Study On Treatment Of Refractory Organics In The Landfill Leachate By Potassium Ferrate Oxidation

Landfill leachate is known as a kind of refractory wastewater owing to lots of refractory organics and harmful components in it. Potassium ferrate was used to oxidize refractory organics in landfill leachate, and in order to improve the treatment effect, inorganic salts and phase transfer catalysts were added to increase the probability of reaction between potassium ferrate and organic matter.First, influences of potassium ferrate dosage, pH value, reaction time and initial concentration of the potassium ferrate on the treatment effect of landfill leachate were investigated. Results showed that CODCr removal rate could reach to36%, and UV-254value could decrease to6.64cm-1from initial10cm-1under the condition of potassium ferrate dosage of6g/L, pH of10, and reaction time of30min.Next, three kinds of inorganic salts (sodium silicate, sodium molybdate, and sodium phosphate) were added to the reaction respectively. Influences of dosage of inorganic salts, pH value, and reaction time on the treatment effect of landfill leachate were studied. Results showed that after adding inorganic salts, treatment effects of landfill leachate were better than that of no inorganic salts, and the influence rule of pH for the treatment effect and the optimum pH were all changed. The optimum dosage of inorganic salt was determined by the experiment:sodium silicate was4g/L, sodium molybdate was2g/L, and sodium phosphate was2g/L. By adding any one of three inorganic salts, CODCr removal rate all could reach more than45%, and UV-254all could drop to below6.11cm-1.Then four kinds of phase transfer catalysts—cetyl trimethyl ammonium bromide (CTAB), tetramethyl ammonium chloride (TMAC), benzyl trimethyl ammonium chloride (TMBAC) and manganese acetate were added respectively. Influences of dosage of phase transfer catalyst. pH value, reaction time and dosage of potassium ferrate on the treatment effect of landfill leachate were explored. Results showed that after adding phase transfer catalyst, treatment effects of landfill leachate were improved comparing with no phase transfer catalyst, and the influence rule of pH for the treatment effect and the optimum pH were all changed. The effect of CTAB’addition was best among four. CODCt removal rate could reach around55%, and UV-254could fall to5.72cm’1under the condition of dosage of CTAB of12mg/L, pH of3, reaction time of30, and dosage of potassium ferrate of6g/L. With adding phase transfer catalyst, the biodegradability of wastewater was enhanced obviously.Finally, influences of both phase transfer catalyst’and inorganic salt’ addition on the treatment effect of landfill leachate were explored. Results showed that when CTAB and sodium molybdate were both added, the treatment effect was best. And CODcr removal rate could reach around58%, UV-254value could reach5.8cm-1. Combination of phase transfer catalyst and inorganic salt could also increase the biodegradability of wastewater obviously, and inorganic salts played an important role in it.