An apparatus for evaporating waste water and reducing flue gas acid gas emissions includes an evaporator device configured to receive a portion of flue gas emitted from a combustion unit and waste water for direct contact of the flue gas with the waste water to cool and humidify the flue gas, and to evaporate the waste water. An alkaline reagent as well as activated carbon may be mixed with the waste water prior to waste water contact with the flue gas. Solid particulates that are dried and entrained within the cooled and humidified flue gas can be separated from the flue gas via a particulate collector.