THE UTILIZATION OF THE PRECONCENTRATION FOR THE ARTIFICIAL WASTEWATER BY FREEZE-CONCENTRATING TECHNIQUE WITH MIXING NON-AQUEOUS PHASE LIQUID- NOVEC 7300

This study was carried out lo determine the removal of COD from aqueous solution using layer crystallization method. In this study, the influence of several parameters, such as adding as not-aqueous phase liquid, 3M Novec 7300 (FN), freezing temperature, initial COD concentration, and the stirring speed upon removal ratio of COD were carried out. Results showed that the removal ratios of COD in the ice with FN adding were higher than that of no FN adding. When the freezing temperatures of the solution were decreased from 5 to -25 °C, the removal ratios of COD in the ice were decreased. The values of removal ratios of COD for the wastewater concentrations of 250 mg/L, 500 mg/L and 1000 mg/L with FN adding ratio of 10% were 93.36%, 91.52% and 89.91%, respectively. The driven force of concentration poor, water molecules in liquid was diffused to the interface of solid and liquid, while the pollutants near the interface of solid and liquid was diffused to liquid.