Overcoming ammonia inhibition via biochar-assisted anaerobic co-digestion of thermally-treated thickened waste activated sludge and food waste

Basem Haroun; Mohamed El-Qelish; Mariam Abdulazeez; Ahmed Khalil; Mingu Kim; George Nakhla

doi:10.1016/j.jenvman.2024.123909

Overcoming ammonia inhibition via biochar-assisted anaerobic co-digestion of thermally-treated thickened waste activated sludge and food waste

J Environ Manage. 2025 Jan:373:123909. doi: 10.1016/j.jenvman.2024.123909. Epub 2024 Dec 29.

Authors

Basem Haroun¹, Mohamed El-Qelish², Mariam Abdulazeez³, Ahmed Khalil⁴, Mingu Kim⁵, George Nakhla⁶

Affiliations

¹ Chemical and Biochemical Engineering Department, University of Western Ontario, London, ON, N6A 5B9, Canada. Electronic address: [email protected].
² Chemical and Biochemical Engineering Department, University of Western Ontario, London, ON, N6A 5B9, Canada; Water Pollution Research Department, National Research Centre, El Buhouth St., Dokki, 12622 Cairo, Egypt. Electronic address: [email protected].
³ Civil and Environmental Engineering Department, University of Western Ontario, London, ON, N6A 5B9, Canada. Electronic address: [email protected].
⁴ Mechanical and Material Engineering Department, University of Western Ontario, London, ON, N6A 5B9, Canada. Electronic address: [email protected].
⁵ Chemical and Biochemical Engineering Department, University of Western Ontario, London, ON, N6A 5B9, Canada; Lambton College, Sarnia, ON, Canada. Electronic address: [email protected].
⁶ Chemical and Biochemical Engineering Department, University of Western Ontario, London, ON, N6A 5B9, Canada; Civil and Environmental Engineering Department, University of Western Ontario, London, ON, N6A 5B9, Canada. Electronic address: [email protected].

PMID: 39736230
DOI: 10.1016/j.jenvman.2024.123909

Abstract

The convergence of sustainability and climate change has catalyzed the pursuit of inventive strategies for waste management and sustainable energy production. Hereby, we explored the effect of coupling biochar addition and thermal pretreatment in anaerobic mono-digestion and co-digestion of thermally pretreated thickened waste activated sludge (PTWAS) with food waste (FW). Six semi-continuous lab-scale digesters were operated for 161 days at various organic loading rates (OLR of 2, 3, 4 and 8 kgCOD/m³/day) with and without biochar (BC) addition. Coupling biochar addition and co-digestion of 30%FW +70% PTWAS, increased methane yield (MY) by 87.5% to 0.15 LCH₄/gCOD added, when the systems experienced high ammonia concentration of 2.4 g/L at OLR of 8 kgCOD/m³/d. The non-competitive ammonia inhibition constant (Ki) ranged from 0.250 g/L to 0.345 g/L. The maximum COD-to-BC ratio to overcome inhibition was 16.5 g COD _substrate/g BC corresponding to TN-to-BC ratio of 0.84 g TN _substrate/g BC. These results imply that biochar addition to the anaerobic co-digestion of thermally pretreated TWAS and FW can promote high-rate anaerobic digestion by relieving ammonia and VFA inhibition.

Keywords: Anaerobic digestion; Biochar; Co-digestion; Food waste; Municipal sludge; Pre-treatment.

MeSH terms

Ammonia* / chemistry
Anaerobiosis
Bioreactors
Charcoal* / chemistry
Food
Food Loss and Waste
Methane / metabolism
Sewage*
Waste Disposal, Fluid / methods
Waste Management / methods

Substances

Ammonia
Sewage
Charcoal
biochar
Methane
Food Loss and Waste