Electrochemical removal of phosphate in the presence of calcium at low current density: Precipitation or adsorption?

Yang Lei*, Emilio Geraets, Michel Saakes, Renata D. van der Weijden, Cees J.N. Buisman

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

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/m2 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/m2 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/m2. 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.

Original languageEnglish
Article number115207
JournalWater Research
Volume169
DOIs
Publication statusPublished - 1 Feb 2020

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density current
Calcium
Phosphates
Current density
calcium
phosphate
adsorption
Adsorption
graphite
Graphite
Energy utilization
Calcium phosphate
Phosphorus
Cathodes
phosphorus
Eutrophication
Fertilizers
hydroxide
removal
eutrophication

Keywords

  • Calcium phosphate
  • Electrochemical
  • Local pH
  • Low current
  • Phosphorus recovery

Cite this

@article{3f42c9cd4cdd45a8862b5a519439896c,
title = "Electrochemical removal of phosphate in the presence of calcium at low current density: Precipitation or adsorption?",
abstract = "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/m2 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/m2 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/m2. 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.",
keywords = "Calcium phosphate, Electrochemical, Local pH, Low current, Phosphorus recovery",
author = "Yang Lei and Emilio Geraets and Michel Saakes and {van der Weijden}, {Renata D.} and Buisman, {Cees J.N.}",
year = "2020",
month = "2",
day = "1",
doi = "10.1016/j.watres.2019.115207",
language = "English",
volume = "169",
journal = "Water Research",
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}

Electrochemical removal of phosphate in the presence of calcium at low current density: Precipitation or adsorption? / Lei, Yang; Geraets, Emilio; Saakes, Michel; van der Weijden, Renata D.; Buisman, Cees J.N.

In: Water Research, Vol. 169, 115207, 01.02.2020.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Electrochemical removal of phosphate in the presence of calcium at low current density: Precipitation or adsorption?

AU - Lei, Yang

AU - Geraets, Emilio

AU - Saakes, Michel

AU - van der Weijden, Renata D.

AU - Buisman, Cees J.N.

PY - 2020/2/1

Y1 - 2020/2/1

N2 - 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/m2 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/m2 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/m2. 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.

AB - 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/m2 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/m2 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/m2. 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.

KW - Calcium phosphate

KW - Electrochemical

KW - Local pH

KW - Low current

KW - Phosphorus recovery

U2 - 10.1016/j.watres.2019.115207

DO - 10.1016/j.watres.2019.115207

M3 - Article

VL - 169

JO - Water Research

JF - Water Research

SN - 0043-1354

M1 - 115207

ER -