. Cyclopedia of textile work : a general reference library on cotton, woollen and worsted yarn manufacture, weaving, designing, chemistry and dyeing, finishing, knitting, and allied subjects . tlet soft and readyfor use. 250. Filtration of Water. Two different methods of filtra-tion are in practical use, /. .., the so-called European and Ameri-can systems. In the European sijstem, a large filter bed is prepared five orsix feet in thickness and constructed of coarse gravel at the bottom,gradually growing finer as it approaches the top, where there are 237 228 TEXTILE CHEMISTRY AND DYEING severa
. Cyclopedia of textile work : a general reference library on cotton, woollen and worsted yarn manufacture, weaving, designing, chemistry and dyeing, finishing, knitting, and allied subjects . tlet soft and readyfor use. 250. Filtration of Water. Two different methods of filtra-tion are in practical use, /. .., the so-called European and Ameri-can systems. In the European sijstem, a large filter bed is prepared five orsix feet in thickness and constructed of coarse gravel at the bottom,gradually growing finer as it approaches the top, where there are 237 228 TEXTILE CHEMISTRY AND DYEING several inches of sand. The water to be filtered is allowed to flowover this filter bed and gradually percolates through it. After thefilter bed has been in use for some time, a thin deposit of silt andorganic matter deposits upon the upper surface and graduallycoats each individual grain of sand in the upper layer. Thisupper layer filters out all mechanical impurities present in thewater and reduces the number of bacteria present in the water toa marked degree. With the European system a filter bed of larcre area is neces-sary, and it is not very efiicient until it has been inor)eration for. Fig. 79. Water Filter. several weeks, but with proper care it can then be used for a longtime. This method of filtration is extensively used for the purifi-cation of drinking water in large cities, but less frequently in in-dustrial establishments. The Ajnerican syHem aims to produce, by artificial means, acondition similar to the European system. Cylindrical filters areconstructed and filled with broken quartz, coke, and sand, as illus-trated in Figs. 78 and 79. Before the water enters this filter a small amount of alumi- 238 TEXTILE CHEMISTRY AND DYEING 229 nium sulpLate is added, which reacts with impurities present inthe water and forms minute particles of aluminium hydroxide,which are of a gelatinous nature. This gelatinous precipitate col-lects upon the individual particles of sand in the
Size: 1613px × 1549px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherchicagoamericansch
