Freeze Concentration Applied to Hazardous Waste Management

Abstract

Typically as compounds crystallize they reduce in volume, as their solid density is generally greater than the liquid form. Water is unique in that as it crystallizes its density decreases as the solid ice expands. So is it with this emerging technology. Freeze concentration, the name typically referring to the crystal1ization and separation of ice from aqueous solutions, is expanding into new areas of water recovery. Freeze concentration has been applied to various food products since the Middle Ages. Potable water from seawater was recorded in the 17th century. Today this technology is emerging as a new unit operation for the recovery ofwater from RCRA hazardous waste streams. Typical streams are high in water content and contain soluble components that pose not only risks for humans but are harmful for typical bio-treatment systems. For this reason they require extreme treatment measures to prevent release into the environment. This paper will briefly describe the techniques in use today for treatment of this type of aqueous waste and provide an in depth review of freeze concentration and its potential in this sector of wastewater treatment.