Report to the corporation of Belfast on a bacterial investigation of the experimental contact beds for the treatment of sewage / [J. Lorrain Smith].

  • Smith, J. Lorrain (James Lorrain), 1862-1931.
Date:
1901
Catalogue details

Licence: In copyright

Credit: Report to the corporation of Belfast on a bacterial investigation of the experimental contact beds for the treatment of sewage / [J. Lorrain Smith]. 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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    The results of the chemical analysis of the sewage by Professoi Letts are as follows .— Percentage Purification as shown by Kjeldahl’s method. Highest result after 2nd contact 77 % of Purification. Average of all experiments 57% Brick beds 60% 55 Coke beds 50% 5 5 This set of-results shows that we can in a measure locate the agency which has the strongest effect in causing the disappearance of unoxidised nitrogen. It is especially associated with the bricks of the deeper part of the lower bed. The agency, however, is here merely a degree or two more efficient than that associated with the other bricks. In each case there is a remarkable disappearance of unoxidised nitrogen. The only point about the more efficient bricks which I observed was that they were more richly covered with sediment consisting of the vegetable and animal organisms already referred to. In the vessels in which the bricks were placed for the purpose of testing their action on the dilute broth, a copious layer of sediment, similar to that on the bricks, formed at the bottom. This when analysed (Kjeldahl) showed large quantities of nitrogen in the uno&idised form. The following experiment gives the details of one such observation. The broth after having been in contact with the bricks for six days was taken for analysis in two portions. One portion was filtered, and 50 c.c of the filtrate were put in each of two flasks and analysed for nitrogen. The filtrate was found to contain only 85 per cent, of the unoxidized nitrogen of the original solution, or, to keep to our former method of expression, there had been a loss of 65 per cent, of the original unoxidized nitrogen. On the other hand, portions of the broth which were not filtered, and which purposely were made to contain a large amount of sediment yielded unoxidized nitrogen per c.c. amounting to more than 150 per cent, of that in the original diluted broth. On these grounds, therefore, it seems clear that in the plant and animal life associated with the surface deposit on the bricks there is an agency which has the most striking power in causing the disappearance of unoxidized nitrogen from solution ; whereas in the former experiments,
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