Fabrication of heterogeneous catalyst for production of biodiesel form municipal sludge

Sewage sludge, a semi-solid byproducts of municipal wastewater treatment processes, offers a sustainable and cost-effective feedstock for biodiesel production through the synthesis of catalytic heterogeneous catalysts. In this study, we developed a novel heterogeneous catalyst by impregnating aluminum nitrate and calcite, obtained from carbon dioxide-sequestering bacteria, onto DigSBiochar (Biochar derived from digested sewage sludge). The produced catalyst was subsequently immobilized with the lipase enzyme isolated from Bacillus sp., creating a bioactive material for the transesterification of lipids in sewage sludge. Comprehensive characterization of the biocatalysts was conducted using Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), and Field Emission Scanning Electron Microscopy (FE-SEM). Gas Chromatography-Mass Spectrometry (GC-MS) analysis of the resulting fatty acid methyl esters (FAMEs) demonstrated that the highest yield was achieved with the enzyme immobilized on the activated heterogeneous catalyst using methanol (99 %), followed by the activated heterogeneous catalyst with methanol (96 %), and methanol with Sulfuric acid (82 %). This study underscores the potential of utilizing municipal sewage sludge as a valuable resource for producing efficient heterogeneous catalysts, thereby advancing sustainable waste management practices and promoting renewable energy production. © 2024 The Institution of Chemical Engineers