Efficient solvent-less separation of lipids from municipal wet sewage scum and their sustainable conversion into biodiesel

Luigi di Bitonto, Antonio Lopez, Giuseppe Mascolo, Giuseppe Mininni and Carlo Pastore

Renewable Energy, 2016, vol. 90, issue C, 55-61

Abstract: A very efficient separation of lipids from wet sewage scum was optimised and positively tested on samples taken from several wastewater treatment plants (WWTPs). By simply heating sewage scum at 353 K and centrifuging the heated mass at 4000 rpm per 1 min, a recoverability of 93–99% of total oils was always obtained. This procedure resulted to be effective on samples with very different starting water contents. In all cases, extracted lipids have a very similar composition in terms of free fatty acids (FFAs), calcium soaps (32–40%wt) and glycerides (mono-, di- and tri-glycerides were practically absents), as well as fatty acid profiles. Once separated, lipids were converted into biodiesel through a direct esterification process carried out by adopting three sequential batch reactors, in which methanol and catalysts were charged in counter current. In this way, the complete conversion (>99%) of starting FFAs into FAMEs was perfectly matched with using the minimum amount of reactants under very mild conditions (345 K, 2 h). The overall convenience of the process was completed by the anaerobic digestion of fibrous residues obtained from centrifugation of starting sewage scum: the final biogas resulted largely enough to sustain the heat of process.

Keywords: Sewage scum; Biodiesel; Centrifugation; Direct esterification; FAMEs (search for similar items in EconPapers)
Date: 2016
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Citations: View citations in EconPapers (4)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:90:y:2016:i:c:p:55-61

DOI: 10.1016/j.renene.2015.12.049

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