Synergistic Systems for Water Reuse and Desalination

A.E. Childress
University of Southern California,
United States

Keywords: wastewater, reclamation

Summary:

Coastal seawater desalination and wastewater reclamation facilities produce two main waste streams – a concentrate/brine stream and a treated wastewater stream, which are typically discharged to the ocean. Currently, the only synergistic use of these waste streams is dilution of the RO concentrate stream with treated wastewater; the blending of these streams is central to solving the RO concentrate disposal dilemma. However, one disadvantage is that the water resource within the wastewater is utilized only for dilution prior to disposal, and therefore, is lost as a potential supply of water for a more valuable purpose. In this presentation, theoretical, experimental, and system-scale analyses to evaluate other blending scenarios for these waste streams will be discussed. Flow rates and water quality of candidate streams are quantified to assess energy consumption, potable water generation, energy recovery, and waste stream management for alternate scenarios. The ultimate goal of the research is to synergistically utilize the two waste streams to achieve highest beneficial use of both streams, while minimizing energy consumption and environmental concerns. Challenges and opportunities facing system-scale integration of each scenario, including regulatory concerns, are also considered. Proposed scenarios are compared to the base case of co-discharge of treated wastewater with RO concentrate. This project also has implications for inland brackish water desalination where disposal of RO concentrate is perhaps even a more serious concern. Considering the large number of ocean and brackish water RO facilities that are in planning, construction, and operation in the west and other arid regions of the world, results from this investigation have broad reach.