The daily morning journal and courier., 1897-03-31
A GIGANTIC FILTER,


 The largest, the costlest and best til- ter plant in the world has just been completed at Davenport, Iowa. Prac- tical men, whose experience has made their opinions worthy of respectful at tertion, say that this plant really solves the water supply question for nearly all western cities. The cost of the plant IS $1, 200, 900. The ten double-filter shells, which contain the immediate water sup ply, have capacity of 7,500,000 gallons. The Mississippi river is the source from which the water supply originally comes. The water Is drawn from point in the bed of the river nearest the channel down into a tunnel that passes under the rivers bed for con siderable distance, Through this tun- mel it sweeps to the pump wells, ana thence into the filters. There is no dan l ger of contamination, as far as the sewage is concerned, for the point in l the river from which water is secured is mile and a half above the govern ment bridge and the point at which the Davenport sewers enter the river. At | this same point the Mississippi has a current of about five miles an hour and | dashes over the Rock Island rapids, 1 giving 1t complete aeration, oxydation and dilution, all of which tend to its purification.
 The filter plant is in itself most marvellous sight. Each of the filter shells Is 91a feet in diameter and 32 feet long. They are built of homogeneous steel of tensile strength. The water company has so far built about thirty seven miles of mains, into which the purified water flows from the filters.
 Despite the fact that there are ten filter shells, so delicate is the construc- tion, from a mechanical standpoint, of the entire plant, that the filters can be used either one at a time or in their entirety, as circumstances may make it advisable. As an indication of the eff fort that has been made to provide this plant with every possible means of pur- flying the water, it may be stated that each filter is about three-quarters full of white sand, amounting to about thirty carloads for all the filters.
 This sand is brought from Horn isl and, in the Gulf of Mexico. The pecu- liar nature of this sand is that each grain is of almost equal texture and a perfect crystal. This is brand new, and a very costly departure. The ordinary sand that is used for Altering purposes is porous, and therefore does not in al
 respects answer the requirements. This
 however, is the first time that a city o
 any size has so filtered it's water sup
 ply.
 It must be remembered that water al
 ways contains microbes. Sometimes
 they are so infinitesimally small tha
 only a magnifying glass of exceeding power will detect them. If there wer, no sand in the filters that was absolute
 ly impervious to the attacks of the mi : crobes these little seeds of death would
 be quite likely to find 1odgment in tn pores of the sand. There they woult
 die and rot,and in short time the sanC t would become a fruitful source of dis ? ease rather that plant to purify water This is why Horn island sand is usec
 in Davenport.
 If all the rivers in the country, bar : ring the Chicago river, had been con I sdered as maximum test for this bi, s plant no better selection could hay ' been made than the Mississippi river : While the bed of this river is compose,
 to a great extent of constantly shifting E E sand there Is at all times pronounce'
 sediment in the water which gives : that peculiar yellowish color, which ha !, made it famous as the only real wate : in America that hardly resembles wate
 at all, with the exception that it is Ii ' quid in form. At certain seasons of tn vna> If er1a ba fil1a5 with MicSicS;Dr
 river water and allowed to stand for
 few moments, it will be found that al
 most one-fourth of the glass, from tn u bottom up, will contain liquid muC
 That is why 1t is so often said that tn \. persons who drink unfltered Mississip = pi river water absorb their peck of dir
 every forty-eight hours
 So the task of the big filter plant a
 Davenport is no light one, and tn :. amount of dirt and impurities that ar ' removed from the 7,500. 900 gallons tn |, filters contain is naturally tremendou u in quantity. Especially does this fac n prove impressive when it is considere l. that the 100000 gallons the filters hol
 simply constitute the amount that is i t them at all times. Of course the wate $ is constantly changing. Every momeT n it is being pumped out into the thirty s seven miles of mains that wind lik ;. huge snakes beneath the surface of Da i venport's streets. To filter the entir Q water supply of a city is a giganl1 Q task.
 Q The method of filtration is interestin :, and entirely new, because it must b
 remembered that there is not in exist ii ence any Altering plant that approacht d this in magnitude or completeness [; the way of possessing every requisit
 for removing impurities from water t the first place, the water as it come y from the Mississippi river via the tur n mel beneath the rivers bed, is forced b
 pumps through twenty-inch feed main e into the filters. Then 1t passes dowr i. l ward through five feet of sand an
 thence through a peculiarly shape
 screen consisting of extremely fine slit
 sawed through cylinders of heav n seamless tubing After this it goes ir
 to the mains and is forced out to th d consumer.
 e Now look at the water and compare If with the muddy, amber-colored f1ui Il that flows into the filters from the tur U U neL It has become as bright, as cles $ and as sparkling as if it came from y spring.
 't The sediment and all the microbe
 that the unfltered water yields nece: