Optimization of urban waste fermentation for volatile fatty acids production

Giulia Moretto; Francesco Valentino; Paolo Pavan; Mauro Majone; David Bolzonella

doi:10.1016/j.wasman.2019.05.010

Optimization of urban waste fermentation for volatile fatty acids production

Waste Manag. 2019 Jun 1:92:21-29. doi: 10.1016/j.wasman.2019.05.010. Epub 2019 May 9.

Authors

Giulia Moretto¹, Francesco Valentino², Paolo Pavan¹, Mauro Majone³, David Bolzonella⁴

Affiliations

¹ Department of Environmental Sciences, Informatics and Statistics, Ca' Foscari University of Venice, Dorsoduro 3246, 30123 Venice, Italy.
² Department of Chemistry, La Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy. Electronic address: francesco.valentino@uniroma1.it.
³ Department of Chemistry, La Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.
⁴ Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.

PMID: 31160023
DOI: 10.1016/j.wasman.2019.05.010

Abstract

The problem of waste disposal has recently focused on practices for waste recycling and bio-resources valorization. Organic waste produced in urban context together with biological sludge produced in wastewater treatment plants (WWTPs) can be used as renewable feedstock for the production of building blocks of different products, from biopolymers to methyl esters. This paper deals with the optimization of the fermentation process in order to transform urban organic waste (a mixture of pre-treated food waste and biological sludge) into added-value volatile fatty acid (VFA) rich stream, useful for biological processes within a biorefinery technology chain. Different temperatures, pH, hydraulic retention times (HRTs) and organic loading rates (OLRs) were tested both in batch and continuous trials. Batch tests showed the best working conditions at 37 °C and pH 9, using the bio-waste feedstock thermally pre-treated (76 h at 72 °C). These conditions were applied in continuous process, where higher HRT (6.0 d) and lower OLR [7.7 kg VS/(m³ d)] gave the best performances in terms of process yield and maximum VFA level achieved: 0.77 COD_VFA/VS₍₀₎ and 39 g COD_VFA/L. An optimized fermentation process is crucial in a biorefinery perspective since it has to give a final stream of constant composition or tailored products suitable for further applications.

Keywords: Anaerobic fermentation; Biorefinery; Organic fraction of municipal solid waste (OFMSW); Volatile Fatty Acid (VFA); Waste Activated Sludge (WAS).

MeSH terms

Bioreactors
Fatty Acids, Volatile*
Fermentation
Refuse Disposal*
Sewage
Wastewater

Substances

Fatty Acids, Volatile
Sewage
Waste Water