Ten State Standards

Ten State Standards:
The Ten State Standards website provides the following design parameters for coagulation and flocculation:
4.1.2     Coagulation
Coagulation shall mean a process using coagulant chemicals and mixing by which colloidal and suspended material are destabilized and agglomerated into settleable or filterable flocs, or both. The engineer shall submit the design basis for the velocity gradient (G value) selected, considering the chemicals to be added and water temperature, color and other related water quality parameters. For surface water plants using direct or conventional filtration, the use of a primary coagulant is required at all times

a.       Mixing – The detention period should not be more than thirty seconds with mixing equipment capable of imparting a minimum velocity gradient (G) of at least 750 fps/ft.   The design engineer should determine the appropriate G value and detention time through jar testing.

b.   Equipment   Basins should be equipped with devices capable of providing adequate mixing for all treatment flow rates.   Static mixing may be considered where the flow is relatively constant and will be high enough to maintain the necessary turbulence for complete chemical reactions.

c.   Location   The coagulation and flocculation basins shall be as close together as possible.

4.1.3     Flocculation

Flocculation shall mean a process to enhance agglomeration or collection of smaller floc particles into larger, more easily settleable or filterable particles through gentle stirring by hydraulic or mechanical means.

a.   Basin Design   Inlet and outlet design shall minimize short circuiting and destruction of floc. Series compartments are recommended to further minimize short-circuiting and to provide decreasing mixing energy with time.   Basins shall be designed so that individual basins may be isolated without disrupting plant operation. A drain and/or pumps shall be provided to handle dewatering and sludge...