Raw water at this ground water supply well has iron concentrations above 0.7 mg/L.
The municipality was using sodium silicate to sequester the iron, however, coloured water complaints were occurring in parts of the distribution system where the hydraulic retention time was long enough for the iron to come out of solution.
Reviewed several treatment alternatives and the recommended solution was the implementation of biological iron removal using the Ferazur® filtration system which requires a tenth of the backwash water compared to greensand solutions and resulted in less discharge to the sanitary collection system.
This was the first installation of Ferazur® in Ontario.
Disinfection is accomplished through the use of chlorine gas and a baffled reservoir prior to discharge to the distribution system with high lift pumps.