Civil Engineering Reference
In-Depth Information
Spray irrigation of concentrate almost always requires dilution prior to irrigation
so as to:
Prevent pollution or degradation ground water resources while meeting regulatory
requirements.
•
Reduce the chloride content to acceptable levels so as not to damage grass or
crops being irrigated.
•
Other Methods for Concentrate Disposal
The Brine Concentrator
The brine concentrator (BC) is most often designed as a
vertical-tube, falling film evaporator, although horizontal spray film and plate type
evaporators are also used in this application. The brine concentrator blowdown is
usually processed further to a solid waste in either solar ponds or a crystallizer.
The common characteristic of most brine concentrator designs is the circulation of
a slurry of calcium sulfate (CaSO
4
) crystals, which act as seeds. Calcium sulfate and
other scale-forming compounds preferentially precipitate on the circulating seed crys-
tals over the heat transfer surfaces to prevent scaling. The development of the seeding
technique for calcium sulfate and silica allowed brine concentrators to process waste
waters at or near saturation in calcium sulfate and silica to very high concentrations.
Up to 20 percent total solids by weight is often achievable in the brine concentra-
tor discharge, while a distillate of better than 10 ppm TDS can be achieved. Figure
23-27 shows the typical components of a brine concentrator.
93
Mechanical vapor recompression (MVR) evaporators, or more simply, vapor com-
pression (VC), utilize a compressor to raise the condensing temperature and pressure
Deaerator
Vent
Brine
Concentrator
Acid
Brine
Feed
Compressor
Plate
Heater
Concentrated
Waste
Distillate
Pump &Tank
Brine Feed
Tank
Feed
Pump
Recovered Water
Recirculation
Pump
Fig. 23-27.
Typical components of a brine concentration (
Source:
Reference 92)
