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 11.9% to 89.5%) 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= 2.0—4.0,>80 mmol·L-1,= 40—160 mmol·L-1,reaction time 2 h.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.
