Water scarcity has become an important issue in many developing and developed countries. To conserve valuable water resources, the need to reclaim and recycle industrial wastewater is increasing. The objective of this study was to establish a protocol for the treatment of salty water and wastewater containing up to 57 g/L NaCl. This project was aimed at the development of an optimized process using an electrodialysis (ED) and reverse osmosis (RO) hybrid system. An energy analysis revealed that the optimal operating condition consisted of first removing the majority of salt (down to 10 g/L) using ED, followed by a RO process to bring the water to the desired purity. By performing ED on 10 L of a 50 g/L NaCl solution with an effective membrane area of 0.0512 m2, the salt concentration could be reduced to 10 g/L using an applied voltage of 20 V for 90 minutes. The recovery was about 70%. The RO process was used to treat the ED diluate at an applied pressure of 1.96 MPa. An RO rejection of 96.6% was obtained and had a recovery of 3.5%. Industrial polycarbonate wastewater containing 57.5 g/L NaCl was treated with the ED-RO process, and the energy consumption was similar to that for the NaCl model solution. The required treatment time was longer for the wastewater due to the presence of co-ions. For water purification, the ED-RO hybrid system uses less energy than either RO or ED systems alone. This approach provides an efficient and economical evaluation tool for water recovery from high-salinity water and wastewater streams.

Electrodialysis of high-salinity wastewater and process optimization of a hybrid system with reverse osmosis for water recovery

246th National Meeting (2013)

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