Biomedical Engineering Reference
In-Depth Information
approaches demands a sizable and sustainable outlet. Suffice it to say that any
such marketing operation requires significant assurances to the customer in
terms of the material's quality, safety and value and moves are afoot to establish
more widely agreed and accepted criteria. To this end, developments like the
application of SOUR testing as a means of objectively assessing microbial
activity within the composting matrix may have a wider role to play.
Another area of concern often expressed is that of pathogen persistence, which
leads many to view the need for sanitisation as synonymous with sterilisation,
which, of course, it is not. The health risks potentially associated with biowaste
processing to both workers and end-users has been well documented elsewhere
and it is not our intention to restate that work here. However, what is less
widely appreciated, and is more directly relevant to our central theme, is that
particularly for large scale applications a balanced and thriving community of
micro-organisms is one of the most valuable contributions a good biowaste-
derived soil amendment can make to poor soils. Removing pathogens, weed
seeds and spores from biologically processed waste while not producing a sterile
wasteland remains one of the key balancing acts of biowaste treatment.
Ironically, it is the expansion of biotechnology in areas beyond the develop-
ment of better systems for immediate biowaste treatment which is likely to have
major implications for waste management. For any processing technology, there
is clear advantage in having a relatively pure input material and this has led to
much discussion over the years regarding the respective benefits of separation on
site against householder segregation. The latter approach has itself led to the plas-
tic bags in which the biowaste so segregated becoming something of a nuisance
at central treatment facilities, typically needing to be opened and removed, which
is a labour intensive operation at such a large scale. The increasing use of truly
biodegradable plastics has already started to have an impact on the situation,
especially at composting plants, since bags which will themselves decompose
significantly reduce the amount of work involved.
If the predicted widespread use of cheap bio-plastics, grown as alternative
crops in transgenic plants, becomes a reality in the future, then this may itself
have repercussions for the amount of material requiring biological treatment.
Plastics account for around 8-10% of the developed world's waste stream and,
while reducing the demand for finite oil resources for the production of polymers
has much to recommend it, one inevitable consequence will be to increase the
amount of expressly biodegradable material in refuse. With growing numbers
of countries looking to increase biowaste diversion, even allowing for effec-
tive recycling initiatives and attempts at waste minimisation, biotechnology may
play an even larger part in the approaches to integrated waste management of
the future.
The role of such integrated technologies in dealing with waste while simul-
taneously allowing components, either material or energy, to re-enter the chain
of commercial utility will continue to prove a vital one. In whatever form this
most fundamental of recycling is achieved, an adequate final market is essential.
Whether the end product is fundamentally reclaimed humus and minerals or a
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