New Desalination Configurations and Technologies for Recovery Increase and Concentrate Minimization

Concentrate minimization and recovery enhancement are currently key issues in the application of desalination technology for the treatment of brackish waters for municipal water applications. For example, reverses osmosis (RO) recovery for brackish waters currently ranges from 60 to 85 percent, which results in a large volume of concentrate. The disposal of such quantities of concentrate is not only a loss of valuable resource and energy, but also a challenge in itself, especially for inland facilities, and with regards to environmentally sustainable disposal options. Though several concentrate disposal methods are available (such as surface water or sewer discharge, deep well injection, evaporation ponds, thermal evaporation, etc.) there are inherently high costs, accessibility constraints, permit challenges and other limitations associated with all methods. These limitations are becoming more apparent and challenging with stricter regulations. The emerging and promising approaches to desalting and its concentrate treatment that aim to enhance overall recovery and reduce concentrate volume are of key interest to the future success of this technology. This paper presents an overview and discussion of the promising and emerging methods in the industry for concentrate minimization and recovery enhancement. The work forms part of an ongoing AWWA Research Foundation project (Project. #3030). The project focuses on the various methods of recovery enhancement and concentrate minimization, including identification and assessment of the promising and emerging methods and technologies.