Automatic Sludge Blanket Level Detector Online Brochure
Markland Detectors help municipal/industrial water & wastewater plants measure, monitor and control silt/sludge interface levels in clarifiers and settlement tanks, and automate sludge removal. By increasing process effectiveness and efficiency, it benefits both the specific application and the broader environmental setting.
The Detector uses high-intensity infrared light beams to help monitor interface levels in clarifiers and settlement tanks (including lamellas, dissolved air flotation thickeners, decanting tanks, sequencing batch reactors, upflow filter reactors and sedimentation basins), when treating raw or waste water. It measures primary and secondary sludge, as well as backwash sludge from sand/membrane filters, resin beds in intake water softeners, settled mud levels in tanks and settled fly ash from scrubbers.
This detector allows users to program sludge removal pumps to operate only when necessary: preventing carryover; avoiding pumping thin sludge or large volumes of water (when a core hole is pulled); optimizing feed density for improved filter press/centrifuge/digester performance, and improving the quality and quantity of water available for reuse. In addition, features are uniquely suited for specific applications. For example, in DAF units, the detector can adjust the speed of the surface skimmer to match changes in the thickness of the floating sludge layer; in SBRs, it can control the decant valve, enabling cycle time to be kept to a minimum. Eliminating unnecessary pumping reduces wear-and-tear on pumps, downtime for maintenance, and energy usage.
The detector (4- and 8-foot models are available) uses a vertical probe submerged in the tank. Sixty-four LEDs are placed within a gap running the length of the probe. Each shines across this gap to a matching phototransistor sensor. These pairs are sequentially scanned to locate the settled bed. Beam power intensity automatically adjusts to accommodate different sludge and overlying liquid concentrations. The slim profile, with lights and sensors contained within the probe gap, make it well suited for obstructed or constricted areas; for example, the curved walls of lamellas do not affect readings. The probe is placed at a height that enables the operator to maintain a desired sludge bed depth (often offset from the bottom of the tank). When the sludge level reaches the preferred maximum height, the detector sends a signal to the control system or computer to trigger the de-sludge pump to turn on. When the ideal minimum sludge level is met, an output signal turns the pump off. The all-PVC probe is corrosion-free. Analog and relay outputs are available. No calibration is required with this simple-to-install detector. A wireless data link is available as an optional feature or upgrade.