Industrial Water Conditioning Processes Part II WENDELL W . CERNA, Hall Laboratories, Pittsburgh, Pennsylvania
T N PART I' the importance of industrial water supplies to our war effbrt and the need for correcting CIANGB~I N
1
natural chemical characteristics of water supplies were discussed and a number of the orinci~almethods described. In the oresent article ittention will be kiven to additional meihods of treatment, with exampfes of results obtainable by the diierent processes. RESULTS OBTAINABLE BY VARIOUS TREATMENTS OF ONE RAW WATER SUPPLY
Table 2 contains exam~lesof changes in the com" position of a raw water supply which can be produced by various methods of treatment described in Part I. A knowledge of such results as these is important in selecting the method of water conditioning which will give the greatest benefit in any particular case. With some types of raw water, two or more diierent treating methods or combinations of treatment may give almost equally satisfactory water. In such situations installation costs, space, and cost of housing required, as well as the cost of chemicals needed per unit of water, are determining factors in the selection of the proper treating system. For example, methods 3, 4, 5, and 6 in Table 2 represent methods which can be used for conditioning raw water of the analysis given in column 1 for use as feed water make-up to steam generating boilers. Methods 3 and 5, however, do not lower appreciably the high silica concentration of the water and would only be used for relatively low-pressure boiler operation. Method 4 includes silica removal by means of dolomitic lime, and this water would be suitable for make-up water to boilers operating a t much higher pressures. Both methods 3 and 4 retain high total dissolved solids in the water, however, which would require a high blowdown rate of about 15 per cent to limit total solids in the boiler water to 2000 p.p.m. In addition, the residual hardness of this water is great enough so that if heat exchangers or economizers are used for increasing the temoerature of the feed water before it reaches the boiler, some further precipitation of the residual calcium Tnrs JOURNAL. 20, 107-15 (1943).
TABLE 2 ANALYSBS OB
V A s l O W MBTaOoP OI
TBBATIENT
~.~
TW.. . .bf~T
WATBB P~ODUCBD BY
~ (Described ~
BC~OW)
Re~ulls Erorasrd in Porlr per Million ~ ~ ~ ~ ~ 1 2 3 4 5 6 7 8
~ ~ , " P ~ t ~ t ~ ~ $ ~ 0256108 )101 . . . . 36 . . . 36 ..
............
51 20 ... 10 12 12 12 2 sulfate (sod 12 12 116 116 Chloride (Cl) 39 39 39 39 39 39 39 2 25 6 28 Silica (SiOd 6 28 6 28 25 calcium ( c a ) 20 8 6 6 1-2 1-2 1-2 1-2 Magnesimm (Mg) 6 1 1 1 < I t l
