Recent improvements in methods for the biological purification of sewage / by W.J. Dibdin.

  • William Joseph Dibdin
Date:
1907
Catalogue details

Licence: In copyright

Credit: Recent improvements in methods for the biological purification of sewage / by W.J. Dibdin. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    to 830 yards, had treated 100,000 gallons daily, plus subsoil water. This quantity is equal to over 200,000 gallons per yard, so that five yards will have treated 1,000,000 gallons, the cost for which, for renewing the material in the bed from a reserve supply, would be 5«. 10'/. Dangers of Sludge Heaps. The danger to public health from sewer gas is commonly referred to, but little reference is made to the danger arising from accumulations of sewage sludge either in the form of heaps of pressed cake, or lagoons filled with the foul abomination collected in detritus or other tanks. This question has been brought prominently foi-ward by the researches of Mr. John P. Lord, P.E.M.S., fonnerly Professor of St. Xavier's College, Calcutta, &c., which were detailed by him in a paper contributed to the Institute of Sanitary Engineers, in which the following conclusions were set out:— Presh sludge may contain as many as five hundred and fifty-five million three hundred and thirty thousand (j5j,330,()()0) microbes in each grain of solid matter, which all grow at the ordinary temperature of the air. In liquid sewage the highest number recorded is eleven million two hundred and sixteen thousand per cubic centimetre (11,216,000). The concentration of bacteria in sludge is therefore very apparent. Instead of decreasing on exposure to air the bacteria flourish amazingly. In a gramme of weathered sludge at least a month old the average number was two thousand six hundred and forty-one million nine hundi-ed and forty-four thousand (2,641,944,000). The above grow in air. In addition an average of one million two hundred thousand per gramme (1,200,000) developed in the absence of air. The following are the most prevalent bacilli in fresh sewage:— Fluorescens Liquefaciens, Proteus Vulgaris, Filamentosus, Mesen- tericus, Mycoides, Subtilis, and Coli Communis. In addition to these Mi'. Lord found the bacillus of typhoid fever (see block), B. Typhi Abdominalis, Eamosus, Gloacaj Superficialis, Neobacillus, Preudenreichii and Spirillum Plavenc in its three varieties. The anaerobic bacilU found consisted of Clostridium Pretidum, Tetani, &c. . j. i n- The gases evolved by the anaerobes in growth were most foul smolhng. the rotten egg odour of Clostridium and the bad garlic smell of the Tetanus being overpowering when the tubes were opened. Mr Lord then made a series of experiments to ascertain the effect of the growth of organisms on the surface of the sludge and found anthrax developed fairly rapidly, diphtheria and typhoid (Figs. 1 and 2) also, but not so readily. After a time the anthi-ax was entirely ui a spore form, m which condition it could be blown about readily and thus cause infection.
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