Valorisation of Silk Textile Industry Wastewater for Sustainable Agriculture: Life Cycle Assessment and Life Cycle Costing of Sericin Biostimulant Application in Lettuce Cultivation

The silk textile industry produces high volumes of wastewater during the degumming process, which removes sericin, a water-soluble protein coating raw silk fibres.Most of this sericin is currently lost in effluents, with limited reuse for cosmetics and biomedical solutions.Given the promising results of sericin in promoting seed germination, enhancing plant growth, and improving tolerance to abiotic stress, this study explores its novel agricultural application by assessing the recovery and reuse of sericin as a biostimulant in lettuce cultivation.Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) studies are conducted to evaluate the environmental and economic feasibility of three scenarios, using 1 kg of lettuce as the functional unit.The first scenario reflects the current system: wastewater is treated conventionally, and lettuce is grown using standard methods.In the second scenario, sericin is concentrated via ultrafiltration to a 5% w/v solution, then stabilised, diluted, transported, and applied to crops.The third scenario proposes a simplified route: the degumming wastewater is diluted and directly applied to the field, bypassing other processing steps.Findings reveal that the third scenario achieves the best results both in terms of environmental performance and economic viability, showing a 40% improvement over the second scenario on selected impact indicators.Sensitivity analysis confirms its benefits within a reasonable transport distance.Beyond replacing wastewater treatment, this approach converts a waste stream into an agricultural resource, aligning with circular economy principle The study also highlights the processes that contribute most to overall impacts and demonstrates the potential of sericin valorisation as a sustainable solution in the agricultural sector.