Extraction and characterization of the lipids from domestic sewage sludge and in situ synthesis of methyl esters

The solid waste from urban sewage treatment, such as the sludge that are removed from the drying beds and discharged of biological reactors, are products that need specific treatment, being considered great environmental polluters. These residues can be evaluated from the standpoint of revaluation and, considering the high concentration of lipids that are present in its composition, which can be converted in biodiesel. Thus, the objective of this study was to characterize and evaluate the production of esters by in situ transesterification utilizing the domestic sewage sludge as raw material. The collected sewage sludge presented 61% of organic matter and 39% of fixed solids, with 26% of neutral lipids of the material extracted. High value of the saponifiable material and free fatty acid contend, 22.1% and 97.77 mg KOH/g, respectively, were determined. The potential for biodiesel production was tested and 57.46 +/- 2.07 % (m/m) ester yield was obtained with predominance of the unsaturated methyl ester.