Degradation of Wastewater from Fragrance and Flavor Production and Phenol Industry by Fenton Reagent and Electro-Fenton

Abstract: The organic wastewater of fragrance and flavor production and phenol industry contains high CODCr (CODCr>4000 mg/L) or the compound (ammonia nitrogen, polycyclica romatich ydrocarbons, Bap,et.al) that could not be degraded by conventional biological wastewater treatment methods.The organic wastewater is harmful because it is high concentration, poisonous and difficult to degrade.It will poison the creature in the water, reduce the corps production and cause serious sickness if it is let out into the rivers without treatment.Traditional water treatment technology for highdensity refractory wastewater treatment is limited.So look for effective ways to solve the problem of sewage treatment, it is extremely meaningful. Fenton reagent by the role of H2O2 and Fe2+ generated OH,it has strong oxidation ability for the oxidation of refractory organic wastewater treatment.So Fenton reagent is the main wastewater treatment technology development directions.As adsorption,coagulation,extraction,methods in wastewater treatment effect was not obvious,therefore Fenton reaction was used to treat wastewater from fragrance and flavor production.After a series of experiments,effects of factors including pH value,dosage of H2O2 and FeSO4·7H2O,and reaction time to the CODCr removal efficiency were evaluated.Results showed that the CODcr and color of the wastewater were effectively removed by Fenton.The optimal operating conditions determined were at a pH value of 3,a dosage of H2O2 of 40 mL/L, a dosage of FeSO4·7H2O of 4.0 g/L,and the time of reaction of 3.0 h. The corresponding CODCr removal efficiency was 75%,color removal efficiency was 82%.The Fenton reaction was found to be effective for the treatment of wastewater from fragrance and flavor production.Electro-Fenton reagent as a class than the traditional Fenton reagent has good treatment effect.Oxidation of phenol in aqueous solution by electro-Fenton reactions has been studied using bipolar graphite electrodes filled with activated carbon.Effects of reaction parameters including pH value of the solution,dosages of ferrous ion, current of solution,and reaction time on phenol and CODCr removal were evaluated for the treatment of wastewater containing phenol of 100 mg/L at 25±1℃.Removal mechanisms were also investigated by analyzing the intermediate products using HPLC and GC-MS.Results showed that removal efficiencies of phenol and CODCr were 93%and 65% respectively at pH of 3.0 (±0.01),current of 0.30A,plate distance of 4 cm,a dosage of ferrous ion of 0.1 mmol/L,a dosage of granular activated carbon of 100 g, an reaction duration of 60 min, and an air flow rate of 10 L/min.When the reaction time was increased to 180 min,phenol in the wastewater was not below detection limit.Phenol removal efficiency decreased significantly when Na2CO3,a hydroxide radical scavenger, was added in the reactor, which indicates that both electro catalytic oxidation and radical oxidation contributed to the degradation of phenol.
Key words: Fragrance and Flavor; Phenol; Fenton reagent; electro-Fenton; Degradation efficiency;

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