Environmental Engineering Reference
In-Depth Information
2.2 Separate collection of digestible organic wastes is integrated in
overall waste management.
application of digestate from mixed-waste collection onto agricultural land
is not allowed in some countries.
Organic household wastes have a high biodegradability and methane
yield. Their nutrient content is well balanced and favorable for the
metabolism of anaerobic microorganisms (Zhang et al., 2006). As household
waste contains various pathogens, fungi and other biological vectors,
sanitation is required for effective inactivation of the pathogenic matter.
The main limitation of separate collection of organic household waste as
feedstock for AD is considered to be the apparently high cost of waste
collection. Favoino (2002) indicates that, in fact, the costs of separate
collection are comparable with traditional mixed-waste collection in cases
when the performances of the collection schemes are optimized and if
separate collection is an integrated part of the whole waste management
system. Furthermore, a significant income of many biogas plants running on
waste materials comes from gate (tipping) fees. Purity is another limiting
factor in the utilization of source-separated organic waste as a feedstock for
biogas production. The content of foreign materials depends to a very large
extent on the human factor (Favoino, 2002), that is, the awareness and
motivation of the population involved in collection systems. Favoino (2002)
indicates that, even if purities higher than 90% are achieved, organic
household wastes can contain significant amounts of disturbing compounds
such as metal, glass, plastic and sand. In most wet digestion processes, these
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