Assessment of Pretreatments for Highly Concentrated Leachate Waters to Enhance the Performance of Catalytic Wet Peroxide Oxidation with Sustainable Low-Cost Catalysts
Matured compost, derived from a mechanical and biological treatment (MBT) plant, was
used as a precursor to produce catalysts through hydrothermal and thermal carbonization, HC and
PC, respectively. HC and PC displayed suitable properties to act as catalysts in the catalytic wet
peroxide oxidation (CWPO) treatment of the highly polluted leachate waters generated in the same
MBT plant (TOC0 = 27 g L-1; COD0 = 60 g L-1; BOD5,0 = 23 g L-1). The influence of catalyst loading
and pH were studied, considering multiple additions of H2O2. The best experimental conditions
found were T = 80º C, pH0 = 3.0, 7.2 g L-1 of HC catalyst, 85.7 g L-1 of H2O2, added in five batches
in one-hour intervals between each addition. Under these experimental conditions, removals of 43%,
52%, 93%, 82%, 35%, 95% and 93% for the COD, TOC, BOD5, aromaticity, chlorides, turbidity and
color number (CN) were, respectively, observed. Ion exchange resins and coagulation–flocculation
were studied as pretreatment options to reduce the complexity of the leachate waters and enhance
the CWPO results. Both strategies resulted in higher mineralization and enhanced the consumption
efficiency of H2O2 (H2O2 ). The sequential treatment using coagulation–flocculation and CWPO with
PC catalyst showed the best results, achieving abatement of 94%, 70%, 98%, 93%, 31%, 96% and 95%
for COD, TOC, BOD5, aromaticity, chlorides, turbidity and CN, respectively.
This work was financially supported by project “VALORCOMP-Valorización de compost
y otros desechos procedentes de la fracción orgánica de los residuos municipales”, with reference
0119_VALORCOMP_2_P, through FEDER under Program INTERREG; Base Funding- UIDB/50020/2020
of the Associate Laboratory LSRE-LCM-funded by national funds through FCT/MCTES (PIDDAC);
CIMO (UIDB/00690/2020) through FEDER under Program PT2020 and national funding by FCT,
Foundation for Science and Technology and European Social Fund, FSE, through the individual
research grant SFRH/BD/143224/2019 of Fernanda Fontana Roman.
