Abstract
<jats:p>Spent industrial zeolite adsorbents from gas drying, hydrocarbon purification and molecular-sieve separation units represent a mineral waste stream with potential value for sustainable soil management. This study develops a product-specific circular route for converting CaA-, NaA- and KA-type spent zeolites into three soil-improving products: ZeoMeliorant-CaA for saline and compacted soils, ZeoModifier-NaA/KA for nutrient retention in cultivated and greenhouse soils, and ZeoSubstrate-15 for peat-based growing media. The proposed route combines mechanical preparation, thermal regeneration at 530–550 °C, optional microwave activation, mild citric-acid modification, washing, drying and fractionation. The manuscript also establishes a soil-testing matrix and safety-control criteria for agricultural use. Preliminary model-based assessment indicates that properly regenerated zeolite products may improve water-holding capacity, cation-exchange performance and biological response while reducing salinity-related stress when the dose and target medium are correctly selected. FTIR and XRD characterization are used to verify removal of organic residues, surface modification and preservation of the A-type/LTA aluminosilicate framework. The approach links industrial adsorbent waste management with soil melioration, nutrient retention and substrate improvement, but final agronomic validation requires measured XRF/ICP, FTIR, XRD, pH, EC, CEC, residual hydrocarbon, heavy-metal, germination and pot-trial data.</jats:p>