Environmental Engineering Reference
In-Depth Information
10.4.2 Anaerobic digestion modelling developments and
trends
The IWA Anaerobic Digestion Modelling Task Group constructed a
generalised AD model (Batstone et al., 2002) called ADM1 (previously
discussed in Chapter 5). The group foresaw many benefits for the
development of a generic model that could be related to practical or
industrial applications, such as
application for full-scale plant design, operation and optimisation
.
process optimisation and control
.
.
a common basis for model development and validation to make
outcomes more comparable and compatible
.
assistance for technology transfer from research to industry.
The ultimate goal was to support the increasing application of the AD
process as a sustainable way to treat wastes and produce renewable energy
(Batstone et al., 2002). ADM1 includes disintegration, hydrolysis, acid-
ogenesis and methanogenesis. In total, it accounts for 19 biochemical
reactions associated with 7 bacterial populations. The kinetics is structured
according to a Monod function of the substrate and takes into consideration
pH, hydrogen and ammonia inhibition terms. Moreover, the model also
accounts for physico-chemical reactions: liquid-gas transfer, acid-base
reactions and pH (Batstone et al., 2002). The model was tested in several
different scenarios (Parker, 2005) where a number of data sets were
examined. It is a very powerful tool when the feed stream is well
characterised by COD content and the biodegradable fractions. Attempts
for validation against pilot plant experiments (Blumensaat and Keller, 2005)
were also carried out. Blumensaat and Keller (2005) stated that several
updates had to be implemented to fit the existing models to pilot-scale
performances. Another example of the model extension was presented by
Fezzani and Cheikh (2009) who attempted to include the degradation of
phenols. Concerning mono-digestion systems, Koch et al. (2010) and
Thamsiriroj and Murphy (2011) modelled grass silage digestion and both
groups found good agreement of the model with measured data. The first
study was focused on a description of nitrogen incorporation and release to
predict the nitrogen ammonia curve, whereas the second study aimed for
recommendation of the process configuration and the level of liquor
recirculation. Mairet et al. (2011), on the other hand, performed work on
modelling the anaerobic digestion of microalgae, one of the new promising
sustainable raw materials for biofuels production. A dynamic model of
microalgae-based AD could help understand the complexity of the process
and identify possible optimal solutions.
Different models have addressed a number of aspects crucial
for
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