Ion Exchange

Over the past decade, management of contamination in groundwater and surface water supplies has been growing in importance around the globe. Communities are reliant on the quality of these water supplies for drinking water, for irrigation and for industrial uses.

Historically, management of ground and surface water for complex contaminents such as organics was challenging and often expensive. Common practice involved oxidation in the presence of catalysts (advanced oxidation-AOX), air stripping or adsorption onto activated carbon. While these practices still have valuable applications, the introduction of ion exchange resins into this area provided an attractive alternative.

Strong Base Anion (SBA) and Weak Base Anion (WBA) resins provided significant improvements on traditional adsorption technologies for treating organic hydrocarbons such as activated carbon. In many applications, anion IX resins showed significant improvements in operating capacity, reducing replacement or regeneration frequencies. Regeneration could also be performed in-situ rather than relying on ex-situ steam based processes.

Higher capacity resins allowed for adsoprtion/IX technologies also meant that high energy/cost operations such as AOX and air stripping were less viable.

Similarly, Strong Acid Cation (SAC) and Wak Acid Cation (WAC) resins provide alternative solutions to traditional metal hydroxide and metal sulphide precipitation and clarification processes. Metal sulphide treatment is becoming increasingly unpopular in remediation processes. Sulphide precipitation typically utilises sodium sulpide solution, which is extremely challenging to manage. Significant care must be taken to avoid generating anoxic conditions in receiving water ways. Care must be taken to avoid the generation of H2S gas in process piping and equipment.

Metal sulphide precipitation has often been implemented for the management of heavy metals when treated water criteria (e.g. ANZECC 2000 guidelines) are below the solubility limits of metal hydroxide species.

Ion exchange processes remove these same contaminants (e.g. Lead, Copper, Nickel, Cadmium, Zinc, Chromium) to below ANZECC guidelines values. Due to the highly selective nature of these resins, run times can be in excess of several years without requiring resin replacement or regeneration.

Hydroflux has a wide range of HyX ion exchange processes for management of groundwater and surface water. Some examples of these include:

• Metal and Heavy Metal Remediation
• PFAS remediation
• Perchlorate remediation
• Remediated soil washing plant wastewater treatment and recycling
• Organic Carbon (Tannin/Humic Acid) Treatment of surface water
• Water Softening
• Nitrate Removal

Some of the advantages of the HyX processes include;

• Custom, in-house design & manufacture of FRP Vessels (up to 2m bed depth) provides effective, high capacity treatment at low cost
• Proprietary resin loading and unloading systems for easy media change-out
• Wide range of resin options
• In-house design and fabrication of complete treatment process to ensure effective resin pretreatment

In power generation, high purity water forms an essential part of the steam cycle. This demineralised, or “ultra pure” water is necessary to minimise scale formation and corrosion within the boiler and turbine.

Scale formation leads to reduced energy efficiency and increases maintenance costs. In large scale industrial processes, where considerable volumes of steam are consumed as part of the plant operation require large high efficiency demineralised water treatment plants.

Industrial processes with high UPW requirements, such as pulp & paper and petrochemical industries often utilise ion exchange systems to generate fresh demineralised water. Produced demineralised water flow rates output by ion exchange processes are typically in excess of 100-150m3/hr. The Ion exchange processes will typically have a higher operating recovery than other bulk demineralisation processes such as RO.

The typical high flow demineralised process involves dedicated cation/anion exchange columns followed by a mixed bed process, which contains both cations and anion resins within a single ion exchange vessel.

The cation resin removes all positive ions, including heavy metals, calcium, magnesium, potassium and sodium and replaces them with hydrogen (H+) which is loosely bound to the polymer matrix.

Similarly, the anion resin removes all negative ions, including sulfate, chloride, nitrate, carbonate as well as weakly ionised carbon dioxide and silica.

In some processes, additional ion exchange pre-treatment is required with weak base anion IX systems for management of organic carbon impurities or additional cation IX for management of heavy metals and hardness.

Hydroflux and our partners Flootech specialise in the manufacture of condensate polishers for the power, pulp & paper, mining, petrochemical and other heavy industries. We design and manufacture a wide range of systems for condensate polisher plants

• High Pressure/High temperature pre-filtration systems
• Cation, anion & mixed bed vessels in a variety of materials including Stainless Steel, FRP, Painted Mild Steel and others
• Regenerant preparation vessels (conversion from Cl to OH form)
• Waste regenerant treatment
• Resin replacement and resin unloading systems
• O2 and CO2 reduction using Membrane Degassing

In addition to the above, the treatment process may also involve pre-treatment steps to manage other impurities in the feed water.

• Pre-screening with Hydroflux range of high capacity FlooScreens
• Gross solids and algae removal with HyDAF and FlooDAF systems
• Final solids polishing with HyPURE MMF and/or HyPURE UF filtration
• Pre-treatment solid waste management with sludge dewatering solutions

In power generation, treatment of recovered condensed steam forms a pivital role in the overall plant energy efficiency. As steam passes through production areas, or through a steam turbine, it collects impurities from the surfaces in which it comes into contact.

These impurities build up in the condensate, as it is returned back to the boiler and reprocessed. To minimise energy losses through unnecessary boiler blow downs, as well as to reduce the amount of high purity demineralised make-up water is needed on site, high purity ion exchange processes are implemented.

The typical condensate polishing process involves either dedicated cation/anion exchange columns or more typically a mixed bed process, which contains both cations and anion resins within a single ion exchange vessel.
The cation resin removes all positive ions, including ammonia (NH4+), calcium, magnesium, potassium and sodium and replaces them with hydrogen (H+) which is loosely bound to the polymer matrix.

Similarly, the anion resin removes all negative ions, including sulfate, chloride, nitrate, carbonate as well as weakly ionised carbon dioxide and silica. These ions are replaced by hydroxyl (OH-) ions, which combine with the excess H+ to form water. Only the residual 10^-7 mol of H+/OH- remains, which

To maximise the life of the resin, Hydroflux provide dedicated regeneration systems including specialised high purity air scour and backwash processes necessary to separate the cation and anion resins within the mixed bed vessels. Waste treatment systems are also necessary for managing the spent regenerant prior to discharge from site.

Hydroflux and our partners Flootech specialise in the manufacture of condensate polishers for the power, pulp & paper, mining, petrochemical and other heavy industries. We design and manufacture a wide range of systems for condensate polisher plants

• High Pressure/High temperature pre-filtration systems
• Cation, anion & mixed bed vessels in a variety of materials including Stainless Steel, FRP, Painted Mild Steel and others
• Regenerant preparation vessels (conversion from Cl to OH form)
• Waste regenerant treatment
• Resin replacement and resin unloading systems