Study on functional modification of sludge ceramsite and treatment of wastewater containing phosphorus
With the rapid development of urban scale,the amount of municipal sewage treatment increases sharply,which leads to the disposal of sludge solid waste.The porous ceramsites(SC)were prepared with sludge as the main raw material and fly ash and montmorillonite as the auxiliary materials,and functionalized by co-precipitation method to obtain lanthanum modified sludge ceramsites(L-SC)and iron lanthanum modified sludge ceramsites(LF-SC).The pH,dosage and interference anion were the experimental factors to investigate the adsorption performance of phosphorus in simulated wastewater containing phosphorus,and the adsorption mechanism was discussed through analysis and characterization.The results showed that L-SC and LF-SC have dense pore structures with SBET of 17148.7 cm2/g and 17439.2 cm2/g,respectively.The adsorption performance of the modified ceramsite was significantly better than that of SC,and the phosphorus removal rate of L-SC was up to 93.74％at pH=5.However,the phosphorus removal rate of LF-SC is higher and the adsorption effect is less affected by pH,and the phosphorus removal rate is above 97％when 5≤pH≤9.Pseudo-second-order ki-netic model and Freundlich model can better describe the adsorption of phosphorus by modified ceramsites.The results of FTIR and SEM-EDS showed that transition metal Fe had obvious activation effect on rare earth metal La,which greatly improved the adsorption performance of the ceramsites.The main mechanism of phosphate adsorption was electrostatic attraction and ligand exchange to form stable complexes.
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