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Phosphate Recovery from Human Waste via the Formation of Hydroxyapatite during Electrochemical Wastewater Treatment

Cid, Clement A. and Jasper, Justin T. and Hoffmann, Michael R. (2018) Phosphate Recovery from Human Waste via the Formation of Hydroxyapatite during Electrochemical Wastewater Treatment. ACS Sustainable Chemistry & Engineering, 6 (3). pp. 3135-3142. ISSN 2168-0485. PMCID PMC5871340. doi:10.1021/acssuschemeng.7b03155.

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Electrolysis of toilet wastewater with TiO_2-coated semiconductor anodes and stainless steel cathodes is a potentially viable onsite sanitation solution in parts of the world without infrastructure for centralized wastewater treatment. In addition to treating toilet wastewater, pilot-scale and bench-scale experiments demonstrated that electrolysis can remove phosphate by cathodic precipitation as hydroxyapatite at no additional energy cost. Phosphate removal could be predicted based on initial phosphate and calcium concentrations, and up to 80% total phosphate removal was achieved. While calcium was critical for phosphate removal, magnesium and bicarbonate had only minor impacts on phosphate removal rates at concentrations typical of toilet wastewater. Optimal conditions for phosphate removal were 3 to 4 h treatment at about 5 mA cm^(–2) (∼3.4 V), with greater than 20 m^2 m^(–3) electrode surface area to reactor volume ratios. Pilot-scale systems are currently operated under similar conditions, suggesting that phosphate removal can be viewed as an ancillary benefit of electrochemical wastewater treatment, adding utility to the process without requiring additional energy inputs. Further value may be provided by designing reactors to recover precipitated hydroxyapatite for use as a low solubility phosphorus-rich fertilizer.

Item Type:Article
Related URLs:
URLURL TypeDescription Information CentralArticle
Cid, Clement A.0000-0002-7293-035X
Jasper, Justin T.0000-0002-2461-5283
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 2018 American Chemical Society. ACS AuthorChoice - This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. Received: September 7, 2017; Revised: February 1, 2018; Published: February 5, 2018. This research was supported by the Bill and Melinda Gates Foundation (Grants OPP 1069500 and OPP 1111246) and a Resnick Sustainability Postdoctoral Fellowship to J.T.J. C.A.C. and J.T.J. contributed equally to this work. The authors declare no competing financial interest.
Group:Resnick Sustainability Institute
Funding AgencyGrant Number
Bill and Melinda Gates FoundationOPP 1069500
Bill and Melinda Gates FoundationOPP 1111246
Resnick Sustainability InstituteUNSPECIFIED
Subject Keywords:Electrochemical precipitation, Phosphorus, Phosphate removal, Wastewater, Onsite sanitation
Issue or Number:3
PubMed Central ID:PMC5871340
Record Number:CaltechAUTHORS:20180215-163923294
Persistent URL:
Official Citation:Phosphate Recovery from Human Waste via the Formation of Hydroxyapatite during Electrochemical Wastewater Treatment. Clément A. Cid, Justin T. Jasper, and Michael R. Hoffmann ACS Sustainable Chemistry & Engineering 2018 6 (3), 3135-3142. DOI: 10.1021/acssuschemeng.7b03155
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84857
Deposited By: Clement Cid
Deposited On:21 Feb 2018 17:34
Last Modified:17 Mar 2022 17:19

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