Volume 6

Report of the Commissioners appointed in 1898 to inquire and report what methods of treating and disposing of sewage (including any liquid from any factory or manufacturing process) may properly be adopted.

  • Great Britain. Royal Commission on Sewage Disposal.
Date:
1902-1915
Catalogue details

Licence: Public Domain Mark

Credit: Report of the Commissioners appointed in 1898 to inquire and report what methods of treating and disposing of sewage (including any liquid from any factory or manufacturing process) may properly be adopted. Source: Wellcome Collection.

    904/1008 (page 38)
    Scud der. 38 Enclosure II. to Mr. Frank Scudder s Reply. DISSOLVED OxyGeEn Test. THE reagents employed are as follows :— (1.) Indigo solution. Take 3 grammes of indigo carmine, dissolve in hot water, and make up to- one litre. (2.) Sodium hyposulphite (NaHSO,). Sulphurous acid (SO,) gas is passed through a saturated. solution of carbonate of soda, until saturated with SO,. 50 cc. of the bisulphite solution is placed in a 60z. stoppered bottle, and 10 grammes of zinc dust added, and shaken well for two minutes, keeping the liquid cool by holding under running water. Then fill the bottle with water, and allow to stand 15 minutes, when the top liquid can be decanted into a half Winchester bottle which is. at once filled with tap water. Some operators now add milk of lime, and form a neutral hypo- sulphite of lime, but I prefer to use the liquid without the addition of lime. From this stock solution, a dilute hypo solution is made up to such a sirength that 15 to 20cc. will decolorise 25 cc. of the Indigo solution. Sane In order to keep the stock hypo for a month, it is advisable to cover the liquid with a layer of petroleum, or to turn the bottle neck downwards in a vessel of water. Methoa of procedure.—100 cc. of the sewage effluent are added to 900 cc. tap-water in a half ~ Winchester bottle, well shaken, and allowed to stand half an hour to allow small air bubbles to rise to the surface. The temperature of the liquid is noted. Two 10 oz. stoppered bottles are- then filled with the diluted effluent, and placed in the incubator at 75° Fahr. The dissolved oxygen is estimated at start, after 24 hours, and after 48 hours. 4 Calculation : emperature 22° C, 1 litre of aerated distilled water at 22° C. contains 6-04 cc. oxygen per litre. 25 cc. Indigo solution = 19°8 cc. hypo solution. 100 ce. Dis. Aq. at 22° C. = 7°7 cc. hypo solution. . 604 + 77 = 0°0784 cc. oxygen the value of 1 cc. hypo. but 25 cc. Indigo =19°8 cc. hypo. *. (0784 x 19°8 | | = 0°0621 = value of 1 cc. Indigo in terms of oxygen. 25 z 25 cc. Indigo = 22:0 cc. hypo. 100 cc. diluted effluent = 9°5 cc. hypo. but 1 cc. Indigo = 0:0621 cc. oxygen. S00 alex tap ————— = 0:0705 = oxygen value of 1 cc. hypo for the day. 22 and 00705 x 9°5 x 10 = 6°70 ce.’s oxygen per litre in the effluent examined. 100 cc. of the original sewage effluent is presented to 6°7 cc.’s dissolved oxygen. 1 cc. oxygen weighs 0:022123 grain. . 67 x 10 x 4543 x 022 = 6:7 grains dissolved oxygen per gallon of sewage effluent. Dissolved oxygen apparatus:—The arrangement of the apparatus as used by me for the determination of the “ dissolved oxygen” in water is similar in principle to that described by Roscoe and Lunt, in the Chemical Society Journal, Vol. 55, August, 1899, page 552, also see Sutton’s Volumetric Analysis, 8th edition, page 297, et seq., but modified so as to make it portable. The main parts of the apparatus are Ist, a hydrogen apparatus which can give a constant. stream of pure hydrogen under pressure, and 2nd, the estimation bottle having an indiarubber stopper with six holes holding three burettes (for sample, indigo, and hypo respectively), an inlet and outlet tube for hydrogen, and a tube for emptying the bottle. The apparatus was designed to be the same size as an ordinary Orsat gas analysis apparatus. The photographs shew the- apparatus as in use, and its construction is as foflows :— Hydrogen apparatus.—Bottles A B C form a simple arrangement for the generation of hydrogen under pressure, acting in the same manner as a “ Kipp.” From the top of bottle (A), a tube: passes to bottle (D), in which there is a little caustic soda. The stopcock (1) regulates the supply of hydrogew which passes to bulb (E), filled with beads, and saturated with alkaline pytogallic to. - free the gas from any trace of oxygen. The hydrogen then divides, one part going to the hypo- sulphite stock bottle (H), while the remainder passes to the top of the hypo burette, which has a T tube fused on, and allows the burette to have an atmosphere of hydrogen above the hypo, while the remainder of the gas passes through stopcock (5) into the bottle (G), from which it escapes through the water seal tube (L) to the atmosphere. To saturate the beads with alkaline pyrogallic.—Each day before the apparatus is used, the beads. in (E) have to be saturated with pyro from the bottle underneath, which is done thus: stopcock (1) is closed and the threezway stopcock (3) opened to the air. The three-way stopcock (2) is opened gradually, and the hydrogen forces the pyrogallic from (F) up to (E); stopcock (2) is then turned to ailow the pressure in bottle (F) to escape, when the liquid falls back to (F). This is once repeated to saturate thoroughly. Stepcock (2) is then shut off from the hydrogen, and No. 1 opened, when the hydrogen drives any, air from (E) through (3) to the atmosphere; No. 3 is then turned to allow hydrogen to get into bottle (H). ae .