Radical-induced rapid humification of waste milk and the performance of derived slow release fulvic-like fertilizer

The direct disposal of waste milk (WM) leads to severe environmental pollution and resource loss. Considering the high content of nutrients, WM has a potential as an ideal raw material for organic fertilizer. In this work, base-activated persulfate (KOH/PS) was used as a new artificial humification technology to transform WM into product with 45.3% of fulvic-like acid (FLA) and 18.9% of humic-like acid (HLA) in 1 hour. Therein, FLA had more active groups (-COOH, -CNOH, -OH) than natural fulvic acid likely owing to hydroxylation, carboxylation and the Millard reaction. Reactive species of •OH and SO 4 − • generated in KOH/PS system may be related to degradation or polymerization reactions during humification. The product was mixed with attapulgite to fabricate a slow-release nano FLA fertilizer which could increase the yield of chickweeds by 107% compared with the blank as well as the abundance of beneficial bacteria in soil. Overall, this study provided a rapid method for the recycling of waste food and highly-concentrated organic wastewater, which may have a huge application prospect in sustainable agriculture.