Iris kashmiriana Rhizome as a Novel Biocoagulant for Sustainable Sewage Treatment Driven by PIMT-Net Guided Optimization

17 Industrialization demands sustainable wastewater treatment approaches to reduce the 18 environmental impact of chemical coagulants.This study reports the first application of 19 Iris kashmiriana rhizome as a high-performance biocoagulant for sewage treatment plant (STP) 20 effluent, integrating experimental validation with a Physics-Informed Multi-Task Transformer 21 Network (PIMT-Net) and identifying isoflavone-rich phytochemicals as the primary coagulation-22 active constituents.Baseline characterization revealed that BOD 5 (82.0 mg L⁻¹), COD (278.0 mg 23 L⁻¹), and TSS (225.0 mg L⁻¹) exceeded safety standards, highlighting necessity for remediation 24 through this novel biocoagulant.Jar test optimization demonstrated that a 1% Iris 25 kashmiriana rhizome extract at an Optimum Economic Dose (OED) of 5.0 mL L⁻¹ reduced 26 turbidity from 176.0 to 26.0 NTU (85.2% removal).The primary mechanism was identified as 27 charge neutralization, although overdosing (10-25 mL L⁻¹) induced steric restabilization.28 Advanced characterization (SEM-EDX, FTIR and SHAP-based interpretation) revealed a carbon-29 rich composition and a synergistic mechanism involving zeta-potential neutralization (ζ: -28.4 to 30 -3.8 mV), Ca 2⁺ ion patching and polymeric bridging.The system exhibited strong Adsorption 31 behaviour (R² = 0.9840; n = 1.8720;K F = 5.0), confirming Freundlich multilayer adsorption on a 32 heterogeneous surface, described by the empirical relation: qₑ = 5.0000•Cₑ0.5342.Thermodynamic 33 analysis confirmed that the process was spontaneous (ΔG° = -19.87kJ mol⁻¹), and exothermic 34 (ΔH° = -14.22kJ mol⁻¹).Kinetics studies showed rapid adsorption (k a = 0.0637 min⁻) and 35 X-DLVO analysis revealed strong attractive forces (V total = -31.9kBT).The implementation of 36 Physico-Informed Multi-Task Transformer Network (PIMT-Net) enabled accurate prediction of 37 OED (5.0 ml L⁻¹) achieving minimal sludge yield (0.041 g L⁻¹) and a favorable operating cost ( 38 0.456 USD ⋅ m -3 ).These findings demonstrate that the Iris kashmiriana rhizome as a scalable, 39 sustainable and high performance biocoagulant for decentralized circular wastewater systems.