关键词：斜发沸石；磷酸盐配体；水合氧化铁纳米颗粒；高分子材料
摘 要：Removal of two macronutrients, nitrogen (N) and phosphorus (P), from wastewater is critical before discharging the treated effluent to prevent eutrophication. But N and P are also essential components of any fertilizer; thus their recovery from wastewater will be an added bonus. This is especially critical for P since it is a non-renewable resource and its supply potential is getting diminished. For any process to have the ability to recover N and P from wastewater, it should be able to selectively remove the target ion containing N (NK_4~+_-N in this case) from a background of competing cations that may be present at a higher concentration (primarily Na~+ and Ca~(2+)) and the target ion containing P (H_2PO_4~- or HPO_4~2) which faces strong competition from competing anions such as Cl- and SO_4~(2-). Moreover, selective removal of NH_4~+_-N and P are not enough; the process should be efficiently able to desorb N and P to produce a small-volume, high concentration, regenerating solution. And finally, a solid-phase fertilizer of high purity should be extractable from the regenerating solution. On top of this, if the remaining regenerant solution can be reused in the next cycle, this process would be highly sustainable. Details of a process are provided where an inorganic zeolite (clinoptilolite) and a polymeric anion exchanger impregnated with iron oxide nanoparticles and preloaded with Cu as a selective ligand for phosphate are used to achieve selective N and P removal. The exchangers are efficiently regenerated with a combination of NaCl and NaOH and a solid-phase, high-purity fertilizer as MgNH_4PO_4 (struvite) is extracted. Three hybrid polymers were studied for P removal and recovery: HAIX, DOW-HFO, and DOW-HFO-Cu. Each material combines the durability, robustness, and ease-of-use of a polymeric ion-exchanger with the high sorption affinity of Hydrated Ferric Oxide (HFO) towards P. DOW-HFO-Cu was found to be the most efficient exchanger for removal of P. This was because both the HFO and the Cu, selective ligands for Cu sorption, acted in combination, thus providing maximum overall selectivity. The regenerating solution can be reused in the next cycle, thus creating a sustainable process with minimal waste effluent.