Life Cycle Assessment of a system for the extraction and transformation of Waste Water Treatment Sludge (WWTS)-derived lipids into biodiesel

B Notarnicola; G Tassielli; P A Renzulli; R Di Capua; F Astuto; S Riela; A Nacci; M Casiello; M L Testa; L F Liotta; C Pastore

doi:10.1016/j.scitotenv.2023.163637

Life Cycle Assessment of a system for the extraction and transformation of Waste Water Treatment Sludge (WWTS)-derived lipids into biodiesel

Sci Total Environ. 2023 Jul 20:883:163637. doi: 10.1016/j.scitotenv.2023.163637. Epub 2023 Apr 23.

Authors

B Notarnicola¹, G Tassielli¹, P A Renzulli¹, R Di Capua², F Astuto¹, S Riela³, A Nacci⁴, M Casiello⁴, M L Testa⁵, L F Liotta⁵, C Pastore⁶

Affiliations

¹ Ionian Department of Law, Economics and Environment, University of Bari Aldo Moro, Taranto, Italy.
² Ionian Department of Law, Economics and Environment, University of Bari Aldo Moro, Taranto, Italy. Electronic address: rosa.dicapua@uniba.it.
³ Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), V.le delle Scienze, Ed. 17, 90128 Palermo, Italy.
⁴ Chemistry Department, University of Bari Aldo Moro, Bari, Italy.
⁵ CNR - Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN), Palermo, Italy.
⁶ CNR - Istituto di Ricerca Sulle Acque (CNR-IRSA), Bari, Italy.

PMID: 37098396
DOI: 10.1016/j.scitotenv.2023.163637

Abstract

In recent years, the demand for biofuels has been growing exponentially, as has the interest in biodiesel produced from organic matrices. Particularly interesting, due to its economic and environmental advantages, is the use of the lipids present in sewage sludge as a raw material for the synthesis of biodiesel. The possible processes of this biodiesel synthesis, starting from lipid matter, are represented by the conventional process with sulfuric acid, by the process with aluminium chloride hexahydrate and by processes that use solid catalysts such as those consisting of mixed metal oxides, functionalized halloysites, mesoporous perovskite and functionalized silicas. In literature there are numerous Life Cycle Assessment (LCA) studies concerning biodiesel production systems, but not many studies consider processes that start from sewage sludge and that use solid catalysts. In addition, no LCA studies were reported on solid acid catalysts nor on those based on mixed metal oxides which present some precious advantages, over the homogeneous analogous ones, such as higher recyclability, prevention of foams and corrosion phenomena, and an easier separation and purification of biodiesel product. This research work reports the results of a comparative LCA study applied to a system that uses a solvent free pilot plant for the extraction and transformation of lipids from sewage sludge via seven different scenarios that differ in the type of catalyst used. The biodiesel synthesis scenario using aluminium chloride hexahydrate as catalyst has the best environmental profile. Biodiesel synthesis scenarios using solid catalysts are worse due to higher methanol consumption which requires higher electricity consumption. The worst scenario is the one using functionalized halloysites. Further future developments of the research require the passage from the pilot scale to the industrial scale in order to obtain environmental results to be used for a more reliable comparison with the literature data.

Keywords: Aluminium chloride hexahydrate; Biodiesel production; Life Cycle Assessment; Solid catalysts; Sulfuric acid.