The experiments focused on the Fenton treatment of humic substances (HS) in concentrated landfill leachate rejected by reverse osmosis (RO).The changes in dissolved organic matter by oxidation/coagulation were assessed by using gross organic parameters such as chemical oxygen demand (COD)

total organic carbon (TOC)

UV254 and COD/TOC molar ratio during the treatment with Fenton reagent.The results demonstrated that the humic substances removal efficiency (from 119% to 895%) was higher than that of COD (from 9.6% to 75.2%) and there was a good correlation between humic substances degradation and COD removal.This study showed that the oxidation efficiency controlled the coagulation efficiency

so high oxidation efficiency may cause relatively low coagulation.The change of (COD/TOC)oxid indicated that the oxidation reaction was ultimate degradation under the condition of pH= 20—40

［H2O2］>80 mmol.L-1

［Fe2+ ］= 40—160 mmol.L-1

reaction time 2h.The changes of (COD/TOC)coag illustrated that the oxidation state of the organic matter removed by coagulation was significantly higher than in the fresh landfill leachate under the above reaction conditions.