Environmental Engineering Reference
In-Depth Information
5.9
Conclusions and future trends
The bacterial processes involved in anaerobic digestion are understood, but
complex. The interplay of the complexity is best monitored using modelling
packages such as ADM1. Modelling will allow more aggressive loading of
reactor systems and lead to more economical design.
Continuously stirred reactors are ubiquitous; two-step systems are the
norm. Innovation has taken place in commercial reactors; this is particularly
the case for high solid content feedstocks that can now be digested in wet
digesters with recirculation of liquid digestate, sequentially fed dry batch
reactors with recirculation of liquor in a closed loop and dry continuous
reactors. However, the two-phase systems described in the scientific
literature (leach beds coupled with high rate digesters) are rarely
encountered in the commercial world. It is expected that these systems
will become more prevalent as the literature becomes more mainstream. It is
also the authors' opinion that the two-phase system will become associated
with green biorefinery systems.
Sustainability concepts that have been applied to liquid biofuel systems in
the EU Renewable Energy Directive (European Commission, 2009) will be
applied to bioenergy systems. The energy balance of the process will become
a more crucial design issue and may lead to the ultimate choice of reactor
system.
5.10 References
Archer D.B. and Kirsop B.H. (1990) The microbiology and control of anaerobic
digestion. In: Anaerobic Digestion: A Waste Treatment Technology. Critical
Reports on Applied Chemistry, Volume 31, edited by Andrew Wheatley.
Amsterdam: Elsevier.
Banks C. (2011) Matching AD requirements to different feedstocks: Understanding
the process and its requirements: a case study of food waste digestion in the UK.
Presented at International Energy Agency (IEA) Bioenergy Task 37, Tubitak
MRC, April 14 2011. Available from: http://www.iea-biogas.net/_download/
publications/workshop/8/3-MatchingAD_process.pdf
(accessed December
2011).
Batstone D.J., Keller J., Angelidaki I., Kalyuzhnyi S.V., Pavlostathis S.G., Rozzi A.,
Sanders W.T.M., Siegrist H. and Vavilin V.A. (2002) Anaerobic Digestion
Model No. 1. Scientific and Technical Report No. 13. IWA Task Group for
Mathematical Modelling of Anaerobic Digestion Processes. 77 p.
Buswell A.M. and Hatfield W.D. (1936) Bulletin No. 32, Anaerobic Fermentations.
State of Illinois, Department of Registration and Education, Division of the
State Water Survey, Urbana, Illinois. Available from: http://www.isws.illinois.
edu/pubdoc/B/ISWSB-32.pdf (accessed September 2012).
Casey T.J. (1981) Developments in Anaerobic Digestion. Lecture given to the Institute
of Engineers of Ireland, April and 1981.
Search WWH ::
Custom Search