A waste water processing system includes an upflow contacting column having a flue gas input for receiving flue gas having a temperature of at least 500 degrees F., a waste water input, and a flue gas output. The waste water input is coupled to a fluid injector, e.g., atomizing nozzles, positioned in the throat of a Venturi portion of the upflow contacting column or in a sidewall of the throat of the Venturi portion of the upflow contacting column. The flue gas in the upflow contacting column has a high velocity, e.g., a gas velocity exceeding 65 fps in the throat of the Venturi portion of the upflow contacting column at a position where the fluid injector is located. Drying additives such as recycled ash, lime, and/or cement may be, and sometimes are, input into the upflow contacting column downstream of the waste water input.