The ASLD2200 is supplied with a sensor that uses infrared attenuation as the principle of operation which allows Partech to ensure sufficient sensitivity to monitor sludge blankets in a wide variety of applications. It should be noted that sensor selection can be site dependent. Partech are happy to provide full support in the selection of the correct sensor.

The sensor will normally be positioned in the area of the tank just above the sludge and will therefore be kept away from the worst of the fouling that can occur in the treatment of either potable or dirty water. Provision must be made for transmission of the output signal to the control system; this is normally possible via spare slip rings. Where this is not possible a radio telemetry option is available, allowing transmission directly to the control system without the need for installation of cables.

When monitoring the Sludge Blanket Level in settlement tanks it is important to ensure that the sensor is sensitive enough to detect low density solids before ‘carry-over’ to the next process stage occurs, ensuring that potential pollution events are highlighted prior to occurrence. At the same time the sensor should not be ‘blinded’ by solids in the supernatant.

There is a choice of sensors for use with the ASLD2200, all the sensors use infrared attenuation as their operating principle, this makes them sufficiently sensitive for use on thin water treatment sludges as well as the more usual sewage treatment applications.