Assessment of Pretreatments for Highly Concentrated Leachate Waters to Enhance the Performance of Catalytic Wet Peroxide Oxidation with Sustainable Low-Cost Catalysts

Abstract

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 = 80 °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 (ηH2O2). 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.

Removal of gaseous ammonia released from leachate by adsorption on carbon-based adsorbents prepared from agro-industrial wastes

“…Then, OS and MB were pyrolyzed to produce OS-P and MB-P pyrochars, respectively. Pyrolysis was conducted in a quartz tubular furnace (Thermconcept) under N2 continuous flow rate of 100 Ncm 3 min -1 up to 800 o C for 4 h, following the detailed methodology described in previous works (de Freitas Batista et al 2022;Diaz de Tuesta et al 2018).…”

“…Pyrochars are the solid chars remaining from one-step thermal decomposition (<900 o C and oxygen-limited atmosphere) of a carbon source and present high porosity development (Zhang et al 2019). Hydrochars are carbonaceous materials prepared by hydrothermal carbonization (HTC), a thermo-chemical process, which uses water, heat (<400 o C) and high pressure (Diaz de de Freitas Batista et al,2022). More novelty approaches consist in the use of catalyst and chemical agents in HTC to modify hydrochar's properties and improve their performance (Diaz de Susanti et al 2019).…”

Chemically Activated Hydrochars as Catalysts for the Treatment of Htc Liquor by Catalytic Wet Air Oxidation

“…Color number (CN) was evaluated following the methodology reported in the literature [32,33]. Firstly, spectral absorption coefficient (SAC i ) was determined by absorption (Abs i ) at 436, 525 and 620 nm wavelengths as SAC i (m − 1 ) = Abs i /x, where x refers to the path length of the cuvette used in measurements (0.01 m).…”

Biodegradation of Different Types of Bioplastics through Composting—A Recent Trend in Green Recycling

“…In contrast, landfilling produces greenhouse gases and creates environmental concerns. Landfilling not only produces greenhouse gases but also occupies and contaminates future agricultural land [22,23]. Therefore, composting would be a more profitable and desirable method for disposing of bioplastic waste.…”