The Sludge Blanket Monitor is used to monitor and control the blanket level in settlement tanks for a wide range of industries and applications including;

  • Primary Sedimentation
  • Secondary and Final Clarifiers
  • Remote Settlement Tanks
  • Sludge Thickeners
  • DAF Tanks
  • Sequential Batch Reactors (SBR)
  • Lamella Clarifiers
  • Counter Current Decantation (CCD) Tanks
  • Mining & Process Settling Ponds and Lagoons

The unit is particularly suited for identifying auto-desludging and overspill alarm signals and for monitoring the general biological health of thick sludge blankets.


  • Sediment relative density throughout the tank shown on the LCD display.
  • Improved efficiency and control of the treatment process.
  • Warning of biological upset or hydraulic imbalance.
  • Reduce site operational costs significantly with improved process control.
  • Reduced sensor maintenance (air purge cleaning).
  • Improves health and safety as no manual readings are needed.

Installation and Operation

The Ultrasonic Transducer is immersed just below the surface of the water and pointed directly at the bottom of the tank. The Monitor uses time-of-flight echo processing and advanced algorithms to lock on the true sludge interface level and ignore the floating solid particles and troublesome rag layers.

The unique algorithms have been designed to automatically filter all floating particles and electrical noise interference for unmatched performance.

A simple 3-button keypad is used by the operator to input the tank depth. The Monitor automatically does the rest with its advanced echo processing and signal gain adjustment.

The LCD screen displays the echo profile for visual confirmation of the sludge level relative to the tank bottom. A 4-20mA signal is provided proportional to the sludge level for SCADA input.

To overcome build-up of solids on the sensors an air purge facility removes debris and reduces the need for continual maintenance.

Alarm states can be programmed for sensor failure/scum detection and high-level sedimentation. An optional data storage facility enables the operator to observe the sedimentation performance over any historical period.

This Monitor sets itself apart from other sludge blanket monitors by using extremely high ultrasonic frequencies of 1.1MHz, and coupled with advanced signal processing, this allows the detection of very small particles even in hostile environments.


Raymond Karsten
Instek Control
Tel. +27 12 998 6326

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