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Hydrograv adapt System and Scraping Solutions

Reliable Technologies powered by our brand Passavant®

The aim of the primary and secondary clarification processes is to remove all floating and settleable solids, as far as possible, and to draw off clear water. Passavant-Geiger develops robust, low wear scraper technologies for the removal of sediments in circular and longitudinal tanks, which are suitable for a wide range of installation conditions and requirements.


Primary clarification is normally installed downstream of the grit removal and completes the inlet works / headworks. After biological processing, the water / sludge mixture is
separated in the secondary treatment process.
In order to separate the water from the solids, the wastewater is allowed to settle in sedimentation tanks so that the sludge is deposited on the tank bottom and the treated water can be drawn off via the launder channels. The sludge sediment is removed by means of scraper blades or suction pipes, whilst the floating matter is scraped from the surface of the water into an outlet channel. The scrapers move at a very low velocity, to avoid a renewed disturbance of the sediment from the bottom of the tank.
The cleaning process is supported in the grit traps by additional aeration systems which stir up floating matter and prevent organics from settling. As aeration alone is not sufficient, sand washers are then utilized to wash out the organics and ensure the separation of the organic content. The result: lower investment and operating costs which lead to a perceptible reduction in disposal costs.
Passavant-Geiger offers you durable low wear scraper systems for circular and longitudinal tanks with a tried and tested robust and reliable construction.