Potential of freezing in wastewater treatment: soluble pollutant applications.

When wastewater containing only soluble pollutants is frozen gradually, ice crystals grow from the pure water only, while pollutants are rejected into the liquid phase thus increasing their concentration. In this way, pure water can be removed from various wastewaters. Two kinds of wastewater were studied: synthetic wastewater containing water and one or more soluble pollutants, and industrial wastewaters (urban wastewater and cutting oil wastewater). In most cases, separation efficiency close to 100% was achieved. A large range of pollutant concentrations was studied in order to determine the limits of freezing separation.