SIX® stands for Suspended Ion eXchange process and is designed to remove Dissolved Organic Carbon (DOC) from the water to improve membrane filtration performance. SIX® also removes sulphate, nitrate, and phosphate. Removal of DOC minimizes membrane fouling and reduces the formation of trihalomethanes  (THMs) after final disinfection with chlorination.

The philosophy of the SIX® process is based on an advanced plug flow reactor followed by a specially designed lamella settler. The settled resin is then completely regenerated and re-used. The continuous (modelled) adsorption process operates under stable kinetics.

The design of SIX® itself is far more compact, has lower resin concentration and lower resin inventory, lower salt usage, higher effluent quality and better control of the adsorption process than other processes available anywhere on the market. It allows for the use of different types of resin.

SIX® is leading edge technology, proven and validated as well as completely controllable.

  • Unit is very compact with small footprint
  • Model is fully validated
  • Reduced resin inventory
  • Full control
  • 100% regeneration of dosed resin
  • No risk of resin binding
  • Short resin contact times; no risk of biofouling
  • Low resin attrition; minimal resin loss
  • Can be used with all commercially available resins

NOM-removal at SWTP Andijk (Netherlands) with a New Anion Exchange Process, called SIX®

Abstract: The new developed ion exchange process SIX presents an advanced solution for a world-wide challenge: How to remove NOM/DOC as a first step in surface water treatment to improve efficiency of downstream processes and to improve water quality. Besides the possibility to treat water containing suspended matter another advantage is the fact that the process has advanced to an economical and technical feasible process, guaranteeing a stable water quality, resulting in a large tolerance for flow fluctuations and relatively low contact times and small resin inventory. Most important advancement however is that almost every commercially available resin can be used creating the desired flexibility in suppliers for water supply companies. This paper describes the process and generates advantages and disadvantages compared to conventional technologies leading to the world first full-scale application with a capacity of 5500 m3/h.

An Introduction to SIX®