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Advanced Treatment of Pesticide-Containing Wastewater Using Fenton Reagent Enhanced by Microwave Electrodeless Ultraviolet.

Cheng G, Lin J, Lu J, Zhao X, Cai Z, Fu J - Biomed Res Int (2015)

Bottom Line: Under the optimal conditions, the reaction exhibited high mineralization degrees of organics, where COD and dissolved organic carbon (DOC) concentration decreased from 183.2 mg/L to 36.9 mg/L and 43.5 mg/L to 27.8 mg/L, respectively.Three main pesticides in the wastewater, as Dimethoate, Triazophos, and Malathion, were completely removed by the MWEUV/Fenton process within 120 min.The high degree of pesticides decomposition and mineralization was proved by the detected inorganic anions.

View Article: PubMed Central - PubMed

Affiliation: Shenzhen Academy of Environmental Sciences, Shenzhen 518001, China.

ABSTRACT
The photo-Fenton reaction is a promising method to treat organic contaminants in water. In this paper, a Fenton reagent enhanced by microwave electrodeless ultraviolet (MWEUV/Fenton) method was proposed for advanced treatment of nonbiodegradable organic substance in pesticide-containing biotreated wastewater. MWEUV lamp was found to be more effective for chemical oxygen demand (COD) removal than commercial mercury lamps in the Fenton process. The pseudo-first order kinetic model can well describe COD removal from pesticide-containing wastewater by MWEUV/Fenton, and the apparent rate constant (k) was 0.0125 min(-1). The optimal conditions for MWEUV/Fenton process were determined as initial pH of 5, Fe(2+) dosage of 0.8 mmol/L, and H2O2 dosage of 100 mmol/L. Under the optimal conditions, the reaction exhibited high mineralization degrees of organics, where COD and dissolved organic carbon (DOC) concentration decreased from 183.2 mg/L to 36.9 mg/L and 43.5 mg/L to 27.8 mg/L, respectively. Three main pesticides in the wastewater, as Dimethoate, Triazophos, and Malathion, were completely removed by the MWEUV/Fenton process within 120 min. The high degree of pesticides decomposition and mineralization was proved by the detected inorganic anions.

No MeSH data available.


Evolution of COD and DOC in MWEUV/Fenton. Experimental parameters: initial pH value of 5, H2O2 dosage of 100 mmol/L, and Fe2+ dosage of 0.8 mmol/L.
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fig5: Evolution of COD and DOC in MWEUV/Fenton. Experimental parameters: initial pH value of 5, H2O2 dosage of 100 mmol/L, and Fe2+ dosage of 0.8 mmol/L.

Mentions: Figures 5 and 6 present the evolution of COD, DOC, AOS, and COS with reaction time. Both the initial AOS and COS parameters were −2.32, indicating that organic compounds are at reduced state in wastewater. With the prolonging of reaction time, the concentrations of COD and DOC in wastewater gradually decreased, showing a strong oxidation of the organics. AOS and COS parameters increased to be positive, suggesting that strong mineralization occurred and highly oxidized intermediates are generated. Analyzing the different process phases, more oxidized organic intermediates were formed before 60 min of reaction without substantial mineralization, which is corroborated by rapid COD decrease and low DOC removal. After the gradual growth, the values of AOS and COS reached the plateau. Finally, the concentrations of COD and DOC decreased to 36.9 mg/L and 27.8 mg/L, respectively, with the AOS value of 2.73 and the COS value of 2.01. The results indicate that a high oxidation degree of pesticides related to the generation of some low molecular weight carbohydrates which are resistant to mineralization by hydroxyl radicals.


Advanced Treatment of Pesticide-Containing Wastewater Using Fenton Reagent Enhanced by Microwave Electrodeless Ultraviolet.

Cheng G, Lin J, Lu J, Zhao X, Cai Z, Fu J - Biomed Res Int (2015)

Evolution of COD and DOC in MWEUV/Fenton. Experimental parameters: initial pH value of 5, H2O2 dosage of 100 mmol/L, and Fe2+ dosage of 0.8 mmol/L.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4548131&req=5

fig5: Evolution of COD and DOC in MWEUV/Fenton. Experimental parameters: initial pH value of 5, H2O2 dosage of 100 mmol/L, and Fe2+ dosage of 0.8 mmol/L.
Mentions: Figures 5 and 6 present the evolution of COD, DOC, AOS, and COS with reaction time. Both the initial AOS and COS parameters were −2.32, indicating that organic compounds are at reduced state in wastewater. With the prolonging of reaction time, the concentrations of COD and DOC in wastewater gradually decreased, showing a strong oxidation of the organics. AOS and COS parameters increased to be positive, suggesting that strong mineralization occurred and highly oxidized intermediates are generated. Analyzing the different process phases, more oxidized organic intermediates were formed before 60 min of reaction without substantial mineralization, which is corroborated by rapid COD decrease and low DOC removal. After the gradual growth, the values of AOS and COS reached the plateau. Finally, the concentrations of COD and DOC decreased to 36.9 mg/L and 27.8 mg/L, respectively, with the AOS value of 2.73 and the COS value of 2.01. The results indicate that a high oxidation degree of pesticides related to the generation of some low molecular weight carbohydrates which are resistant to mineralization by hydroxyl radicals.

Bottom Line: Under the optimal conditions, the reaction exhibited high mineralization degrees of organics, where COD and dissolved organic carbon (DOC) concentration decreased from 183.2 mg/L to 36.9 mg/L and 43.5 mg/L to 27.8 mg/L, respectively.Three main pesticides in the wastewater, as Dimethoate, Triazophos, and Malathion, were completely removed by the MWEUV/Fenton process within 120 min.The high degree of pesticides decomposition and mineralization was proved by the detected inorganic anions.

View Article: PubMed Central - PubMed

Affiliation: Shenzhen Academy of Environmental Sciences, Shenzhen 518001, China.

ABSTRACT
The photo-Fenton reaction is a promising method to treat organic contaminants in water. In this paper, a Fenton reagent enhanced by microwave electrodeless ultraviolet (MWEUV/Fenton) method was proposed for advanced treatment of nonbiodegradable organic substance in pesticide-containing biotreated wastewater. MWEUV lamp was found to be more effective for chemical oxygen demand (COD) removal than commercial mercury lamps in the Fenton process. The pseudo-first order kinetic model can well describe COD removal from pesticide-containing wastewater by MWEUV/Fenton, and the apparent rate constant (k) was 0.0125 min(-1). The optimal conditions for MWEUV/Fenton process were determined as initial pH of 5, Fe(2+) dosage of 0.8 mmol/L, and H2O2 dosage of 100 mmol/L. Under the optimal conditions, the reaction exhibited high mineralization degrees of organics, where COD and dissolved organic carbon (DOC) concentration decreased from 183.2 mg/L to 36.9 mg/L and 43.5 mg/L to 27.8 mg/L, respectively. Three main pesticides in the wastewater, as Dimethoate, Triazophos, and Malathion, were completely removed by the MWEUV/Fenton process within 120 min. The high degree of pesticides decomposition and mineralization was proved by the detected inorganic anions.

No MeSH data available.