Ultrasonic Sludge Blanket Monitoring System

The ENV120 Ultrasonic Sludge Blanket Level Meter, utilises enhanced ultrasonic technology to measure the sludge interface level in various types of clarifiers, settling tanks and thickeners with superior accuracy and reliability.

The instrument continuously provides the user with important information which includes numeric and graphic screens representing the distance to the blanket, an echo profile image to ensure correct configuration during commissioning and saved data analysis. Additional features such as ASF (Abnormal Signal Filter), allows elimination of irregular field noise which can result from moving structures intermittently obscuring the signal. The ENV120 technology additionally incorporates a compressed air cleaning system to maintain the sensor in optimum condition and guarantee maintenance-free measurement. Specially designed mounting kits are also available.


  • Continuous and Real-time Measurement
  • 4 Sensors Measurement with One Controller Enables Economic Operation
  • Maximum 400 Days Data Logging and Monitoring
  • Wireless Option Avoids Cabling Cost
  • Automatic Sensor Cleaning Guarantee Maintenance-free Measurement
  • Built-in Unique Algorithm Eliminates Stationary and Moving Structures
  • Free WESSWARE Software Enables Field Data Analysis and Menu Setup


The ENV120 is designed to monitor the levels of solid contents (sludge) in various types of liquids (water, liquor, etc.), to control the pumps engaged in the processes, and to initiate events based on measured process conditions.


  • Water & wastewater treatment clarifiers
  • Water & wastewater gravity & DAF thickeners
  • Raw water clarifiers
  • Sumps, lagoons, settling ponds
  • Industrial process thickeners
  • Salt brine tanks
  • Material inventory tanks
  • Process thickeners


1. VARIOUS SCREENS: The instrument continuously provides the user with important information which includes numeric and graphic screens representing sludge level, current output, temperature, and an echo profile image to ensure correct configuration.


3. LIGHT SLUDGE LEVEL MEASUREMENT: The ENV120 is designed to measure not only heavy sludge (above 2,000mg/I) but light sludge at a drinking water sedimentation tank by selecting type of sludge from a menu section.

4. DATA ANALYSIS SOFTWARE: Free WESSWARE that can analyse the logged data and download the set parameters.

5. WIRELESS BLUETOOTH MODULE(WESS-RF): WESS-RF is a Bluetooth based wireless data communication system consisting of a master and a transmitter module. This system can be applied along with a controlling part of our measuring instruments such as ultrasonic sludge blanket level meter, density meter, level meter, etc. The WESS-RF system is normally used to reduce cabling cost and to apply where the bridge (walkway) moves. The WESS-RF offers not only mA output but also RS232 output. 



The swing bracket is to secure skimmer passage at clarifiers. Once it has passed, the bracket is free to fall, re-immersing the sensor into the clarifier water by a damper. The swing bracket is needed when the rotating skimmer hits a sensor. It has limited guarantee period since it’s mechanical device.


Periodical sensor cleaning is recommended as a precaution since floating debris and biological material are in contact with the ultrasonic sensor. The cleaning unit consists of a 10-meter length Ø6 air hose and an air compressor with terminal connection. The AC power source is given by a controller. For DC operation, additional power source or solenoid valve may be required for independent usage.


The standard cable length of sensor is 10m(33ft). To accept field requirements, the cable can be extended to 100m(330ft).


The blue-tooth based wireless module is needed where additional cabling costs is much higher than wireless network. The communication range is maximum 200m at an open field. Since transceiver module is mounted inside of a controller, no additional enclosure is required for outdoor installation. The WESS-RF offers not only analog output but also RS232 output.


We offers several types of mounting kits, such as sensor mounting kit, controller mounting kit, and cleaning unit mounting kit.


ENV120 provides RS232C digital communication as standard. RS485 and Profibus-DP are available as an option.



Do not inflict impact or unnecessary external force on the probe during handling. The ultrasonic head, which transmits and receives sound waves, should be handled with extra care and stored wrapped in sponge or other soft materials to absorb the impact of an external blow.

Attach and secure the probe using the 3/4” PF male thread located on the upper section of the probe. Pipe length selection should be based on the lowest liquid level. The pipe’s material should be chosen in consideration for material strength or application fluid characteristics. STS 304 20A, 10S pipe is the preferred choice in most applications. The cleaning air supply tube connects to the probe’s one- touch fitting only if the cleaning device is used.

Position the probe at a location where the ultrasonic signal from the bottom of the pool or tank is not blocked by surrounding structures (agitator, pipe, etc.). Additionally, to ensure stable measurement, the probe should be positioned away from air bubbles and active floating solids resulting from sudden changes in velocity. For tank or rectangular pool applications, maintain at least 1m of separation distance from the wall to minimize interference and try to avoid a hopper area where the shape of sludge blanket varies upon pumping activity.


Protect the controller from impact and unnecessary external force until it is installed. Install the controller on a panel/handrail or wall using the mounting holes (Φ 8) located at the back of controller. 

Located on the bottom of the controller are four cable glands the user can use selectively for his/her specific application. Each cable gland should be connected using a cable of correct diameter (Φ 4.5 ~ 10mm) to ensure IP67.

Most products generally use the direct cable connection method, in which stripped wires connect directly to a terminal block (TB). This makes for a difficult wiring process because of the sheer number of wires in a confined space.

ENV100, on the other hand, utilizes a new wiring method that uses an additional plug connector for the primary wiring and then it connects to TB stationed on PCB.



AC 100 to 240V, 50/60Hz, <6W. Use copper conductors only. A user-supplied disconnect switch on a separate 15A circuit breaker should be located near the processor unit. Power line noise and interference are filtered by a built-in EMI filter.


A 10m (33ft) of probe telemetry cable is supplied as standard. Contact your authorized distributor for extensions. The maximum length of cable extension is up to 100m (33ft) when authorized cable is in use.


The controller supports up to 5 parts of connections. Connections include Probe, mA and Serial Outputs, Relay Output, Cleaning Device, and Power. The controller accommodates up to 5 parts of connections.


Connect the five respective colored wires from the probe cable to a 5- position PHOENIX connector and then put it into the PCB board.


Serial communication (RS232/485) users may connect the serial wires to a 5-position PHOENIX connector and put it into the PCB board. The 5-position connector is composed of serial communication and analog output connections.


4 to 20mA current output users may connect the wires to a 5-position PHOENIX type connector and put it into the PCB Board.


Relay users may connect the wires to a 9-position PHOENIX type connector and put it into the PCB board.


The cleaning device is activated using the controller’s power source. Connection is made using a 2-position PHOENIX connector. Use AC power.


An external power source (100 to 240V, 50 to 60Hz) activates the ENV100. Connection is made using a 3-position PHOENIX connector. 

Technical Specifications Sheet

Please find a detailed Technical Specifications Sheet for this product by clicking the link below.


Please find the product manual by clicking the link below.