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Sewage Purification Works, Dalmarnock
| Firmenname | Sewage Purification Works, Dalmarnock |
| Ortssitz | Glasgow |
| Ortsteil | Dalmarnock |
| Art des Unternehmens | Kläranlage |
| Quellenangaben | [Institution of Mechanical Engineers (1895) 474] |
| Zeit |
Ereignis |
| 02.05.1894 |
Eröffnung |
| ZEIT | 1895 |
| THEMA | Beschreibung |
| TEXT | These works, erected by the Police Commissioners, were opened on 2nd May 1894, and serve the eastern district of the city. The main sewer 7.5 feet diameter is brought down the centre of Swanston Street, and led into the entrance chamber, which is 17 feet long by 9 feet wide and 16 feet 1 inch deep, and is situated at the north-west corner of the precipitation tanks. On the east side, in front of three 4-feet penstocks, is a wrought-iron grid to catch heavy floating matter. The sewage is taken thence into the machinery building by three 4-feet by 4-feet invert channels, placed underneath the precipitation tanks and aerating beds, to the west side of the catchpits, where it has to pass through three 4-feet rotary screens of cast-steel, with bars K inch apart. It then flows into the 5-feet feed channels on the west side of the catchpits.
Lifting plates 4 feet by 6 inches are securely attached at intervals of 4 feet to the rotary screens for the purpose of taking up all floating matter, and depositing it into a wrought-iron trough placed in froid aka depth of 10i feet below the floor line. The rubbish here collected is passed into a square wrought-iron self-tipping bucket, which is daily emptied into the destructor furnace. The screens work at as angle of 45°, and make 14 revolutions a minute.
The sewage flows from the 5-feet channel into two catchpits, each 47 feet 10 inches long by 20 feet broad. Three V shaped troughs run along the bottom of each catchpit, the bottom of the trough being 28i feet below the floor line. A screw conveyor, making 41 revolutions a minute, pushes the solid matter forwards to the elevator trough, the bottom of which is 33i feet below floor line; and it is raised by the elevator buckets into a railway wagon on the floor level. The sewage free of heavy matter then flows from the catchpits into a 10-feet channel on the east side, leading to the pump well, which is 31 feet 1 inch below floor line.
The suction pipes from the centrifugal pumps are led down to within 15 inches of the bottom. The water is raised through these into a 3.5 feet cast-iron pipe placed against the south wall of the pump room, through which it flows into the mixing pit, where the chemicals are introduced. There are two 18-inch and two 15-inch pumps, with a total of 350 horse-power, capable of raising 11 million gallons per hour. Two 6-inch pulley-pumps on the east side of the pump room discharge the sewage water into lime-mixers over the sludge tank. This water is used for making milk of lime, and for dissolving the sulphate of alumina. The pulley pumps are driven from the main line of shafting, which is worked from the engine room, where there are two pairs of compound condensing engines, each 120 horse-power. The sewage water is used for the condensers; and these engines also drive a dynamo, which supplies all the lighting for the works. The mixing pit, 10 feet square by 8 feet deep, is divided down the middle by a tongue going down to within 31 feet of the bottom; and the sewage mixed with the chemicals has to pass under the tongue into an outlet channel, 8 feet wide by 31 feet deep, which leads to the feed channels of the precipitation tanks.
The sludge from the precipitation tanks is brought into the works by a 6.5 feet main channel, falling 3 inches in 100 feet from the tanks. In front of each section of these tanks is a channel for the sludge to run into a tank under the mixing rooms. This tank is 80 feet long, 46 feet wide, and 21 feet below the floor line at the west end and 23 feet at the east end. In the north-east corner is a low-pressure sludge-ram, capable of holding 1,800 gallons, through which the sludge is raised by compressed air into two mixers in the lime room. Here hot lime is added to facilitate the pressing.
In the low floor of the sludge-receiving room are four high-pressure rams, each holding 900 gallons. The sludge runs from the mixers by gravitation through a 6-inch cast-iron pipe into these rams, whence it is raised by compressed air at 100 lbs. pressure per square inch into the presses. When the air has blown the sludge from the high-pressure rams, it is transferred into the large low-pressure ram in the north-east corner of the sludge tank, thereby effecting a saving of 80 per cent. of compressed air, by raising sufficient sludge into the mixers for recharging the high-pressure rams again. The compressed air is supplied by two high-pressure engines to the north of the rams.
In the press room on the top floor are seven sludge-presses, each when charged holding 25 cwts. of pressed sludge-cake, which is dropped through shoots in the floor into railway wagons underneath. The sludge, street sweepings, and ashpit ashes are mixed together and sold for manure. On this floor is also a large cast-iron sludge-tank, into which crude sludge can be raised, for the purpose of mixing with very dry ashes without putting it through the presses.
In the boiler shed are six Lancashire boilers, 28 feet long by 7 feet diameter, working at a pressure of 100 lbs. per square inch. The fuel used is the coke from the filtration beds, when it has become too dirty for filtering any longer. At the north end of the shed is a Babcock and Wilcox economiser, through which the feed-water is pumped into the boilers at 200'; and north of the engine-room is a workshop for repairs.
In each section of the works, eastern and western, there are twelve precipitation tanks, each holding 81,000 gallons; they are worked on the intermittent system; and each can be charged in seven minute. Precipitation takes place iu forty-five minutes; then floating aims are lowered to draw off the clearer water, which passes across aerating beds. These tanks can be worked on the continuous system, which however has the disadvantage of allowing the sludge to accumulate, and the effluent can never be so clear; whereas by the intermittent plan, sludge cake can be formed within five hours after the sludge has left the main sewer.
The filtering beds are twenty downward coke filters, each 40 feet long, 10 feet wide, and 31 feet deep, through which the water passes and rises in a 3-feet open channel. It again passes down through forty sand filters, each 40 feet by 38 feet and 21 feet deep. When the sand becomes dirty on the top, it is washed and used over and over again. Finally the effluent water passes into the river Clyde. The works at present constructed can deal with ten million gallons of sewage a day, or about one-fifth of that from the entire city; and they can be extended to treat twice the quantity. The buildings, tanks, and filtering beds cover 19 acres, and 9 acres more remain available. The land cost £38,000, and the buildings, tanks, and machinery £67,000. The manager is Mr. Thomas Melvin. The number of men employed is fifty, of whom the majority are on eight-hour shifts, as the work has to go on continuously. |
| QUELLE | [Institution of Mechanical Engineers (1895) 473] |
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