Table 6 Summary of treatment options available for coal seam gas co-produced water (© Copyright, SKM 2011). Treatment Description Contaminant Suitability/Application Limitations Additional process Waste option removal requirements Membrane Water subject to high Broad constituents Well-suited for ranges Stringent Multi-media or High Desalination pressure through a including salt, heavy of dissolved contaminants, required. membrane filtration. concentration (RO) semi-permeable metals and trace including TDS, heavy brine High energy demand. Post-treatment, membrane for organic matters metals and organics including chemical May not remove all separation of adjustment (for SAR). contaminants to contaminants minimum levels. Ion exchange for improving recovery May make water too clean for receiving environment. Electrodialysis An electrochemical Broad constituents, Well-suited for removal of No removal of Filtration for SS High – (ED) and process in ions including salt and TDS, mainly for charged uncharged forms of removal. concentration Electrodialysis migrate through heavy metals contaminants, including contaminants. brine GAC/Advanced Reversal (EDR) and heavy metals Not economical for oxidation/wetland for membranes feed TDS > 4000 the removal of as a result of their mg/L. uncharged forms of attraction to two contaminants electrically-charged electrodes Thermal Water subjected to a Broad constituents, Well-suited for ranges High energy demand Post-treatment, High Desalination phase change for including salt, heavy of dissolved contaminants, unless heat source is including chemical concentration purification metals and trace including TDS, heavy already available. adjustment brine organic matters metals and organics Ion Exchange Charged resin replaces Targeted Not practical for gross TDS No reduction in None Regeneration conductive salts with contaminant removal removal. May be suited for salinity. fluid with high replacement ions (e.g. reduction of targeted salt content Irreversible organic H+ and OH-) contaminants and/or matter adsorption. for the desalination processes
Table 6 Summary of treatment options available for coal seam gas co-produced water (© Copyright, SKM 2011). Treatment option Description Contaminant removal Suitability/Application Limitations Additional process requirements Waste Membrane Desalination (RO) Water subject to high pressure through a semi-permeable membrane for separation of contaminants Broad constituents including salt, heavy metals and trace organic matters Well-suited for ranges of dissolved contaminants, including TDS, heavy metals and organics Stringent required. High energy demand. May not remove all contaminants to minimum levels. May make water too clean for receiving environment. Multi-media or membrane filtration. Post-treatment, including chemical adjustment (for SAR). Ion exchange for improving recovery High concentration brine Electrodialysis (ED) and Electrodialysis Reversal (EDR) An electrochemical process in ions migrate through membranes as a result of their attraction to two electrically-charged electrodes Broad constituents, including salt and heavy metals Well-suited for removal of TDS, mainly for charged contaminants, including and heavy metals No removal of uncharged forms of contaminants. Not economical for feed TDS > 4000 mg/L. Filtration – for SS removal. GAC/Advanced oxidation/wetland for the removal of uncharged forms of contaminants High concentration brine Thermal Desalination Water subjected to a phase change for purification Broad constituents, including salt, heavy metals and trace organic matters Well-suited for ranges of dissolved contaminants, including TDS, heavy metals and organics High energy demand unless heat source is already available. Post-treatment, including chemical adjustment High concentration brine Ion Exchange Charged resin replaces conductive salts with replacement ions (e.g. H+ and OH-) Targeted contaminant removal Not practical for gross TDS removal. May be suited for reduction of targeted contaminants and/or for the desalination processes No reduction in salinity. Irreversible organic matter adsorption. None Regeneration fluid with high salt content
background-review-co-produced-water.docx