Alum:Redox-Sensitive Phosphorus Ratio Considerations and Uncertainties in the Estimation of Alum Dosage to Control Sediment Phosphorus

Variations in the aluminum:phosphorus binding ratio and alum dosage considerations for Half Moon Lake, Wisconsin

“…Because sediment organic matter content was high (∼25%), this reaction was believed to be the outcome of coprecipitation between organic acids and Al at low pH (Cheng et al 2004). Nonetheless, others have shown that the mass of redox-P removed is equivalent to the mass of Al-P formed (Rydin and Welch 1999, James 2005, Pilgrim et al 2007). Redox-P bound by Al(OH) 3 was calculated as the difference between the initial and final redox-P concentration.…”

“…Various studies on Al dosage requirements to inactivate sediment P have reported Al:P binding ratios ranging from 2:1 to >100:1 (Rydin and Welch 1999, Rydin et al 2000, Lewandowski et al 2003, Reitzel et al 2003, 2005, James 2005, Dugopolski et al 2008. Under controlled experimental conditions with analytical grade phosphate (PO −3 4 ) and alum, P can bind to precipitated Al(OH) 3 at a molar ratio of ∼1:1 or slightly higher at neutral pH, depending on the initial PO −3 4 concentration and the extent of polymer formation (Lijklema 1980).…”

Lake and Reservoir Management

“…In an investigation where alum was used on experimental basis to remove P from the inflows of Fish and Tanners Lakes (USA), it was demonstrated that the treatment was effective in reducing long-term average TP concentration (Pilgrim and Brezonik, 2005a). In a continuing study, Pilgrim and Brezonik (2005b) (James, 2005).…”