Cantor lectures on bacterial purification of sewage / by Samuel Rideal.

  • Rideal, Samuel.
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Cantor lectures on bacterial purification of sewage / by Samuel Rideal. 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.

    17/40 (page 15)
    the Mersey and Invell Joint Committee, and will, in our judgment, be the means of greatly improving the waters of the Ship Canal. The Local Government Board held an inquiry at Manchester, on January I2th and 13th, 1899, with reference to the application of the City Corporation to borrow ;^i6o,ooo for purposes of sewerage and sewage disposal. It was explained that Manchester had tried filtration by land and chemical treatment, but neither of these had been satisfactory. Eleven tanks had now been constructed at Davyhulme, each 300 ft. long by 100 ft. wide, and 6 ft. deep, with a united capacity of 12 to 15 million gallons, equal to half a day's dry weather flow. The population of Manchester was 520,000, and was increasing at the rate of 4,700 per annum. The tanks were originally used as chemical filters, the treatment and removal of sludge costing about ^^i/.ooo a year, the chemicals alone reaching ^^90 per week. It was then proposed to utilise these tanks for settling the raw sewage, which would subsequently pass through si.xty acres of double-contact beds filled with coke breeze. An effluent would then be produced without the use of land, which would practically conform to the present requirements of the Mersey and Irwell Joint Committee. It is also stated that if the double contact did not suffice, they would employ a third contact. The inquiry was j adjourned for further details. The first contact ^ beds of 30 acres were to be constructed of I coarser material than the second 30 acres of second contact beds. From a later report it appears that nitrifi- cation has at length been attained, the highest result being o-68 of nitric nitrogen, but the average only reaching 0-27. In the Tables given they are called double filtration ex- periments, and as a fact they are neither anaerobic nor properly aerobic as the poor result in nitrification shows. Better results, as we shall see later, could probably be obtained by making the first filtration more anaerobic and by ensuring better aeration in the second filters. It will also be noticed that sedimenta- tion in tanks is required by Manchester as essential for the proper working of the contact beds. This sedimentation, therefore, is the equivalent of the screening adopted by Mr. Dibdin, at Sutton, and the chemical precipita- tion of the earlier c.Nperiments before passing on to the one acre filter bed in the London County Council experiments. [Note.—The adjourned inquiry was concluded on May 1st, 1899, when the experts gave satisfactory reports of the working of the experimental beds since January. On learning that the effluent was passed into the Ship Canal, the Local Government Board inspectors observed that pending the report of the Royal Commission, the Board was not pre- pared to depart from what it has laid down as to the provision of land for the treatment of effluent. The Corporation ha^•e shown that 300 acres of land could be made available below the filter beds, if necessarj'.] Lecture III.—Delivered January 30, 1899. Almost all of the processes for sewage treat- ment already described have been of a mixed or compound character, and not purely bacte- rial. And to a great extent this accounts for the numerous failures, either through expense, or irregular working, with such a variable liquid as sewage. Even when it was recognised that nearly all the destruction of effete matter was accomplished by minute organisms, there was a natural reluctance to trust entirely to the action of bacteria, from fear of the multiplica- tion of pathogenic forms. Numerous attempts \i