Boosting biogas production from sewage sludge by adding small amount of agro-industrial by-products and food waste residues

A E Maragkaki; M Fountoulakis; A Kyriakou; K Lasaridi; T Manios

doi:10.1016/j.wasman.2017.04.024

Boosting biogas production from sewage sludge by adding small amount of agro-industrial by-products and food waste residues

Waste Manag. 2018 Jan:71:605-611. doi: 10.1016/j.wasman.2017.04.024. Epub 2017 Apr 17.

Authors

A E Maragkaki¹, M Fountoulakis², A Kyriakou³, K Lasaridi³, T Manios²

Affiliations

¹ Laboratory of Natural Resources, Management & Agricultural Engineering, Department of Agriculture, Technological Educational Institute of Crete, Heraklion 71410, Crete, Greece; Harokopio University, Department of Geography, 70 El. Venizelou St., 176 71 Kallithea, Athens, Greece. Electronic address: amaragkaki@staff.teicrete.gr.
² Laboratory of Natural Resources, Management & Agricultural Engineering, Department of Agriculture, Technological Educational Institute of Crete, Heraklion 71410, Crete, Greece.
³ Harokopio University, Department of Geography, 70 El. Venizelou St., 176 71 Kallithea, Athens, Greece.

PMID: 28427739
DOI: 10.1016/j.wasman.2017.04.024

Abstract

In Greece, in many cities, wastewater treatment plants (WWTPs) operate their own anaerobic digestion (AD) facility in order to treat sewage sludge rather than achieve optimum biogas production. Nowadays, there is a growing interest regarding the addition of other co-substrates in these existing facilities in order to increase gas yield from the biomass. This practice may be possible by adding small amount of co-substrates which will not affect significantly in the designed hydraulic retention time. Nonetheless, the lack of experimental data regarding this option is a serious obstacle. In this study, the effect of co-digestion sewage sludge, with small amount of agro-industrial by-products and food wastes is examined in lab-scale experiments. Specifically, co-digestion of SS and food waste (FW), grape residues (GR), crude glycerol (CG), cheese whey (CW) and sheep manure (SM), in a small ratio of 5-10% (v/v) was investigated. The effect of agro-industrial by-products and food waste residues on biogas production was investigated using one 1L and three 3L lab-scale reactors under mesophilic conditions at a 24-day hydraulic retention time. The biogas production rate reached 223, 259, 406, 572, 682 and 1751 mlbiogas/lreactor/d for 100% SS, 5% SM & 95% SS, 10% CW & 90% SS, 5% FW & 95% SS, 5% FW & 5% CG & 90% SS and 5% CG & 95% SS respectively. Depending on the co-digestion material, the average removal of total chemical oxygen demand (TCOD) ranged between 20% (5% SM & 95% SS) and 76% (5% FW & 5% CG & 90% SS). Reduction in the volatile solids ranged between 26% (5% SM & 95% SS) and 62% (5% FW & 5% CG & 90% SS) for organic loading rates between 0.8kgVSm^-3d^-1 and 2.0kgVSm^-3d^-1. Moreover, co-digestion improved biogas production from 14% (5% SM & 95% SS) to 674% (5% CG & 95% SS). This work suggests that WWTPs in Greece can increase biogas production by adding other wastes to the sewage sludge without affecting the operation of existing digesters and without requiring additional facilities.

Keywords: Agro-industrial by-products; Anaerobic co-digestion; Bio-energy; Food waste; Methane; Wastewater treatment plants.

MeSH terms

Anaerobiosis
Animals
Biofuels*
Bioreactors
Greece
Methane
Sewage*

Substances

Biofuels
Sewage
Methane