Use of spent caustic stream of a petrochemical complex as paper mill digester liquor

Spent caustic stream of a petrochemical complex has been concentrated to paper mill digester liquor for sulfate pulp process through evaporation and chemical addition. Cost comparison has been done for the following two alternative routes against a typical paper mills cost to produce digester liquor. Alternative 1: Evaporation followed by chemical addition Alternative 2: Only chemical addition.