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73
Recognition of the dangers arising from pollution by sulphur
dioxide was evidenced as long ago as 1927, when, at the time of
the erection of the Battersea Power Station, the Electricity Commissioners
insisted that the evolution of this gas should, as far
as practicable, be prevented. This led to flue-gas scrubbing, i.e.
the flue gas was washed with river water to which had been added
an alkali to counteract acidity. Naturally, such a process is
limited to the actual physical amount of by-products which the
river can safely absorb. Other processes have been tried, some
of which, although technically sucessful, have proved uneconomical,
but the one most favoured at the moment is the Simon
Carves process, where the flue gases are scrubbed with a solution
of ammonium salts, which effectively removes the oxides of sulphur
and the resultant liquor yields ammonium sulphate and sulphur.
However, it suffers from the defect of all wet processes in that the
flue gas is cooled and saturated with water, which results in the discharge
at the chimney having little buoyancy with a poor dispersion
rate. What is required is a dry, regenerative process and
one, the German Reinluft process, is at present undergoing tests
at the Warren Spring Laboratories.
In this connection it is as well to remember that much of
the original work of the Department of Scientific and Industrial
Research on air pollution was carried out at Greenwich and that
the results obtained by this organisation were mainly responsible
for the introduction of the Clean Air Act.
Clean Air Act, 1956. Provisions relating to the installation of
new furnaces, smoke control areas, height of chimneys, research
and publicity, came into operation on the 31st December, 1956,
whilst the remaining provisions became effective on the 1st June,
1958.
The Act has, as its aim, four main purposes: —
1. To limit smoke from existing sources.
2. To prevent new sources of industrial smoke.
3. To minimise dust and grit emission.
4. For the first time in nationally applied legislation—to
bring about the progressive elimination of domestic
smoke.
In a recent survey carried out by the National Society for
Clean Air is was revealed that since 1956, industrial smoke has
been reduced by half and the amount of dust and grit by two
fifths. Such an improvement in the industrial field is