Calcium Carbonate Packed Electrochemical Precipitation Column: New Concept of Phosphate Removal and Recovery

Phosphorus (P) is a vital micronutrient element for all life forms. Typically, P can be extracted from phosphate rock. Unfortunately, the phosphate rock is a nonrenewable resource with a limited reserve on the earth. High levels of P discharged to water bodies lead to eutrophication. Therefore, P ne...

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Bibliographic Details
Published in:Environmental science & technology 2019-09, Vol.53 (18), p.10774-10780
Main Authors: Lei, Yang, Narsing, Santosh, Saakes, Michel, van der Weijden, Renata D, Buisman, Cees J. N
Format: Article
Language:English
Subjects:
Calcium
Calcium buffering
Calcium carbonate
Calcium ions
Calcium phosphates
Chemical precipitation
Continuous flow
Electrochemistry
Eutrophication
Feed rate
Flow system
Hydraulic retention time
Nonrenewable resources
Particle size
Phosphate
Phosphorus
Phosphorus removal
Recovery
Retention time
Rocks
Seeds
Streams
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Summary:Phosphorus (P) is a vital micronutrient element for all life forms. Typically, P can be extracted from phosphate rock. Unfortunately, the phosphate rock is a nonrenewable resource with a limited reserve on the earth. High levels of P discharged to water bodies lead to eutrophication. Therefore, P needs to be removed and is preferably recovered as an additional P source. A possible way to achieve this goal is by electrochemically induced phosphate precipitation with coexisting calcium ions. Here, we report a new concept of phosphate removal and recovery, namely a CaCO3 packed electrochemical precipitation column, which achieved improved removal efficiency, shortened hydraulic retention time, and substantially enhanced stability, compared with our previous electrochemical system. The concept is based on the introduction of CaCO3 particles, which facilitates calcium phosphate precipitation by buffering the formed H+ at the anode, releases Ca2+, acts as seeds, and establishes a high pH environment in the bulk solution in addition to that in the vicinity of the cathode. It was found that the applied current, the CaCO3 particle size, and the feed rate affect the removal of phosphate. Under optimized conditions (particle size, 50% removal over 125 days with little maintenance. The specific energy consumptions of this system lie between 29 and 61 kWh/kg P. The experimental results demonstrate the promising potential of the CaCO3 packed electrochemical precipitation column for P removal and recovery from P-containing streams.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.9b03795