Use: 



Water 



quantities, 



bgy 



Industrial-steam electric generation 2,856 



Other 6,529 



Commercial power 34,849 



Total 44,234 



A further detailed breakdown of these water 

 quantities can be made by identifying the water as 

 fresh or brackfish. 



Recirculation: The quantities of water used for 

 fresh water recirculation are shown in the tabula- 

 tion and are based on the following assumptions: 



Fresh water recirculation, bgy 



Commercial 

 Industrial power 



Intake 374 



Recirculation 16,533 



Consumption 249 



Discharge 125 



102 



5,815 



Total 



476 



22,348 



317 



159 



Some plants recirculate brackish water, but be- 

 cause of the limited number of such operations, 

 water quantities have not been established for this 

 type of cooling. 



Significant Indicators of Water Quality 



Table V-4 shows the quality characteristics of 

 surface waters that have been treated by existing 

 processes to produce waters acceptable for boiler 

 makeup and cooling. 



Table V-5 shows quality requirements for both 

 boiler-feed water and cooling water at point of 

 use. These values are for waters that have already 

 been processed through any required "external" 

 water treatment equipment, such as filters or ion 

 exchangers, but have not yet received any required 

 application of "internal" conditioning chemicals. 

 This information is included to allow estimation of 

 costs of treating raw waters. It does not imply that 

 waters of poorer quality cannot be utilized for 

 boiler-feed water or cooling in specific cases. 



The values for water quality requirements at 

 point of use must be considered only as rough 

 guides. Thus, in the case of boiler-feed water 

 makeup, the maximum concentrations refer to the 

 upper end of the steam pressure range shown. 

 Usually, more liberal concentrations are accepta- 

 ble in feed water for boilers operating at lower 



pressures within each range. However, even here 

 there are many deviations in practice because of 

 differences in the construction and operation of 

 different boilers. For example, all other things 

 being equal, the higher the makeup rate, the higher 

 the quality of the makeup water should be. 



Water treatment processes 



The water treatment processes marked by an 

 "X" in the following table are used in producing 

 water of the appropriate quality for either cooling 

 or boiler makeup. Commonly used internal con- 

 ditioning processes are also included. Not all of 

 these processes are used, however, if the raw water 

 quality is such that the treatment is unnecessary. 



Cooling 



Suspended solids and colloids 

 removal: 



Straining x 



Sedimentation x 



Coagulation — 



Filtration 



Aeration 



Dissolved solids modification 

 softening: 



Cold lime — 



Hot lime soda — 



Hot lime zeolite — 



Cation exchange sodium_ — 

 Alkalinity reduction: 



Cation exchange hydro- 

 gen — 



Cation exchange hydro- 

 gen and sodium — 



Anion exchange — 



Dissolved solids removal: 



Evaporation — 



Demineralization — 



Dissolved gases removal: 



Degasification mechani- 

 cal 



Degasification-vacuum __ X 

 Degasification-heat — 



Internal conditioning: 



pH adjustment X 



Hardness sequestering.. X 



Hardness precipitation.. — 

 Corrosion inhibition 



general — 



Corrosion embrittlement. — 

 Corrosion oxygen 



reduction — 



Sludge dispersal X 



Biological control X 



— X 



Once Recir- Boiler 



through culated makeup 



NOTES. — " — " Not used. 



"X" — May be used. 



193 



