Pretreatment of sludge with sodium iron chlorophyllin-H2O2 for enhanced biogas production during anaerobic digestion

This study investigated a novel sodium iron chlorophyllin-H 2 O 2 (SIC–H 2 O 2 ) sludge pretreatment strategy before anaerobic digestion to enhance methane production. The efficiencies and mechanism of the proposed strategy to enhance sludge biodegradability were explored. The SIC–H 2 O 2 pretreatment could enhance the oxidation performance for sludge floc disintegration to dissociate TB-EPS into S-EPS increased SCOD to 521.38 mg/L. The increase of solubilization and release of EPS with the pretreatment facilitate the biogas production at 702 L kg −1 VS, which was 3-folds of the control and significantly higher than other pretreatments. The result of excitation–emission matrix and parallel factor (EEM-PARAFAC) analysis showed that the SIC–H 2 O 2 pretreatment enhanced the dissociation of TB-EPS fractions, especially the protein-like and soluble microbial by-product-like substances. Electron paramagnetic resonance (EPR) results provided evidence for homolytic catalysis H 2 O 2 for the generation OH and the production of high-valent (Por)Fe IV (O) intermediates. Synergistic effects of reactive oxygen species ( OH, H 2 O 2 and /HO 2 ) and (Por)Fe IV (O) enhanced the EPS disintegration during SIC–H 2 O 2 pretreatment. The mixed-acid type fermentation provided continuous VFAs supply under the enrichment of Chloroflexi and Actinobacteria and multiplication Methanosaeta also promoted methane production. This research provides a feasible pretreatment strategy increase sludge biodegradability and enhance biogas production in the anaerobic digestion process.