Microwave-alkali co-activated persulfate enables minute-scale fertilization of food waste with high fulvic-like acid yield

Food waste is a major global issue due to its large volume and rapid putrefaction. Although composting is a common recycling method, its long processing time (20-60 d) drives the need for more efficient fertilization technologies. This study demonstrates rapid humification of waste potato (WP), as a model food waste, into fulvic-like acid (FLA) fertilizer (15 wt% FLA and 7.6 wt% K+) using microwave-triggered KOH/persulfate (MW/KOH/PS) process. Under synergistic MW irradiation (180 W) and KOH (2 wt%), PS (2 wt%) is activated to generate •OH and •SO4-. This process simultaneously dissolves organic matter and elevates system temperature, inducing humification of organic components within 10 min. Compositional analyses revealed Maillard reactions and amidation during humification. Compared to KOH/PS, microwave intensification reduces chemical consumption by 75%, while achieving comparable FLA yields and significantly lowering cost by 62.4%. Pot experiments validates the plant-growth promotion and soil-amendment capabilities of the humified product. Scale-up trials confirm the efficacy for practical vegetable residues and cooked food waste. Unlike composting, this process completes in 10 min without requiring optimal C/N ratio or moisture content, exhibited only 20.1% carbon loss (WP system), and operates in scalable reactor, thus enabling same-day waste valorization into fertilizer. Significant amounts of food waste are generated, and although composting is a useful route for such waste, the process is long. Here, the authors report the development of a microwave-assisted method for the rapid humification of waste potato, resulting in a fluvic acid-like fertiliser.