It is important to be aware that biotechnology is not the only answer to controlling air pollution. A number of alternative approaches exist, though it is clearly beyond the scope of this book to discuss them at length. The following brief outline may help to give a flavour of the wider context, but to understand how the various technologies compare, the reader should seek more detailed information.
Absorbing the compound in a suitable liquid; this may oxidise or neutralise it in the process.
Activated carbon preferentially adsorbs organic molecules; this can be tailored to give contaminant-specific optimum performance.
High temperature oxidation; effective against most contaminants, but costly.
Use of ozone to oxidise some contaminants, like hydrogen sulphide; effective but can be costly.
The main advantages of biotechnological approaches to the issue of air contam-ination can be summarised as:
· competitive capital costs;
· low running costs;
· low maintenance costs;
· low noise;
· no carbon monoxide production;
· avoids high temperature requirement or explosion risk;
· safe processes with highly ‘green’ profile;
· robust and tolerant of fluctuation.
As was discussed, pollution control stands as one of the three major intervention points for the application of environmental biotechnology. Having defined some of the major principles and issues. However, it must not be forgotten that, as with all tripods, each leg is equally important; the potential contribution to be made by the so-called ‘clean technologies’ in manufacturing should not be overlooked. Much of the focus of environmental biotechnology centres on the remediation of pollution or the treatment of waste products. In many respects, this tends to form the natural constituency of the science and is, certainly, where the bulk of practical applications have generally occurred. While the benefits of the controlled biodegradation of unwanted wastes or contaminants is clear, this does typify ‘end-of-pipe’ thinking and has led, to some extent justifiably, to the criticism that it merely represents moving the problem from one place to another. Another option to deal with both these ongoing problems is, simply, to avoid their production in the first place and while this may seem over-idealistic in some aspects, it does have a clear and logical appeal. Throughout this book, ‘environmental’ biotechnology is defined in the broad sense of the utilisation of applied biological methods to the benefit of the environment. Thus, any use of the life sciences which removes, remediates or obviates contamination of the biosphere falls firmly within its remit and a priori action, to avoid the problem in the first place must be preferential. The proverbial ounce of prevention is worth a pound of cure.
The current emphasis on clean-up and treatment is largely the result of his-torical circumstance. As legislation has become more stringent, the regulation of waste and pollution has correspondingly forced the pace of environmental inter-vention. In addition, the prevalence of ‘the polluter pays’ principle, coupled with ever greater pressures to redevelop existing ‘brown-field’ sites, in preference to de novo development has inevitably necessitated a somewhat reactive response.However, increasingly biotechnologies are being developed which, though per-haps not ‘environmental’ in themselves, bring significant benefits to this sphere. Their advantages to industry in terms of reduced demands for integrated pollution control and minimised waste disposal costs also suggest a clear likelihood of their success in the commercial sphere. Generally, the environment has tended to fare best when its interests and economic ones go hand in hand and the pre-emptive approach which the new technologies herald seems ideally suited to both.
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