Biotechnology and Waste 175of sugars and therefore are carbohydrates, lignin is a polymer of the two amino
acids, phenylalanine and tyrosine. Despite its abundance, its structure is poorly
understood, in part a tribute to the fact that it is extremely resistant to degrada-
tion and therefore presents problems to the analyst. Fortunately for the natural
process of carbon and nitrogen recycling on which our biosphere depends, fungi
degrade lignin and, in addition, some microbes, like those resident in the gut of
termites can perform the same function.
Biowaste makes up a huge percentage of refuse; some 2500 million tonnes
arise each year in the European Union alone (Lemmes 1998) and this is a figure
which many authorities suggest increases by between 3–5% annually. Although
the focus of much of this chapter is firmly centred on the biowaste component of
municipal solid waste (MSW), since this is the kind of waste which most directly
concerns the largest number of people, it is important to be aware that this does
not represent the full picture, by any means. Of these 2500 million tonnes of
biowaste, 1000 million is agricultural in origin, 550 million tonnes consists of
garden and forestry waste, 500 million is sewage and 250 million results from
the food-processing industry, leaving MSW only to make up the remaining 200
million tonnes. The scale of the problem is large, one study suggesting that an
annual total of between 850–1000 kg (total solids) of material suitable for biolog-
ical treatment are produced per person (Frostell 1992). There is general agreement
that biowaste accounts for around a third of the industrialised world’s municipal
waste stream and that a further 30% or so is also expressly biodegradable, such
a definition including paper. In the light of this, the fact that the potential for
the development and application of approaches based on biological processing
has not yet been more rigorously or comprehensively explored remains some-
what surprising. Moreover, with society in general increasingly committed to the
‘green’ ideals of maximised recycling and the rational utilisation of waste, it
is difficult to see how such goals can realistically ever be expected to be met,
without significant attention being paid to the biowaste issue. In this respect, the
writing may already be on the wall, since the demands of legislation appearing in
Europe, the USA and elsewhere has begun to drive fundamental reappraisals of
the way in which all refuse is regarded. In particular, regulatory changes designed
to reduce the amount of raw biodegradable material destined for landfill must
ultimately come to promote biotechnologies which can treat this material in an
effective and more environmentally acceptable way. While predicting the future
is, of course, notoriously difficult, it seems likely that biological processing will
assume a more central role in future waste management regimes, which presents
both exciting possibilities and some genuine challenges to the industry itself.
However, in order to understand why, it is important to consider the current
difficulties posed by biowaste under traditional disposal routes.
Although a number of changes in the whole perception of waste have led to
a variety of relatively new options receiving attention, generally throughout the
world, the vast majority of refuse is dealt with either by means of landfill or