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On-line zeta potential analyzer for water treatment processes

The Zetasizer WT is a fully automated system that delivers lab quality on-line zeta potential measurements. This enables real-time monitoring of flocculation process performance and efficient charge neutralization.

The Zetasizer WT combines Malvern Panalytical’s industry leading Electrophoretic Light Scattering technology with two decades of expertise with in-process measurements to produce a dedicated on-line zeta potential analyzer for water treatment plants.

Technical specifications

Sample requirement
Sample flow rate 100 - 350 LPH (fast loop)
Sample flow rate 0.5 - 2 LPM (measurement)
Measurement type Zeta potential
Measurement principle Laser Doppler micro-electrophoresis
Result output frequency 3 minutes typical, programmable
Operation 24hr continuous
Range of zeta potential measurement +/- 500 mV (+/- 90 mV on HMI interface)
Size range 3.8 nm to 100µm
Enclosure rating IP54, indoor use. Limited capability to NEMA 4X
Power 90 - 132 VAC, 180 - 264 VAC, 50 - 60 Hz, 6 A
Dimensions (W, D, H) 855 x 686 x 1720mm
Weight 160 Kg
Compressed air purge 1.5LPM, 6-10 bar, ISO 8573-1:2010 [0.7.2] (optional)
Operating environment
Temperature range 0°C to 40°C
Humidity 5-95% non-condensing
Maximum sample pressure 6 bar


Eliminate sample cross contamination between zeta potential measurements using a completely disposable cell.

The zeta potential of colloids and molecules is extremely sensitive to contamination from components of a previous sample used in a measurement cell. The use of a disposable cell completely eliminates this potential contamination issue.

The folded capillary cell provides the benefits of the accuracy of measurement of a capillary cell with the ease of use of a disposable cell.

Although, disposable, including the electrodes, for low conductivity samples each cell can be used for hundreds of measurements if required.

The cell can be used with the autotitrator, where multiple measurements are routinely done over a wide pH range.

Key features

  • No more guess work – accurate and reliable results in [mV] provide a clear range for dosing control.
  • Respond to changes in raw water before they cause filtration problems!
  • Reduce chemical use to optimum for forming a stable floc. Overdose no more!
  • Completely automated zeta potential analysis with results in minutes.
  • Results sent to SCADA via OPC, Modbus or 4-20mA
  • Minimal maintenance
  • Easy measurement of grab samples on the same system.
  • HMI for local control and setup
  • On board computer for autonomous operation
  • Sample flow and temperature sensing

How it works

The Zetasizer WT connects to a sample stream coming from the plant after coagulants have been added and mixed into the water. The system uses a pump to flow a sample through the analyzer`s flow cell where zeta potential measurements are made. Sample is then pumped into waste or returned back into the process and replaced with a fresh sample in a continuous, automatic cycle.

Automation and analysis is controlled by an on-board industrial computer running Malvern Panalytical Link II software. 

Measurement results are displayed on a local HMI screen as well as exported into plant SCADA via OPC, Modbus TCP/IP or wired 4-20mA connections.

Results are used by treatment plant operators or a plant control system to adjust coagulant dose required to keep zeta potential in a pre-determined range – typically between zero and a slight negative charge.

Zetasizer WT also allows easy measurement of grab samples from other areas in the process, effectively doubling as a laboratory system.

  • Environmental
Malvern PanalyticalMalvern Panalytical was formed by the merger of Malvern Instruments Limited and PANalytical B.V. on 1st January 2017, has headquarters in both Almelo (the Netherlands), and in Malvern (UK), and employs over 2,000 people worldwide. The combined entity is a strong player and innovator in the materials characterization market and will leverage the strengths of the individual companies in their end markets, ranging from building materials to pharmaceuticals and from metals and mining to nanomaterials.
[Zetasizer WT, water treatment processes]