Environmental Engineering Reference
In-Depth Information
Overall, the anaerobic digestion process may contribute significantly to the sus-
tainable energy supply of the future. However, at the current price levels for natural
gas, bioenergy production as driver for development of the anaerobic digestion proc-
ess will only be of limited value compared to waste stabilization and reuse-related
objectives of the process.
CHAPTER SUMMARY AND STUDY GUIDE
This chapter describes the anaerobic digestion process for production of methane-
containing biogas from various feedstocks. The biochemical and thermodynamic
bases of the process are described, and some basic tools for feedstock characterization
and estimation of the biogas potential of a substrate are described. Fundamental
bioprocess engineering considerations that enable bioreactor design are presented.
Integration of the process in a treatment scheme including nutrient recovery, heat
integration, and electricity production is described.
KEY CONCEPTS
Anaerobic digestion
Methane-containing biogas
Natural gas
Degradation pathway
Cell growth and maintenance
Process thermodynamics
Carbohydrates, proteins, and lipids
Nutrient recovery
Process integration
SHORT-ANSWER QUESTIONS
14.1 Reproduce the elemental composition of the feedstocks shown in Table 14.3
from the basic ODM, COD, and organic N measurements.
14.2 Estimate the feedstock composition in terms of the fraction lipids, proteins,
and carbohydrates.
14.3 Reproduce the potential biogas production (L.kg −1 ) and the biogas composi-
tion (vol.% CH 4 ) of the feedstocks shown in Table 14.3.
14.4 Why do you think the biodegradable fraction of pig manure is low compared to
that of the other feedstocks?
14.5 Why is the end product of anaerobic digestion methane-containing biogas and
not, e.g., ethanol?
 
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