Ultrafiltered RC closely tracks the performance of FFS, removing 81% and 74% of P at a sludge pH of 2, respectively. This similarity was due to the exclusion of insoluble Fe from the sludge as well as 50% DOC removal by the ultrafiltration membrane (Keeley et al.,2014a).
When dosed, normalised to total Fe, this ensured similar Fe availability and minimal interference from organic compounds (Wang et al., 2012). P removals with FFS and ultrafiltered RC remained unchanged from pH 4.5 to 3 but removed a further
1.5 mg/L P as the pH was lowered to 2.