Enhanced phosphorus removal using acid-treated magnesium slag particles

Area of Science:

• Environmental Chemistry
• Materials Science

Background:

• Magnesium slag particles (MSPs) are dual-purpose materials, serving as adsorption substrates and magnesium sources for struvite precipitation.
• Phosphorus removal from wastewater is crucial for preventing eutrophication.

Purpose of the Study:

• To investigate the effectiveness of hydrochloric acid (HCl) treatment in enhancing MSPs for phosphorus removal.
• To evaluate the impact of HCl treatment on MSP surface properties, adsorption capacity, and suitability as a magnesium source for struvite precipitation.

Main Methods:

• MSPs were treated with 1 mol/L HCl.
• Phosphorus adsorption was analyzed using adsorption models (Dubinin-Radushkevich, Langmuir, Freundlich).
• Magnesium ion (Mg2+) release and struvite precipitation were quantified.

Main Results:

• HCl treatment reduced MSP median diameter and increased specific surface area, boosting PO43- adsorption capacity by 188.96 mg/kg.
• The Dubinin-Radushkevich (D-R) model accurately described phosphorus adsorption (correlation coefficient > 0.94).
• HCl-treated MSPs provided a reliable Mg2+ source for struvite precipitation, achieving 53.63% PO43- removal under optimal conditions (pH 10.0, NH4+:PO43- ratio 1:1).
• Simultaneous adsorption and struvite precipitation in HCl-treated MSP solutions contributed significantly to overall PO43- removal (63.19%).

Conclusions:

• HCl treatment significantly enhances MSPs for phosphorus removal via improved adsorption and efficient Mg2+ supply for struvite precipitation.
• The combined approach of adsorption and struvite precipitation using HCl-treated MSPs offers a promising strategy for wastewater phosphorus management.