An Innovative Approach to the IME Process Applied to Stabilized Landfill Leachate

Conventional wastewater treatment is often insufficient in the case of mature landfill leachate. Among novel methods internal micro-electrolysis (IME) has been recently recognized as an effective method for refractory wastewaters treatment. The aim of this study was the evaluation of the impact of various parameters (pH, time, types and ratios of Fe/GAC, H2O2 dose and time of application, soaking of GAC in LL) on the efficiency of the IME process applied to mature landfill leachate. As microelectrodes were used waste cast-iron chips and granulated activated carbon (GAC). Application of a multi-step treatment of leachates: PC>m-IME>m-IME/H2O2 resulted in 82.1% COD removal and significant increase in bio-degradability (BOD5/COD rose up to 0.39). The optimal parameters were established as follows: pH 3, 120 min, ratio Fe/GAC 40/10 g/g/dm3 and ratio COD/H2O2 = 1/2. Results showed that the PC is a reasonable pretreatment process before IME - improvement in total COD removal was up to 12.5%. COD removal in IME process in-creased with the increase in GAC dose only up to a certain level. Also too high doses of Fe negatively affected the efficiency of the IME process which shows that the efficiency depends not only on the dose, but also on the mass ratio of Fe/GAC. Addition of H2O2 significantly improved the COD removal effectiveness, especially when it was applied after 120 min of the m-IME process. Results showed also that soaking of GAC in LL before the process did not eliminate sorption process.