This review summarizes the main species of polyphosphate accumulating organisms (PAOs) and algae, illustrates their pathways and key enzymes, discusses biological phosphorous (P) recovery from dilute waters, and identifies research avenues to encourage adoption and implementation. Phylogenic analysis indicates that the Proteobacteria phylum plays an important role in enhanced biological phosphorus removal (EBPR). The use of meta-transcriptome analysis and single cell-based techniques to help overcome the challenges associated with non-PAO competition was discussed. For algae capable of luxury phosphorus uptake, fundamental research is needed to illustrate the phosphorus regulation process and key proteins involved. Emerging technologies and processes have great potential to further advance phosphorus recovery, including combined PAO/algae reactors, bioelectrochemical systems, and biosorption by phosphorus binding proteins. As the paradigm shifts toward holistic resource recovery, research is needed to explore P+ recovery with other resources (e.g., metals from sludge), using a combination of biological and chemical approaches.

Phosphorus (P) is a critical, non-renewable nutrient; yet excess discharges can lead to eutrophication and deterioration of water quality. Thus, P removal from water must be coupled with P recovery to achieve sustainable P management. P-specific proteins provide a novel, promising approach to recover P from water. Bacterial phosphate-binding proteins (PBPs) are able to effectively remove phosphate, achieving extremely low levels in water (i.e. 0.015 mg-P L −1 ). A prerequisite of using PBP for P recovery, however, is not only removal, but also controlled P release, which has not yet been reported.Phosphate release using recombinant PBP-expressing Escherichia coli was explored in this study. Escherichia coli was genetically modified to overexpress PBP in the periplasmic space. The impacts of NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page. Letters, Vol. 363, No. 20 (October 2016). DOI. This article is © Oxford University Press and permission has been granted for this version to appear in e-Publications@Marquette. Oxford University Press does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Oxford University Press. FEMS Microbiology 2ionic strength, temperature and pH on phosphate release were assessed. PBP-expressed E. coli demonstrated consistently superior ability to adsorb more phosphate from liquid and release more phosphate under controlled conditions relative to negative controls (unexpressed PBP E. coli and E. coli K12). Lower pH (3.8), higher temperature (35ºC) and higher ionic strength (100 mM KCl) facilitated increased phosphate release, providing a maximum of 2.1% P recovery within 3 h. This study provides proof of concept of the feasibility of using PBP to recover P.