Pilgrim, E.1 and Smyth, M.2, 1Yorkshire Water, 2Aqua Enviro, UK
(free)Yorkshire Water installed 22 P schemes, with consents between 5 mg/l and 0.5 mg/l in AMP6.
AMP 7 will see around 80 new P permits of which at least 60 will include chemical dosing installations ranging from simple single-stage dosing to two-stage dosing with control philosophy and tertiary solids capture. For the majority of the AMP6 sites Iron (III) metal salt was chosen and where alkalinity was deemed a process risk, caustic dosing added. This paper describes operational experience, modifications and looks at data from selected sites to provide an overview of the molar ratios of chemicals used compared to design and predicts the levels of P that can be achieved thru single and twin point dosing. Challenges during commissioning, optimisation opportunities and benefit of good mixing are discussed.
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