH 7. For further experiments combining the modified Fenton reaction with the Fenton-like reaction, NTA, EDTA, and oxalate were selected with the natural iron minerals, magnetite and hematite at pH 7, based on the results from the modified Fenton reaction. As results, in case magnetite was used, 79%, 59%, and 14% of TNT was removed when NTA, oxalate, and EDTA used, respectively, whereas 73%, 25%, and 19% removed in case of hematite, when NTA, oxalate, and EDTA used, respectively.