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London County Council.
FILTRATION OF CRUDE SEWAGE.
Report by the Chemist on the Bacteriological Examination of London Crude Sewage
as it is delivered at the Barking and Crossness Outfall works.
(Printed, by order of the Main Drainage Committee, 16th June, 1898.)
First Report.
To the Main Drainage Committee.
The Committee will remember that on the 8th of February last the Council sanctioned the
appointment of Dr. Houston, as a bacteriologist, to co-operate with me in the experimental treatment of
the crude sewage at Crossness by filtration through coke. Pending the construction and maturing of
the filter, Dr. Houston has made a study of the bacteriology of the crude sewage, the results of which
are summarised in the following report. The information herein contained is preliminary to a
bacteriological study of the filter itself and of " the filtrates," or filtered sewage which is discharged as
an effluent from the coke filter. The filter has now been in action for about seven weeks, and, as the
Committee will have gathered from my periodical chemical reports, is rapidly "maturing," or arriving
at a condition when it furnishes its best results. The bacteriological study of the raw sewage is
therefore now being followed by the study of the filter and filtrate, and the results thus obtained will be
reported in due course.
It is believed that the information and the original photomicrographic illustrations which appear
in the present report will be of considerable permanent value to the Council's staff at the Outfalls and
to many others who are not immediately connected with the Council.

A.—INTRODUCTION.
From the end of February to the date of preparing this report (May 9th, 1898), the bacteriological
work has consisted in the examination of samples of London crude sewage, obtained from the
outfall works at Barking and Crossness. During this time the new filter beds at Barking and
Crossness were only in course of construction. They have since been completed and are now being
fed with the sewage.
There was an advantage in this unavoidable delay, as it was important to gain as accurate a
knowledge as possible of the number and kind of bacteria which were present in the raw sewage; and
this knowledge should naturally be obtained before the study of the changes brought about by microorganisms
in filter beds, specially designed to effect the biological purification of sewage, was
commenced.
This report, however, is only to be regarded as a preliminary statement of the progress of the
work. It would be quite impossible to adequately deal with the bacteriology of sewage as the result
of a few months' work. The study of the bacteria in London crude sewage is still receiving close
attention, and it will be necessary in the future to carry on a series of comparative experiments with
the effluents from the filter beds.
* The work was done in the Public Health Laboratory, St. Bartholomew's Hospital. I desire to record my
thanks to Dr. Klein for advice and help of the greatest value.—A. C. H.