Design of a wastewater treatment clarifier

A. The "Wastewater Treatment Systems for Finishing Operations" chapter of the Organic Finishing issue of the Metal Finishing Guidebook has some good illustrations as a start. Key elements of a clarifier are:
- carefully dispersion at the inlets and carefully balanced sawtooth weirs so there are no short circuits, but rather the wastewater must very evenly and slowly flow upward, so that the floc can fall faster than the water rises;
- lamella plates or slant tube modules set at an angle of 55° or so, which allow the floc to touch a surface and agglomerate; - a good way to get the accumulated sludge out without disturbance.

The theory of lamella plates or slant tube modules is that if they are set at a proper angle, during the time that the water rises a foot, the floc only needs to fall only an inch or so before it will touch a solid surface and agglomerate, so you get settling equivalent to a tank 10 times as big. I've seen enough "clarifier upsets" to realize that it's not really the same thing as a tank 10x bigger, but lamella plates are more practical than a tank 10x as big :-)

For however long it remains online, the Metal Finishing Guidebook has some good illustrations and descriptions of metal finishing wastewater treatment equipment. Good luck.

A. Hi Neha. I haven't seen it, but it sounds like it might somewhat work since solids would not have to fall very far before they agglomerate on the plates and, hopefully, slide down them for faster settling. I'm not experienced with whether the plates would hinder the aeration process, but quite possibly not.

I've never personally seen lamella plates per se, as opposed to tube modules, in a round tank -- but I see no reason they would not be okay. The only thing is, the plates would probably have to be fairly short.

Regards,