Resumen:
Percrystallization was evaluated at laboratory scale to determine the
suitability of the technique as the core evaporation technology for achieving
Zero Liquid Discharge (ZLD) of a Kraft pulping effluent. Compared with
conventional evaporation/crystallization, percrystallization allows to operate
at room temperature, using relatively unexpensive membranes and vacuum
to allow evaporation of aqueous brine solutions. This suggests that it could
be an efficient alternative to evaporate the concentrated brine from an
upstream desalination stage (electrodialysis), as less energy would be
required to heat the solution and allow evaporation. Percrystallization of
electrodialysis brine was successfully achieved at laboratory scale, but high
energy consumptions over 3,000 kWh/ton were measured. After this, the
energy consumption of an optimized industrial system (with an efficient
vacuum pump) was computed based on theoretical equations, indicating
energy consumptions between 110-150 kWh/ton, still higher than those of
traditional ZLD systems based on brine crystallizers (around 90 kWh/ton).
Percrystallization could be an efficient alternative for low scale applications
where the temperature of the solution must remain low (e.g., less than 40°C).