Specification of William White : precipitating sewage and other foul waters, &c.

  • White, William.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Specification of William White : precipitating sewage and other foul waters, &c. Source: Wellcome Collection.

    6/10 (page 4)
    White's Impts. in Precipitating Sewage and other Foul Waters, fyc. .. —.—........ i i i. - ■ ' ... - - ■ 1 ■ r , Instead of milk of lime simply I find the purifying and clarifying power of such method of precipitation is greatly increased by using lime charcoal, which I prepare by calcining an intimate mixture of peat or sawdust with chalk or lime, or magnesian limestone, or other cheap and convenient substances, resulting on calcination in a combination of 5 carbon with calic oxide or calcic and magnesic oxide. I mix the peat or sawdust by preference with chalk or limestone in such proportions as to yield a product containing about 90 per cent, of lime and 10 per cent, of charcoal, I calcine the mixture in iron or clay retorts at a tempera¬ ture sufficient to expel the carbonic acid from the chalk. If lime be 10 substituted in making the mixture a lower temperature will suffice in the calcining process. I thus obtain charcoal in a very porous and divided state disseminated amongst lime. When this lime charcoal is used as a precipitating agent the lime acts both chemically as a precipitant and also mechanically to cause the 15 charcoal to sink through the sewage, so bringing it into intimate contact with it, without which the powerful defecating and deodorising properties of the charcoal could not be excited. v - ■; ^ / A very advantageous way of treating sewage and other similar foul waters is to add to them first bone or mineral phosphate of lime rendered 20 soluble by means of hydrochloric or other acid, and afterwards to use lime charcoal to precipitate the phosphate of lime, together with re¬ maining impurities in the sewage. In some cases in place of lime charcoal I prepare and use in a similar manner a lime coke. I mix intimately, small coal or coal dust with 25 chalk or lime, and introduce the mixture into the retorts at gas works. The result is a form of lime charcoal, which I call “ lime coke 99 such as I require for precipitation. This lime coke may conveniently contain about 80 per cent, of carbon. Coke being of a denser nature -than charcoal it is desirable to employ a larger proportion. 30 I also prepare a similar precipitating material, which I designate phosphatic charcoal or phosphatic lime charcoal, from an intimate mixture of pulverised or precipitated mineral phosphates, calcic, or aluminous (which phosphates usually contain a considerable proportion of calcic carbonate) with peat or other carbonaceous matter, and use the 35 game in like manner as the lime charcoal. ’ ~ ..