Combined Phosphorus Removal and Recovery

The paper presents directions for a new system technology for municipal wastewater treatment, in order to consider both phosphorus removal and recovery. The system technology is proposed in a way to use as much as possible existing investments for the treatment and focus on modification of the operational mode. The process is based on removal followed by phosphorus recovery as calcium phosphates. In order to secure the biological phosphorus removal internal production of organic acids is necessary as the alternative to use acetic acid is costly. Chemically bound phosphorus may be released by combined thermal and acid treatment followed by phosphorus recovery. Introductory experiments indicate that leaching of phosphates from residues of supercritical water oxidation seem to be more easily dissolved than iron. It seems also to be easier to dissolve phosphate from the residue of supercritical water oxidation compared with leaching of ashes.