Hydrothermal Carbonization of Dry Anaerobic Digestion Residues Derived from Food and Agro Wastes in Lesvos Island

Panagiotis Xypolias, Stergios Vakalis (), Ioannis Daskaloudis and Dimitrios Francis Lekkas ()
Additional contact information
Panagiotis Xypolias: Waste Management Laboratory, Department of Environment, University of the Aegean, University Hill, 81100 Mytilene, Greece
Stergios Vakalis: Energy Management Laboratory, Department of Environment, University of the Aegean, University Hill, 81100 Mytilene, Greece
Ioannis Daskaloudis: Waste Management Laboratory, Department of Environment, University of the Aegean, University Hill, 81100 Mytilene, Greece
Dimitrios Francis Lekkas: Waste Management Laboratory, Department of Environment, University of the Aegean, University Hill, 81100 Mytilene, Greece

Energies, 2023, vol. 16, issue 12, 1-14

Abstract: Biowaste management is at the center of attention in recent years due to the increased focus on Circular Economy practices. Lesvos has numerous food processing facilities and olive mills, and therefore Olive Mill Wastewater (OMWW) is a wastewater stream that requires attention. In this study, a holistic experimental set-up that combines aerobic and anaerobic treatment strategies was developed taking into consideration the hydrothermal carbonization of AD digestate along with locally available OMWW. The study focuses on the hydrothermal carbonization (HTC) of anaerobic residues from biogas production, and food waste was co-utilized with spent coffee grounds (SCG). The reduced volatile solids of SCG have some effects on the final products. AD produced methane yields of 54.7% for the food waste and 52.4%. for the feedstock with added SCG. At the same time, the feedstock that contained SCG produced more hydrochar that reached up to 50% of the yield. Hydrothermal carbonization in a water medium produced liquids with basic pH values around 8 and conductivities of 4–5 mS/cm, while the samples that were treated in OMWW medium had pH values close to 5.5 and conductivities of around 12 mS/cm. The produced hydrochars have significant calorific values that exceeded 20 MJ/kg for almost all the samples. Overall, HTC with OMWW as a medium was able significantly reduce the COD of OMWW while resulting in hydrochars with increased heating values.

Keywords: food waste; hydrothermal carbonization; hydrochar; biowaste; anaerobic digestion (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/1996-1073/16/12/4619/pdf (application/pdf)
https://www.mdpi.com/1996-1073/16/12/4619/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:16:y:2023:i:12:p:4619-:d:1167945

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().