Synergism of co-digestion of food wastes with municipal wastewater treatment biosolids

M Kim; M M I Chowdhury; G Nakhla; M Keleman

doi:10.1016/j.wasman.2016.10.010

Synergism of co-digestion of food wastes with municipal wastewater treatment biosolids

Waste Manag. 2017 Mar:61:473-483. doi: 10.1016/j.wasman.2016.10.010. Epub 2016 Oct 24.

Authors

M Kim¹, M M I Chowdhury², G Nakhla³, M Keleman⁴

Affiliations

¹ Chemical and Biochemical Engineering, The University of Western Ontario, London, ON N6A 5B9, Canada.
² Civil and Environmental Engineering, The University of Western Ontario, London, ON N6A 5B9, Canada.
³ Chemical and Biochemical Engineering, The University of Western Ontario, London, ON N6A 5B9, Canada; Civil and Environmental Engineering, The University of Western Ontario, London, ON N6A 5B9, Canada. Electronic address: gnakhla@uwo.ca.
⁴ InSinkErator, Emerson Commercial & Residential Solutions, 4700 21st Street, Racine, WI 53406-5031, United States.

PMID: 27789104
DOI: 10.1016/j.wasman.2016.10.010

Abstract

Five semi-continuous flow anaerobic digesters treating a mixture of food waste (FW) and municipal biosolids (primary sludge and thickened wasted activated sludge) at an solids retention time (SRT) of 20 days and different blend ratios i.e. 0, 10%, 20%, 40% by volume with the fifth digester treating only biosolids at the same COD/N ratio as the 40% FW digester were operated to investigate co-digestion performance. Sixty days of steady-state operation at organic loading rates (OLR) of 2.2-3.85kgCOD/m³/d showed that COD removals were higher for the three co-digesters than for the two municipal biosolids digesters i.e. 61-69% versus 47-52%. Specific methane production per influent CODs were 1.3-1.8 folds higher in co-digestion than mono-digestion. The first-order COD degradation kinetic constants for co-digestion were more than double the mono-digestion. Additional methane production through synergism accounted for a minimum of 18-20% of the overall methane production. The estimated non-biodegradable fraction of the FW particulate COD was 7.3%. However, the co-digesters discharged 1.23-1.64 times higher soluble nitrogen than the control.

Keywords: Anaerobic digestion; COD/N ratio; Co-digestion; Food wastes; Primary sludge; Thickened waste activated sludge.

MeSH terms

Anaerobiosis
Biofuels
Biological Oxygen Demand Analysis
Bioreactors / microbiology
Food*
Methane / biosynthesis
Microbial Consortia
Nitrogen / metabolism
Waste Disposal, Fluid / instrumentation
Waste Disposal, Fluid / methods*

Substances

Biofuels
Nitrogen
Methane