Low temperature desalination by Eutectic Freeze Crystallization (EFC)： Towards achieving zero liquid discharge in water treatment

摘要

Water treatment processes such as nanofiltration (NF) ， reverse osmosis (RO) and ion exchange (IEX) produce aqueous waste streams with a high salt content. The disposal of such brines is a growing concern in many parts of the world. Traditional disposal methods include discharge to sea or other surface water bodies, discharge to sewer, deep well injection, distribution over land or storage in evaporation pounds. However, these disposal means are often hindered because of unavailability, costs of transportation, environmental impact, regulatory requirements and/or public perception. The need is to find efficient, cost-effective and sustainable management options for saline waste streams which does not simply shift a water quality problem from one area or one user to another.A promising way of managing the saline aqueous waste streams is to consider them a resource of salt (s) and water (Kim 2011). There are two benefits associated with this approach. First, the recovery of salt and subsequent use (sale or integrated use) may offset the high operating costs that are typically associated with Zero Liquid Discharge (ZLD) processes (Kim 2011) Second, reclamation of pure water from the waste stream reduces the volume of liquid waste to be disposed, eventually leading to cost savings.