The Primary Settlement or sedimentation tanks are designed to reduce the velocity of the wastewater flow, allowing heavier organic solids (called raw sludge) to settle. They are the first stage of treatment after the removal of rags and grit in the inlet works. Scrapers present in the tank move continuously along the floor of the tank to deposit the raw sludge in hoppers for removal. The scum which floats to the surface is directed by water jets or scum boards to the sludge sump. The raw, settled sludge is removed by pump or gravity feed to a sludge treatment process, either on site or via tanker to a larger processing centre. Approximately 60% of suspended solids and 35% of BOD removal efficiency can be achieved at this stage.
The supernatant will still contain relatively high levels of suspend matter which will in most cases be passed on to some form of secondary treatment process. On sites where there is no secondary treatment discharge will be straight to the local watercourse. Monitoring of the suspended solids or turbidity level in the overflowing water is an important element of process control, both as a pollution prevention tool or as a dosing control parameter.
Monitoring the sludge blanket interface level allows automatic control of the de-sludging process ensuring that pumps are only used when required. This has the added benefit of producing better quality sludge for processing in digesters, thickeners and incinerators.
The SludgeWatch 715 provides a simple, low cost method of spot checking the sludge blanket level in a wide variety of settlement tanks
More DetailsThe SludgeWatch 8200w² Monitor provides a reliable method of detecting the sludge blanket level in clarifiers and settlement tanks.
More DetailsThe ASLD2200 is a fully automatic sludge blanket level detector designed for the water and waste water industry
More DetailsHighly sophisticated Sludge Blanket Monitor using an ultrasonic transducer to track the sludge blanket interface
More DetailsThe core product in the WaterWatch² range - the 7300w² Monitor provides all the user interface and system configuration
More DetailsInline Sensor for Sludge Density, Suspended Solids and Turbidity Monitoring
More DetailsDetecting the presence of the Sludge Blanket at a fixed level is one of the simplest ways of carrying out this control measurement
More DetailsContinuous monitoring of the sludge/water interface or sludge blanket is central to the efficient operation of clarifiers, thickeners and settlement tanks
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