Effect of persulfate and persulfate/H2O2 on biodegradability of an anaerobic stabilized landfill leachate

• The effect of S2O82−/H2O2 on biodegradable characteristics of leachate was investigated.
• Biodegradability (expressed as BOD5/COD ratio) of stabilized leachate was enhanced.
• The process was found to be an efficient method for degradation of anaerobic stabilized leachate.
• Results obtained revealed that the new combined S2O82−/H2O2 is an efficient method for stabilized leachate treatment.

The current study investigated the effects of S2O82− and S2O82−/H2O2 oxidation processes on the biodegradable characteristics of an anaerobic stabilized leachate. Total COD removal efficiency was found to be 46% after S2O82− oxidation (using 4.2 g S2O82−/1 g COD0, at pH 7, for 60 min reaction time and at 350 rpm shaking speed), and improved to 81% following S2O82−/H2O2 oxidation process (using 5.88 g S2O82− dosage, 8.63 g H2O2 dosage, at pH 11 and for 120 min reaction time at 350 rpm). Biodegradability in terms of BOD5/COD ratio of the leachate enhanced from 0.09 to 0.1 and to 0.17 following S2O82− and S2O82−/H2O2 oxidation processes, respectively. The fractions of COD were determined before and after each oxidation processes (S2O82− and S2O82−/H2O2). The fraction of biodegradable COD(bi) increased from 36% in raw leachate to 57% and 68% after applying S2O82− and S2O82−/H2O2 oxidation, respectively. As for soluble COD(s), its removal efficiency was 39% and 78% following S2O82− and S2O82−/H2O2 oxidation, respectively. The maximum removal for particulate COD was 94% and was obtained after 120 min of S2O82−/H2O2 oxidation. As a conclusion, S2O82−/H2O2 oxidation could be an efficient method for improving the biodegradability of anaerobic stabilized leachate.