Effect of carbon dioxide on phosphorus migration and transformation during sludge pyrolysis
The effect of carbon dioxide on phosphorus migration and transformation during sludge pyrolysis was investigated using municipal sewage sludge as raw material.The phosphorus accumulation in the sludge pyrolysis products was investigated by continuous graded phosphorus extraction(SMT),the crystal structure of the sludge pyrolysis products was determined by X-ray diffraction(XRD),and the bioavail-ability of phosphorus in the sludge pyrolysis products was evaluated by phosphorus bioavailability test.The results of the SMT showed that the reaction atmosphere played an important role above 700℃,and the at-mosphere of CO2 was more favorable to the enrichment and sequestration of phosphorus in the solid-phase products,which could promote the conversion of organic phosphorus(OP)to inorganic phosphorus(inor-ganic).XRD analysis showed that the main forms of NAIP in sludge were aluminum and iron phosphate,and the content of calcium and magnesium phosphate in CO2 atmosphere was higher than that in N2 at-mosphere at high temperature.The results of phosphorus bioavailability test showed that CO2 atmosphere had a more significant enhancement effect on the bioavailability of phosphorus,which showed the best bio-availability at 900℃and CO2 atmosphere,when the phosphorus solubility in 2%citric acid(CA)solu-tion reached a maximum of 80.77 mg/g,corresponding to the peak relative AP content of 23.31 mg/g.
sludgephosphoruscarbon dioxidepyrolysismigration of phosphorus
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