Formula for estimating coagulant dose

[tipp79]

I've seen in a number of reports an equation to work out a theoretical ferric or alum dose for coagulation.

The formulas go something like this....

Alum Dose (as Al2(SO4)3.18H20) in mg/l = 17.8 + 0.295 x Colour (°H) + 5.41(pH - 7)

[Mean Turbidity + Mean Colour] x 0.08 x 2 x 3.6 = mg/l as Fe2(SO4)3

I know jar tests are the ultimate way to go, but having a theoretical way to estimate the dose is a useful thing to have at feasibility/outline design stages. Does anyone have a reference for these formula?

Thanks