put into operation the past two or three years. The first one, I believe, to use mechanical means for handling the sludge, was Brownville, Texas, started in August, 1923. The engineer there built a tank with a mechanism in it for distributing and mixing or agitating the sludge. On visits of some two or three of our engineers since then, we have never discovered any scum on the tank or odors about the plant; and while no laboratory analysis has been made of the sludge, from all appearances it is in every way equal to the best Imhoff sludge. This brings up the question of scum discussed in the previous paper and this one. At Charlotte, North Carolina, the City Engineer installed a separate digestion plant for 50,000 people. In this particular place the flow passes through five screens, then through a sedimentation tank with mechanism for removing the sludge to separate digestion tanks. These separate digestion tanks, however are plain tanks with no mechanism for controlling the sludge or distributing or mixing it. Operation began in January, 1925. To date they have had some trouble from odors about the plant, as a great deal of the sludge is in the form of scum on top of the tanks rather than sludge in the bottom. One of the engineers reports that their sewage is quite strongly acid, which may explain why they are getting more of an acid fermentation than alkaline digestion. At Bartow, Florida, a separate digestion plant was put into operation in September, 1924, and from last reports they are getting well digested sludge from the digestion tank. That tank also has a mechanism for distributing the fresh sludge over the surface of the liquid and withdrawing ripe sludge from the bottom. It is a cylindrical tank about 15 feet deep and 26 feet in diameter, and from reports there has been no accumulation of scum on the top, or odors about the tank whatever. These observations indicate, at least, that if the digestion tank is fed every day with small quantities of fresh sludge and means provided for agitating the digested sludge so that the fresh sludge can be properly seeded down as it is put into the tank, you will get uniform digestion and gradual elimination of the gases as formed, with a smaller chance for sludge rising to the surface than would occur if you were to pump large quantities at infrequent intervals with no means of distributing and mixing it. of Service In 1842 at Mohawk, N. Y., a sanitary sewer 150 feet long and with an internal diameter of 6 inches was built with concrete pipe to serve the home of General F. E. Spinner, former Secretary of the Treasury of the United States. In 1922, 80 years later, this sewer line was inspected by H. M. Ranny, Consulting Engineer of that city who reported the pipe to be in excellent condition. The permanence of concrete pipe sewers is further emphasized by the many years of service they have rendered in other cities of which the following examples are typical: Concrete pipe sewers built in Nashua, N. H., in 1868; Kokomo, Ind., in 1874; Racine, Wis., in 1883, and in Butte, Mont., in 1889, are still giving satisfactory service. The fact is that concrete sewers have been used extensively both in this country and abroad since the development of the art or science of sewage disposal. Today concrete sewer pipe meeting the requirements of the most exacting engineering specifications are being manufactured in standard sizes ranging from 4 inches to 108 inches internal diameter, and are being used on a large scale for sewer construction in all sections of the country. For full information write for Bulletin C-3. American Concrete 111 West Washington Street Chicago 5 AIR-LOCK APPARATUS For Sewers and Sewage Disposal. Catalog No. 21-Pneumatic Sewage Ejectors. Catalog No. 22-Flush Tank Siphons, Water Regulators. Catalog No. 23-Automatic Siphons for Large Municipal Disposal Catalog No. 24-Automatic Controls for Operating Sand Filters and Catalog No. 25-Automatic Siphons for Domestic Septic Tanks. Catalog No. 28A-Wood Trash and Sewage Pumps. PACIFIC FLUSH-TANK COMPANY Singer Building, New York 4241 Ravenswood Ave., Chicago SALT GLAZED VITRIFIED CLAY SEWER PIPE STANDING THE TEST OF TIME ON ALL SEWER WORK VITRIFIED CLAY SEWER PIPE is not the kind of sewer pipe that needs taking up and repairing inside of a few years. IT PROTECTS ITSELF against disintegration, deterioration; its hard, smooth glazed surface defies the infiltration or seepage substances. The "slippery finish" leaves no "toehold" for the stuff that builds up and clogs ordinary sewers. For Full Particulars Write EASTERN CLAY PRODUCTS ASSOCIATION HENRY T. SHELLEY, Sec.-Mgr. Telephone Spruce 5029 |