Journal
WATER RESEARCH
Volume 169, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.watres.2019.115207
Keywords
Low current; Phosphorus recovery; Local pH; Calcium phosphate; Electrochemical
Funding
- Dutch Ministry of Economic Affairs
- Ministry of Infrastructure and Environment
- European Union Regional Development Fund
- Province of Fryslan
- European Union [665874]
- research theme Resource Recovery
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Phosphorus removal and recovery from waste streams are crucial to prevent eutrophication and sustain fertilizer production. As has been shown in our previous papers, electrochemical treatment has the potential to achieve this goal. However, the adoption of electrochemical approach is limited by its high energy consumption. Here, we investigate the possibility of electrochemical phosphorus removal at extremely low current density using graphite felt as the cathode. We found a current density as low as 0.04 A/m(2) can enhance the removal of phosphate in our electrochemical system. The removal of phosphate at extremely low current density resulted from electrochemical induced calcium phosphate precipitation and not by electrochemical adsorption. Electrochemical treatment of real domestic wastewater at 0.2 A/m(2) almost eliminates the precipitation of Mg(OH)(2) and limits the formation of CaCO3. The recovered precipitates are dominated by calcium phosphate (59%), followed by 35% CaCO3 and 6% Mg(OH)(2). The specific energy consumption of this newly electrochemical system is between 4.4 and 26.4 kW h/kg P, which is 2 orders of magnitude lower than our previous system (110-2238 kW h/kg P). Key factors for this improvement prove to be enlarged precipitation area and hydroxide flux retardation by graphite felt. Practically, our study offers a potential way to reduce the energy consumption in electrochemical removal of phosphate by using a graphite felt cathode and at a current density below 0.2 A/m(2). Fundamentally, our study contributes to the understanding of adsorption and precipitation in electrochemical removal of phosphate at an extremely low current density and with carbon-based electrodes. (C) 2019 The Author(s). Published by Elsevier Ltd.
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