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[Display omitted] • The maximum removal rate of residual lincomycin in LMRs was up to 98.38 % at 200 °C. • Protein and lignin/CRAMs compounds displayed the highest reactivity during AHT. • Humic acids were produced via a novel "Radicals-based polymerization" pathway. • Fatty acid and indole derivative were regarded as plant-growth-promoting compounds. Fermentation-based antibiotic production results in the generation of nutrient-rich antibiotic mycelial residues with significant recycling potential. However, the high concentration of residual antibiotics restricts their application in high-value contexts. This study employs an alkali-thermal humification treatment (AHT) to safely manage lincomycin mycelial residues (LMRs) and assesses the feasibility of the resulting LMRs liquid as organic fertilizer. The removal efficiency for lincomycin attains 98.38 % at 200 °C under AHT. Density functional theory calculations combined with liquid chromatography tandem mass spectrometry (LC-MS/MS) reveal that hydrothermal degradation of lincomycin occurs through processes such as hydrolyzation, N-demethylation, hydroxylation, and desulfurization. Post AHT, the LMRs liquid contains substantial quantities of amino acids (2.9 g/L) and humic acid (17.29 g/L) at 200 °C. Molecular networking identifies fatty acids and indole derivatives as plant-growth-promoting compounds in LMRs liquid, rendering it an appealing option for organic fertilization. Furthermore, a new pathway termed "Radicals-based polymerization" is proposed, which augments humic acid yield and organic stabilization. This study provides valuable insights into the comprehensive removal of antibiotics while concurrently recovering plant-growth-promoting compounds from antibiotic mycelial residues through the application of the AHT process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Non-targeted mass difference analysis was used to clarify DON transformation pathways. • Nucleic acid (mainly RNA) contributed to deamidization and deamination at 30 °C–70 °C. • Aspartyl, serine, histidine, and glutamyl units were representative precursors at 160 °C–200 °C. • HT liquor at 70–120 °C showed the highest DON bioavailability (∼57.6 %). Hydrothermal (HT) treatment has been considered effectively to recover nitrogen-containing organic nutrients from wastewater activated sludge (WAS), and understanding the fate and distribution of dissolved organic nitrogen (DON) during HT process is of great importance to process optimization. Thus, this study aims to investigate molecular transformation pathway of DON during HT process using non-targeted mass difference network analysis and evaluate the bioavailability of DON with chlorella. Results suggested that HT treatment was superior in N -containing organic matter solubilization (DON /TN > 60 %), and DON in WAS underwent extensive transformation processes at various HT temperatures. From room temperature to 70 °C, nucleic acids were solubilized to HT liquor, accomplishing with deamidation (–CONH + H 2 /H 2 O). And a representative ribose nucleic acid with a 'PA–pentose (ribose)–uracil (U)' structure was identified. With temperature rising to 120 °C, large amounts of stable protein were solubilized and hydrolyzed into HT liquor. The non-targeted mass difference network analysis suggested that, from 160 °C to 200 °C, aspartyl, serine, histidine, and glutamyl units were representative precursors for a variety of reactions including Maillard reactions, deamidation, deamination and so on. Amino acids were deaminated (–NH) to produce organic acids and ammonia (ammonium) or decarboxylated (–COO) to produce amines and CO 2. Dicarbonyl compounds (–C 2 H 2 O 2) were identified as the most abundant fragments which could either form humic substances or Maillard reaction products. Chlorella growth bioassay indicated that org-N in HT liquor produced at 120 °C showed the highest bioavailability for Chlorella , while that generated in HT liquor above 160 °C inhibited the growth of Chlorella. This study provided molecular insights for DON transformation following HT process and promoted high-quality resource utilization of WAS. [ABSTRACT FROM AUTHOR]