(606a) Zero Liquid Discharge (ZLD) System for Flue-Gas Derived Water From Oxy-Combustion Process

Researchers at the National Energy Technology Laboratory (NETL) located in Albany, Oregon, have patented a process – Integrated Pollutant Removal (IPR) that uses off-the-shelf technology to produce a sequestration ready CO₂ stream from an oxy-combustion power plant. Capturing CO₂ from fossil-fuel combustion generates a significant water product which can be tapped for use in the power plant and its peripherals.  Water condensed in the IPR^® process may contain fly ash particles, sodium (from pH control), and sulfur species, as well as heavy metals, cations and anions.  NETL is developing a treatment approach for zero liquid discharge while maximizing available heat from IPR.  Current treatment-process steps being studied are flocculation/coagulation, for removal of cations and fine particles, and reverse osmosis, for anion removal as well as for scavenging the remaining cations. After reverse osmosis process steps, thermal evaporation and crystallization steps will be carried out in order to build the whole zero liquid discharge (ZLD) system for flue-gas condensed wastewater. Gypsum is the major product from crystallization process.  Fast, in-line treatment of water for re-use in IPR seems to be one practical step for minimizing water treatment requirements for CO₂ capture. The results obtained from above experiments are being used to build water treatment models.