Ion Exchange - SIX® - Nijhuis Saur Industries

Your challenges

Water treatment facilities today face complex demands. SIX® helps you respond to these challenges:

Organic load in source water

High levels of naturally occurring organic matter (NOM) and dissolved organic carbon (DOC) can interfere with downstream processes, increasing fouling, reducing filter life, and contributing to disinfection by-product formation like trihalomethanes.

Waste management constraints

Traditional treatment processes often generate complex waste streams that are difficult or costly to manage. Utilities need solutions that minimise waste volume and simplify disposal or recovery.

Pressure to reduce operational costs

Rising energy, chemical, and maintenance costs are driving the need for more efficient treatment strategies. Solutions that improve upstream performance can significantly reduce downstream operational expenses.

Regulatory pressure on emerging contaminants

Utilities face growing regulatory demands to address contaminants beyond NOM, including PFAS, nitrates, sulphates, and other trace substances, requiring more flexible and targeted treatment options.

How does it work?

SIX® uses suspended ion exchange resin to remove dissolved contaminants such as DOC, sulphate, nitrate, phosphate, and possibly even PFAS. The process includes:

Contact stage: Raw water is mixed with ion exchange resin to adsorb target substances. Resin is mixed by air in a five-chamber contactor. The resin is suspended, so the process is ideal for waters with suspended solids.
Separation stage: The process uses lamella settlers to separated the resin from treated water. Since the resin is never pumped, it moves through the system via gravity and eductors, preserving resin integrity and reducing energy use.
Regeneration: All resin is regenerated after a single pass through the contactor. The regeneration occurs in batches, with regenerant used up to five times before disposal. Salt is usually used as regenerant, but in some cases bicarbonate is a possibility.

This approach offers high recovery rates (typically 98–99%), low waste generation (1–2%), and flexibility in resin selection, including options for targeted removal of specific substances.

Our positive impact

SIX® helps water utilities tackle complex treatment challenges with a flexible, efficient, and sustainable suspended ion exchange solution:

Early removal of organics

SIX® removes natural organic matter (NOM) early in the treatment chain, improving the performance of downstream systems. This enhances the removal of pollutants, and significantly reduces the formation of disinfection by-products such as trihalomethanes.

Flexible resin selection

Compatible with nearly all commercially available resins, including those designed for specific contaminants like PFAS, nitrate, and sulphate. This flexibility supports easy integration into existing infrastructure and helps utilities respond to evolving regulations on emerging contaminants.

Efficient regeneration & Low waste

Resin is regenerated in batches with minimal waste (1–2%) and high recovery rates (98–99%), reducing environmental impact and operational costs. SIX® typically achieves 40–60% NOM removal, and up to 90% under specific conditions, depending on feed water quality.

Versatile regeneration options

The regeneration process typically uses salt as the regenerant, but bicarbonate can be used as an alternative, particularly in low-alkalinity waters. Bicarbonate regeneration adds alkalinity and can lower total dissolved solids (TDS) when paired with pellet softening, improving water palatability.

Do you want to know more about SIX®?

Download brochure

References

See all our references

Municipal
Municipal drinking water

Andijk, North Holland, the Netherlands

Andijk III Water Treatment Plant (PWN)

More about this reference

Municipal
Municipal drinking water

Plymouth, England, United Kingdom

Mayflower Water Treatment Works (South West Water)

More about this reference

Frequently asked questions

What contaminants does SIX® remove?

SIX® was originally developed to remove dissolved organic carbon (DOC) and natural organic matter (NOM), but it can also target nitrates, PFAS, ammonia, and other emerging contaminants, depending on the resin used. This flexibility helps utilities meet evolving water quality standards.

SIX®