In order to remove flocks, containing the most part of suspended solids, a clarifier is necessary.
Water containing sludge flocks created into the coagulation-flocculation tank, reaches the clarifier by gravity, where, because of the difference of specific weight, are clearing on the bottom of the tank. The clarifier is a tank that, in particular conditions of quietness, allows the settlement of the sludge flocks with a consequently good separation between clean water and flocks of sludge.
The sludge settled on the bottom is collected by a scraper and convoyed towards the centre of clarifier, where by means of a pipe it is sent outside of the sedimentator towards the sump .
Inside of the clarifier, water will be separated from the sludge flocks, that means clarified.
Lamellar packs are a sequence of wavy lamella, located one parallel to the other inside a frame and collected inside a tank.
In order to guarantee a good sedimentation of solids, lamella are inclined in order to have a 60° angle with the horizontal floor.
When the waste water flow goes through the lamellar pack, every solid particles aggregate to each other thanks to a circular movement in the initial part of the lamella.
Due to gravity all the particles settled over the lamella surface fall to the tank bottom that is called clarifier. In this point solids will set in layers increasing their thickness in order to be later extracted through the sludge line.