{TAIL ~ Presence} of brine water with a salinity of {HEAD ~ 8 to 12%} is crucial because it is used to regenerate the cation exchanger such that: 
{ TAIL ~ Presence } of brine water with a salinity of { HEAD ~ 8 to 12 % } is crucial because it is used to regenerate the cation exchanger such that :
TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH