ELECTRO-MEMBRANE TECHNOLOGIES FOR ZERO LIQUID DISCHARGE

Water is the most important source for the future. Technologies able to decrease water consumption or prepare better water quality are increasing the quality of life all over our planet. New production technologies, being more effective, faster and able to produce more complex products than before, also require better water quality for their operation. In order to comply with this demand, legislature norms for water treatment are getting tighter, and for some industries Zero Liquid Discharge (ZLD) has already become a new standard. ZLD process can be simplified into three main parts: ۱) pretreatment part, ۲) concentration part, ۳) evaporation and crystallization part. From an economic point of view, the last part of evaporation and crystallization is the most energy intensive. Due to this fact, it is necessary to increase the concentration of salts in feed in order to decrease the volume of water for the evaporator. Electrodialysis (ED) represents an interesting method of how to rapidly increase the concentration of feed stream comparing to widespread pressure processes like Reverse Osmosis (RO), commonly used in the concentration step. ED decreases the operating expenditures of theevaporator and positively affect the economy of the whole process