A sustainable approach for water management and nutrient recovery

As the global population continues to rise, water reservoirs are encountering increasing threats, amplifying concerns regarding environmental degradation and the scarcity of freshwater resources. This study investigated the potential of hydrochar (HC) generated from apricot kernel shells (AKSs) through the process of hydrothermal carbonization (HTC) as a solution to these challenges. It comprehensively analyzed the relationship between HTC parameters, specifically temperature and duration, and the resulting HC properties, including water-holding capacity (WHC), electrical conductivity, pH, and ion adsorption capabilities. The hydrochar sample (HC₁₂), treated at 240 °C for 120 min in the initial run, demonstrated a superior water-holding capacity (WHC) of 4 g/g, making it promising for moisture conservation in tropical climates. Additionally, the hydrochar sample (HC₁) showed a high yield (69.39 W%, 30 min, and 150 °C), indicating efficient biomass conversion. In subsequent runs, the sixth hydrochar sample (HC₆) exhibited significant NH₄⁺-N adsorption (37.33 ± 0.01 mg/g), while the second hydrochar sample (HC₂), treated for 60 min, achieved the highest PO₄^3--P sequestration (5.89 ± 0.21 mg/g). Despite the potential of hydrochar in moisture conservation, biomass yield, and NH₄⁺-N sequestration, further optimization is essential for effective PO₄^3--P recovery. This research highlights the extensive potential of hydrochar derived from apricot kernel shells via hydrothermal carbonization, presenting innovative solutions for sustainable water management, soil enrichment, and agricultural advancements.