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Microwave dry cake solids measurement

Valmet Dry Solids Measurement - Valmet DS

Valmet Dry Solids Measurement (Valmet DS) for dried wastewater sludge (dry cake), is installed after the dewatering machine at municipal wastewater treatment plants. Accurate measurement of biosolids provides significant savings in polymer dosage, energy, and dewatered solids transportation.

A unique solution for dry cake measurement

Valmet Dry Solids Measurement (Valmet DS) utilizes microwave technology, requiring no special certification or safety procedures, to make a stable and accurate solids measurement for dewatering control in wastewater treatment. Valmet DS extracts a continuous sample from the falling cake flow after a centrifuge or screw press and measures the solid content before returning the sample back to the process.


  • 100% safe microwave technology
  • Up to 25% less polymer usage
  • Minimized transportation costs of dry cake
  • Optimized polymer dosage and torque of the centrifuge
  • Reduced fuel consumption at combustion plant
  • Optimization of total solids (TS) value of dry cake
  • Better oversight of dewatering and process efficiency


Continuous measurements bring cost savings for wastewater management

Feedback control using the accurate dry solids measurement provided by Valmet DS can fully optimize polymer dosage and provide energy savings through better torque control of the centrifuge. Maximizing drying efficiency to a target dry cake solids content can provide additional savings with reduced transportation costs and improved power boiler combustion.

  • Reliable screw-based sampling
  • Cake solids range up to 35 %
  • Built-in calibration routine
  • Industrial Internet remote access

In addition to full remote access to Valmet DS functions, measurement data, alarms and diagnostics via the Industrial Internet, the Valmet DS Ethernet connection can be used for local control with a laptop or tablet computer during commissioning.


Valmet DS is typically located in the downfall section of the dry cake. A sample retrieval screw feeds a return screw which compresses and pushes the sample
through the microwave sensor chamber before being returned to the process.

The Valmet DS measurement is based on multivariable microwave resonance, compensated for variations in material temperature and calibrated during commissioning with samples taken from the screw and oven dried.


Solids Measurements For Better Wastewater Control

Download Valmet Wastewater Guide to learn how reliable online solids measurements can be used to optimize and improve plant operations and process.