Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 731, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2020.139002
Keywords
Potassium zeolite; Fly ash; Phosphate recovery; Treated wastewater; Sorption; Brushite
Categories
Funding
- Waste2Product project - Ministry of Science and Innovation (MINECO, Spain) [CTM2014-57302-R]
- R2MIT project - Ministry of Science and Innovation (MINECO, Spain) [CTM2017-85346-R]
- Excelencia Severo Ochoa Project - Ministry of Science and Innovation (MINECO, Spain) [CEX2018-000794-S]
- Catalan government [2017SGR312]
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The sorption of phosphate by K-zeolites synthesized from fly ash (FA) by hydrothermal conversion is investigated in this study. The aimis the synthesis of Ca bearing K-zeolites to recover phosphate from urban and industrial wastewater effluents. The loaded zeolites are considered as a by-products rich in essential nutrients such K and P (KP1) with a potential use as slow release fertilizer. A number of synthesis conditions (temperature, KOH solution/FA ratio, KOH concentration, and activation time) were applied on two FA samples (FA-TE and FA-LB) with similar glass content but different content of crystalline phases, to optimize the synthesis of a zeolitic sorbent suitable for the subsequent phosphate uptake. Merlinoite and W rich zeolitic products synthesized from FA-LB and FA-TE were found to have sorption properties for phosphate removal. A maximum phosphate sorption capacity of 250 mgP-PO4/g and 142 mgP-PO4/g for the zeolitic products selected (KP1-LB and KP1-TE, respectively) was achieved. The dominant phosphate sorptionmechanism, in the pH range (6-9) of treatedwastewater effluents, indicated that sorption proceeds via a diffusion-controlled process involving phosphate ions coupled with calcium supply dissolution from K-zeolitic products and subsequent formation of brushite (CaHPO4 2H(2)O (s)). The phosphate loaded sorbent containing a relatively soluble phosphate mineral is appropriate for its use as a synthetic slow release fertilizer. The simultaneous valorisation of fly ash waste and the P recovery from treated wastewaters effluents, (a nutrient with scarce natural resources and low supply) by obtaining a product with high potential for land restoration and agriculture will contribute to develop one example of circularity. (C) 2020 Elsevier B.V. All rights reserved.
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