Novel combined IME-O3/OH−/H2O2 process in application for mature landfill leachate treatment

Abstract

Traditional wastewater treatment methods are often insufficient in the case of mature landfill leachate. Therefore novel methods are in demand. Recently, internal microelectrolysis (IME) has been recognized as an effective method besides AOPs for refractory wastewaters treatment. This study investigated the efficiency of a novel combined three-step process (IME-O3/OH−/H2O2) applied to mature landfill leachate treatment. Waste iron chips and granulated activated carbon (GAC) from nut shells were used in the process. Ozone was applied in doses from 0.28 to 1.4 g/dm3, and the mass ratios of COD/H2O2 were as follows: 1/0, 1/0.5, 1/1 1/1.5, and 1/2. Results showed that the PC is a reasonable pretreatment process before IME. However, COD and TOC removal was up to 22.4% and 37.9%, respectively. It required no additional reagents (before IME acidification is needed). The best total COD removal in the IME process was for Fe/GAC ratio 20/80 g/g in 1 dm3 (76.7%). Studies on the sorption process on GAC showed a significant share in the IME process - 11.2–62.6% of total COD removal. That was an important observation since most other authors ignored the fact of sorption. For optimal parameters of the O3/OH−/H2O2, total COD removal was 95.4%. The values of TOC, absorbance UV254, and color were highly reduced by 91.2%, 94.7%, and 98.2%, respectively. Additionally, biodegradability has been significantly improved up to 0.36.