Nanobiochar derived from organic waste: a sustainable solution for agriculture, environment, and circular bioeconomy

The rapid increase in organic waste generation, water contamination, and soil degradation presents major global environmental challenges. Conventional treatment methods, including activated carbon adsorption, chemical remediation, and bulk biochar application, are effective but often limited by high cost, low selectivity, and reduced efficiency for emerging contaminants. Nanobiochar has recently gained attention as an advanced alternative due to its enhanced physicochemical properties; however, a comprehensive understanding of its production, performance, and large-scale applicability remains limited. This review provides a systematic evaluation of nanobiochar derived from organic waste within the framework of sustainable resource management and circular bioeconomy. It examines production pathways involving pyrolysis followed by size reduction and surface modification techniques, including ball milling, sonication, and chemical treatment, along with key characterization approaches. Nanobiochar demonstrates significantly improved surface area (200–500 m2/g), porosity, and functional groups compared to conventional biochar, leading to enhanced adsorption capacity and reactivity. In wastewater treatment, removal efficiencies exceeding 90–99% have been reported for heavy metals and organic pollutants. In agricultural applications, nanobiochar improves soil fertility, nutrient retention, water holding capacity, microbial activity, and crop yield by 15–40%. Techno-economic analysis indicates that nanobiochar production is cost-effective ($500–1500/ton) and offers lower operational costs compared to conventional adsorbents, while contributing to carbon sequestration and waste valorization. Overall, nanobiochar is a promising multifunctional material; however, further research is required to address scalability, long-term environmental impacts, and regulatory challenges. Graphical abstract