title: Anaerobic co-digestion: A critical review of mathematical modelling for performance optimization.
abstract: Anaerobic co-digestion (AcoD) is a pragmatic approach to simultaneously manage organic wastes and produce renewable energy. This review demonstrates the need for improving AcoD modelling capacities to simulate the complex physicochemical and biochemical processes. Compared to mono-digestion, AcoD is more susceptible to process instability, as it operates at a higher organic loading and significant variation in substrate composition. Data corroborated here reveal that it is essential to model the transient variation in pH and inhibitory intermediates (e.g. ammonia and organic acids) for AcoD optimization. Mechanistic models (based on the ADM1 framework) have become the norm for AcoD modelling. However, key features in current AcoD models, especially relationships between system performance and co-substrates' properties, organic loading, and inhibition mechanisms, remain underdeveloped. It is also necessary to predict biogas quantity and composition as well as biosolids quality by considering the conversion and distribution of sulfur, phosphorus, and nitrogen during AcoD.
authors.affiliation: Strategic Water Infrastructure Laboratory, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Sihuang
authors.initials: S
authors.lastname: Xie
authors.affiliation: Strategic Water Infrastructure Laboratory, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: Faisal I
authors.initials: FI
authors.lastname: Hai
authors.affiliation: Civil Engineering, College of Engineering and Informatics, National University of Ireland, Galway, Ireland.
authors.forename: Xinmin
authors.initials: X
authors.lastname: Zhan
authors.affiliation: Centre for Technologies in Water and Wastewater, University of Technology Sydney, Sydney, NSW 2007, Australia.
authors.forename: Wenshan
authors.initials: W
authors.lastname: Guo
authors.affiliation: Centre for Technologies in Water and Wastewater, University of Technology Sydney, Sydney, NSW 2007, Australia.
authors.forename: Hao H
authors.initials: HH
authors.lastname: Ngo
authors.affiliation: Strategic Water Infrastructure Laboratory, University of Wollongong, Wollongong, NSW 2522, Australia.
authors.forename: William E
authors.initials: WE
authors.lastname: Price
authors.affiliation: Strategic Water Infrastructure Laboratory, University of Wollongong, Wollongong, NSW 2522, Australia. Electronic address: longn@uow.edu.au.
authors.forename: Long D
authors.initials: LD
authors.lastname: Nghiem
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D006863:Hydrogen-Ion Concentration; D059013:Microbial Consortia / Q000502:physiology; D008962:Models, Theoretical; D009584:Nitrogen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D012722:Sewage / Q000737:chemistry; D013455:Sulfur / Q000378:metabolism; D018505:Waste Management / Q000379:methods*
chemical_list: D056804:Biofuels; D012722:Sewage; D010758:Phosphorus; D013455:Sulfur; D009584:Nitrogen
keywords: Anaerobic co-digestion; Biosolids quality; Mathematical modelling; Nutrient recovery; Process stability; Sewage sludge