Phosphorus removal performance and speciation in virgin and modified argon oxygen decarburisation slag designed for wastewater treatment

Abstract

Argon oxygen decarburisation (AOD) slag may be used for phosphorus (P) removal, as its high pH and weatherable calcium (Ca) minerals provide sufficient Ca 2+ and OH -for calcium phosphate (Ca-PO 4 ) precipitation.This study examined the P removal performance of AOD slag for use as wastewater treatment material. Batch experiments were carried out using both synthetic P solution and real wastewater, followed by chemical modelling and X-ray absorption near edge structure (XANES) spectroscopy. The influences of initial P concentration, slag dose and modification by polyethylene glycol (PEG), an effective agent for generation of 2 porous materials, were investigated to determine the optimal conditions for P removal by AOD slag. It was found that virgin AOD slag removed 94.8% of P from a synthetic P solution in 4 hours and 97.8% in 10 hours.This high P removal was accompanied by a rapid increase in pH from 7.0 to 10.74. The maximum P removal capacity (PRC) from synthetic P solution ranged from 1.3 to 27.5 mg P g -1 . The optimal AOD dose for P removal from wastewater, determined in 8-hour batch experiments, was 25 g L -1. PEG modification increased the reaction rate and resulted in higher final pH, increasing PRC by 47.9%. Combined Visual MINTEQ and XANES analysis for detailed examination of P removal mechanisms revealed that the main P removal mechanism was precipitation of calcium phosphate. According to the XANES analysis, the main Ca-PO 4 precipitate formed on virgin AOD slag under low initial P concentration and high pH was apatite, while brushite was the dominant product at high initial P concentration and low pH.

Phosphorus speciation in cultivated organic soils revealed by P K‐edge XANES spectroscopy

“…The spectra collected for the mineral soil layer in both profiles featured a shoulder at around 2157.5 eV. Additionally, two post‐edge peaks at 2164.7 eV and 2171.3 eV were present which in combination with the pre‐edge shoulder indicated the presence of calcium phosphates ( Zuo et al., ). Values of the goodness‐of‐fit factor R from the LCF analysis were in the lower range of those reported in previous studies ( Eveborn et al., ; Eriksson et al., ) (Tab.…”

The mechanisms of conventional pollutants adsorption by modified granular steel slag

“…Ca 2 Fe 9 O 13 , CaFe 4 O 7 , and CaSiO on the surface of GSS were easier to release Ca 2+ , which was beneficial to the precipitation in the reaction with phosphates, and improved the chemical adsorption capacity of GSS. The formation of Ca-P was largely depended on the dissolution of CaSiO 3 from GSS [27]. The width and strength of the peak of thermal modification also changed in various degrees, indicating that the high-temperature calcination changed the crystallinity of GSS.…”

“…Based on these theoretical studies, the adsorption capacity of steel slag was applied to the treatment of conventional pollutants, and great results had been achieved. Steel slag composed of calcium-rich oxides and silicates can be used for phosphorus removal and recovery from wastewater, because steel slag can provide sufficient Ca 2+ and OHfor the formation of calcium phosphate (Ca-PO 4 ) precipitates [17]. The removal efficiencies of ammonia nitrogen and total phosphorus could be improved apparently when the mass concentration of steel of 2.2-2.4 g/L were applied [18].…”

Study on Key Factors of Adsorption of Phosphorus by Steel Slag Filter Based on Response Surface Method

“…Minyu Zuo, et.al and Jianguo Li, et.al [10][11] used the response surface method to study the influence factors affecting the adsorption and dephosphorization performance of steel slag filter materials, and obtained the calcium content and initial pH value of the filter material. Both factors have a significant effect on phosphorus removal performance.…”