Mathematical modelling of anaerobic digestion processes: applications and future needs

The Influence of Micro-Oxygen Addition on Desulfurization Performance and Microbial Communities during Waste-Activated Sludge Digestion in a Rusty Scrap Iron-Loaded Anaerobic Digester

“…On the 61st day (period P3), 1 mL pure O 2 was introduced into the reactor headspace, and as shown in Figure 2, the pH was maintained at ideal levels (6.8-7.2)., with similar effects observed at P4, P5 and P6. Supplying limited O 2 could have increased the chemical corrosion of ZVI, as the common consensus is that the principal site of cathodic oxygen reduction, (Equation (6)), and anodic metal dissolution according to Equation (7) occurs close to RSI edges [32]: When Fe(III) enters liquid phase it will rapidly be converted into Fe(II) by iron-reducing bacteria (IRB) [33,34]. By looking at the fast Fe(III) reduction at the time, two possible reasons could be proposed for the observed pH stabilization: (1) the electrons generated during the degradation of the sludge organics were, to a large extent, utilized for Fe(III) reduction, decreasing the amount of electrons flowing to the intermediates to form fermentation end products, mainly in the form of VFAs; (2) much of the resultant VFAs from the sludge digestion were consumed as the electron donors for Fe(III) reduction.…”

“…In comparison, in P7, excess oxygen disrupted the system reductive environment that is necessary for methanogens growth, followed by the reduction of average COD removal and average methane yield (Table 3). When Fe(III) enters liquid phase it will rapidly be converted into Fe(II) by iron-reducing bacteria (IRB) [33,34]. By looking at the fast Fe(III) reduction at the time, two possible reasons could be proposed for the observed pH stabilization: (1) the electrons generated during the degradation of the sludge organics were, to a large extent, utilized for Fe(III) reduction, decreasing the amount of electrons flowing to the intermediates to form fermentation end products, mainly in the form of VFAs; (2) much of the resultant VFAs from the sludge digestion were consumed as the electron donors for Fe(III) reduction.…”

“…These oxides are understood to react with H + (corrosion process), inducing the release of Fe(II) and Fe(III). When Fe(III) enters the liquid phase it is rapidly converted into Fe(II) by IRB [33,34]. Under anaerobic conditions, inner ZVI is oxidized to Fe(II), producing cathodic hydrogen (H2/[H]) via Equation (9) [41].…”

The Future Agricultural Biogas Plant in Germany: A Vision

“…The mostly used mechanistic model is the Anaerobic Digestion Model No. 1 (ADM 1) [60,61,63,64]. The ADM 1 as a dynamic model chiefly considers biochemical processes including the conversion of organic matter into carbohydrates, lipids, proteins and inert compounds as well as the four main process steps in terms of hydrolysis, acidogenesis, acetogenesis and methanogenesis including potential process inhibition by hydrogen and free ammonia [61].…”

Model‐based analysis and optimization of a full‐scale industrial high‐rate anaerobic bioreactor

“…1 (ADM1; Batstone, Keller, et al, 2002). Numerous studies presenting (mathematical) approaches describing new technologies, new processes, and the need to consider anaerobic systems in a much broader context of the wastewater cycle as a whole have been published in the specialized literature (Batstone, Puyol, Flores-Alsina, & Rodríguez, 2015). Within the area of new technologies, there is an increasing interest, particularly for industrial applications, to develop models for sludge bed systems containing biofilms, such as anaerobic contact processes, anaerobic filters, up-flow anaerobic sludge blanket reactors, fluidized bed reactors, expanded granular sludge bed reactors, and internal recirculation (IC) reactors (van Lier, van der Zee, Frijters, & Ersahin, 2015).…”