Multi-Stage Plastic Media Treatment Plants
PHILLIP N. J. CHIPPERFIELD, Scientific Advisor
M. W. ASKEW, Senior Project Officer
Imperial Chemical Industries, Ltd.
Paints Division, Freshwater Quarry
Devon, England
J. H. BENTON, Product Manager
Ethyl Corporation
Baton Rouge. Louisiana
INTRODUCTION
During the past few years, high rate treatment of domestic sewage and, in
particular, biodegradable industrial wastes on biological filters packed with scientifically designed fabricated plastic media has become recognized on both sides of the
Atlantic us an effective and efficient alternative to conventional methods of
biological treatment, namely, filters randomly packed with crushed stone, etc., and
activated sludge. There are now many references in the literature to research and
pilot studies of them, to their application in full scale plants, and to the basic
principles underlying their use and mode of operation (1,2,3,4,5,6,7,8,9).
Most of the papers relating to pilot studies and full scale installations
(particularly in the USA) have described plants in which a single stage of plastic
packed filter only is employed to produce an effluent of desired quality for final
discharge (10,11,12), or alternatively as a first or "roughing" stage of a two-stage
design in which the second stage is a conventional filter or activated sludge unit, to
produce an effluent of quality sufficiently high for direct discharge to a natural water
- e.g. Royal Commision standard (2,3,10).
However, unlike practice thus far established in the USA, multi-stage treatment
plants consisting of two, three or even four stages of plastic packed filters operating in
series and treating industrial wastes are not common in the UK: in general, the three
and four stage ones have been designed to produce a final effluent of the desired
quality for discharge direct to a natural water or to a public sewer for final treatment
on a municipal plant, or followed by conventional treatment units to produce
effluents of Royal Commission or better quality for direct discharge to rivers and
streams. In fact, out of some 90 plants based upon one particular British plastic
packing at present operating or under construction, 18 are multi-stage.
In the present paper the design and operation of a selection of the more
significant of these, treating a variety of industrial wastes, are described, together
with brief mention of one or two multi-stage pilot plants of interest: the technical
and economic advantages of multi-stage operation over simpler single-stage systems
to produce the same effluent quality are discussed.
TRLATMINT OF WHISKY DISTILLING EFFLUENTS
Malt whisky, on the content of which depends to a large extent the quality of
blended Scotch whisky, is produced in comparatively small quantities in individual
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