[Phosphorus adsorption and regeneration of electric arc furnace steel slag as wetland medium].
The long-term phosphorus (P) adsorption and retention capacities of electric arc furnace (EAF) steel slag materials derived from one batch and a 278-d column experiments with a synthetic P solution were compared. The investigations of the regeneration of the P adsorption capacity by water level decrease was conducted. It was revealed column experiment on a long-term basis can determine P saturation of EAF accurately. And the results can be used for realistic estimations of constructed wetland systems (CWS) longevity. EAF slag showed a high afinity for P, reaching a saturation value of 1.65 g/kg. Regeneration experiment of the P adsorbing capacity by this material showed that, after 4 weeks of water level decrease, EAF steel slag was able to increase its initial P adsorption capacity to 2.65 g/kg. A sequential P fractionation experiment was performed to quantify the proportion of P bound to mineral compounds in EAF. From the most loosely bound to the most strongly bound P fraction, P1 was associated with resin extractable (13%), Fe extractable (0.5 mol/L Na2CO3, 39%), Al extractable (0.1 mol/L NaOH, 21%), Ca extractable (1 mol/L HCl, 13%), and Ca in a stable residual pool (concentrated hot HCl, 14%). X-ray fluorescence analyses of EAF steel slag chemical composition revealed that the continuous application of a P solution resulted in 300% and 170% increases in K2O and P2O5, respectively. Al2O3 and FeO increased by 8%, while the portion of CaO remained unchanged. The investigated properties (P retention potential, regeneration of P adsorption, P fractionation) provide useful data about the suitability of slag material as a media for longterm P removal and dry-wet operation can improve P retention capacity of EAF to prolong the longevity of full-scale CWS.
Zhai
Li-hua
LH
Department of Environmental Sciences and Engineering, Tsinghua University, Beijing 100084, China. dilh03@mails.tsinghua.edu.cn
He
Lian-sheng
LS
Xi
Bei-dou
BD
Chen
Yue
Y
Meng
Rui
R
Huo
Shou-liang
SL
Liu
Hong-liang
HL
D000327:Adsorption; D007220:Industrial Waste / Q000032:analysis*; D010758:Phosphorus / Q000737:chemistry / Q000378:metabolism*; D013232:Steel / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D053833:Wetlands
D007220:Industrial Waste; D013232:Steel; D010758:Phosphorus