Phosphorus recovery from sewage sludge using the Aquacritox supercritical water oxidation process
O’Callaghan,P.1 and O’Regan, J,2 , 1O2 Environmental, Ireland, 2 SCFI, Ireland
(free)
Phosphorous is typically present in two forms with in sewage sludge, intracellular as present in activated sludge and as precipitated phosphorous as the result of the addition of a chemical precipitant..
Aqua Critox® scwo is an innovative and effective process for the destruction of the organic fraction of sewage sludge. All liquid and solid fractions exiting the Aqua Critox® process are free of organics and sterile. This creates the ideal conditions for simple and effective recovery of the phosphorous that is present in the sewage sludge.
The Aqua Critox® process releases the entire intercellular phosphorous bound with in the activated sludge which will exit the Aqua Critox® process as a phosphate salt solution that is easily recovered as a pure phosphate salt or phosphoric acid.
Phosphate present in the sewage sludge as precipitated phosphate such as ferric phosphate or aluminium phosphate will exit the Aqua Critox® process as an inert organic free fraction which can through simple wet chemistry be recovered as a phosphate salt.
The recovery process will also yield full recovery of the coagulant/ precipitant for reuse with in the plant.
Phosphate recovered from the Aqua Critox® process is a high grade material that can have significant market value and is not dependent on agricultural demand.
