Abstract: Action mechanisms of affecting factors in treating toxic organic wastewater,such as simulated phenol wastewater by Fenton reagent-modified fly ash were preliminarily investigated.Under conditions that at first rapid (stirring speed was 350 r/min) mixing 1 min at room temperature,and then slow (stirring speed was 50 r/min) stirring 10 min,and at last 30 min static precipitation,the optimal operating conditions of Fenton reagent treating simulated phenol wastewater (mass concentration was 100 mg/L) determined by coagulation mixing experiments are as follows:pH=4,FeSO₄ with mass fraction of 5% was 2 mL,and H₂O₂ with mass fraction of 3% was 5 mL.Under these conditions,the removal rate of phenol reached 85.2%.Furthermore,the removal of Fenton reagent to phenol could be significantly enhanced as long as modified fly ash in certain of dosage range.Removal rate of phenol could be up to 99.3% with the best dosage of 100 mg/L of the modified fly ash.Promotion action was explained by means of free radical oxidation and coagulation-adsorption-locculation two mechanisms.It also indicated that,with the comparison of other methods of phenol removal,Fenton reagent-modified fly ash system had more advantages,such as high efficiency,rapid response,low cost,and easy operation.Therefore,it has a good prospect for practical application. 

Key words: Fenton reagent, hydroxyl radical, phenol wastewater, modified fly ash