The invention provides a hydrofluoric acid wastewater treatment method
that achieves efficient recovery of hydrofluoric acid from hydrofluoric
acid wastewater and also achieves sufficient reduction in the
hydrofluoric acid concentration of the dehydrofluorinated water after
treatment.The hydrofluoric acid wastewater treatment method comprises the
following steps: a hydrofluoric acid concentration step (S1) comprising
concentrating hydrofluoric acid wastewater by evaporation to produce a
concentrated hydrofluoric acid water and a hydrofluoric acid-containing
vapor; a dissolution step (S2) comprising bringing the hydrofluoric
acid-containing vapor obtained in the hydrofluoric acid concentration
step (S1) into contact with dissolution water to dissolve the vapor; a
neutralization step (S3) comprising bringing the residual hydrofluoric
acid-containing vapor left from the dissolution step (S2) into contact
with an alkali to produce a neutralized liquid and a dehydrofluorinated
vapor; and a condensation step (S4) comprising condensing the
dehydrofluorinated vapor obtained in the neutralization step (S3) to
produce condensed water.