The circular recovery and reuse of nutrients from wastewater is vital for achieving sustainability goals and the EU Green Deal objectives.This study investigates the selective recovery of ammonium (NH) using a zeolitic tuff rich in chabazite as the main zeolite specie.We focused on targeting its applicability for farm-scale applications from different anaerobic digestates undergoing various pre-treatments (screw compression, microfiltration, and centrifugation).The obtained results were compared with another zeolitic tuff (rich in phillipsite and chabazite) from a previous study.The tested wastewaters included swine, cattle, and municipal solid waste digestates.Adsorption isotherms and kinetics were evaluated, considering key factors such as initial NH concentration, contact time, competing ions (e.g., K), total solids content, and pretreatment strategies.The adsorption process followed the Freundlich model, indicating heterogeneous multilayer sorption, while kinetic data aligned with pseudo-first-order and intraparticle diffusion models.NH removal efficiency showed an inverse correlation with K levels and solids content, with livestock-derived digestates enabling the highest nitrogen recovery per gram of zeolitic tuff due to their favorable composition and kinetics.Among the tested pre-treatments, centrifugation proved most effective, enhancing active site accessibility.A preliminary field-scale trial using microfiltered swine digestate at a 3% solid-to-liquid ratio demonstrated the feasibility of batch operation with an estimated nitrogen recovery of 715 kg N/year.This work lays the foundation for future comparisons with other zeolitic tuffs, such as those rich in clinoptilolite, and supports the principle of nutrient circularity in agriculture by reducing reliance on synthetic fertilizers.
Alberghini et al. (Mon,) studied this question.