In this study, MgO modified palygorskite (MgO-PAL) was successfully synthesized by co-precipitation method and was applied for enhanced and simultaneous recovery of nutrient from wastewater. All the results of this study indicated that MgO-PAL could be a highly effective, low-cost, non-second pollution and environmentally friendly material for simultaneous recovery of ammonia nitrogen and phosphate from wastewater through adsorption and in-situ struvite formation. The recovered product-struvite-palygorskite (S-PAL) was further reused as a novel phosphorus-bearing ameliorant for Cu, Pb and Cd immobilization in contaminated soil with three different rates (1%, 5% and 10% w/w). The metal extractability, metal fraction, immobilization mechanisms, bacterial community structure and metal release in amended soil upon acidification were separately carried out. The results indicated that the 0.01 mol/L CaCl2-extractability of metals significantly reduced with increasing rate of S-PAL in the first 7-day immobilization and insignificantly changed after 14-day immobilization. Compared with PAL, the lower metal extractability was observed after S-PAL addition. The BCR sequential extraction results showed that both of amendments were beneficial to transform acid soluble fraction to residual fraction. The XRD patterns of soil samples after immobilization evidenced that the formation of metal-bearing phosphate precipitates and the combination between functional groups such as Si-OH and metals played a key role for metal immobilization by S-PAL and PAL. Dominant phyla across all samples were Fusobacteria, Proteobacteria and Actinobacteria, and the relative abundance of Fusobacteria decreased under S-PAL treatment. The pH-dependent leaching test indicated that the metal release at a defined pH was not affected by the presence of PAL. Compared with S-PAL, the metals amended by PAL in soil were easier to release at acidic pH. Hence, our research enhanced the nutrient recovery from wastewater，and what’s more, the recycled products could not only be used as slow-release fertilizer, but also could be used as potential repair agents of heavy metal contamination in soil.

Application of struvite supported palygorskite derived by nutrient recovery from wastewater for in-situ immobilization of heavy metals in contaminated soil

256th National Meeting (2018)

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