Fresh water supply and municipal wastewater treatment are essential for every built environment. Wastewater discharge and carbon emission are also intensive from a built environment to the natural environment. During the practice of municipal wastewater reclamation to meet the fresh water demand, reverse osmosis (RO) and electrodialysis (ED) are truly the only water desalination processes currently in practice for the entire range of total dissolved solids (TDS) from 400 – 40,000 mg/L. For high recovery of 80% or more, RO is energy intensive even for a feed water with a TDS of 1000 mg/L and demand significant pre-treatment to avoid membrane fouling. We would like to present for the first time a hybrid ion exchange desalination (HAIX-Desal) process that does not require any semi-permeable membrane and can desalinate lean brackish water (TDS≤1500 mg/L) using CO2 as the sole source of energy and chemical regenerant with simutaneous nutrient recovery effects. It connects the carbon emission and wastewater discharge to the water supply for the built environment, relieve the burden on the natural environment. Hybrid anion exchanger with dispersed ZrO2 nanoparticles (HAIX-NanoZr) and a shell-core weak-acid cation exchange (SC-WAC) resin form the heart of the process. CO2 at 10 atmosphere pressure is the only chemical needed to sustain the process. In contrast to conventional deionization plant, the anion exchanger, i.e., HAIX-NanoZr precedes the cation exchanger or SC-WAC to take advantage of the unique carbonate chemistry for desalination. CO2 serves concurrently as both an acid (i.e., H2CO3) and a base (HCO3-) for the HIX-Desal process. Municipal secondary wastewater (Bethlehem, PA) and synthetic brackish water were used in the experimental study to validate the basic premise of the process.

Novel hybrid ion exchange process for municipal wastewater reclamation and nutrient recovery driven by waste carbon dioxide

2019 Fall National Meeting

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