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8. NOXIOUS EFFLUVIA. The proximity of industrial
development to residential areas in Wembley has, during the year,
occasioned several complaints of unpleasant odours emanating from
factories to the disturbance and annoyance of residents. Where the
noxious smell arises as a consequence of some industrial process,
such as in engineering works, it is comparatively easy to make
arrangements for the offending air, which is usually extracted by some
ventilating system, to be discharged to the open air at such an
altitude or situation as to minimise complaint by residents. Where
the actual material manufactured emits an odour during the process
of manufacture, then the size of the particulate cloud is consequently
increased and difficulties in dealing with this type of offence are
magnified proportionately. Very detailed investigations of methods
of dealing with such effluvia have been undertaken in Wembley.
There are many basic methods of dealing with the impregnated
air, but in industrial application the following are most important.
If it is possible to extract the odoriferous fumes and inject these
into a furnace, when the suspended material which causes the odour
will be burnt and probably completely oxidised to an inert particle
or gas.
Another method, successful where the particulate concentration
is large, involves the passing of the extracted air over an oxy-catalyst
which by chemical reaction oxidises the material causing the smell,
burning this away, and by this combustion, maintains a temperature
which in turn oxidises the next approaching contaminated air stream.
It is known that some smells will counteract others and there are
firms who specialise in the balancing of odours in such a way that no
sensation is appreciable to the human sense of smell. This is an
extremely abstruse and secret field of work but on occasions where
industrial smells have been very offensive success has been achieved
by reducing the intensity of the odour below the threshold of
complaint.
A natural method is to extract the air contaminated with
odoriferous particles and discharge this via a duct at high altitude,
when dispersal and oxidation of the particulate content will occur
before the gases return to ground level.
The use of scrubbers, ultra violet ray, oxidising agents or
absorption, also finds application in the industrial field.
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