Optimization of a reactor for biostimulant production with emphasis on the economic aspects of hydrolysis

Abstract

Biostimulants are increasingly used in agriculture to promote plant growth, improve stress tolerance, and support sustainable farming practices. One common method of production is chemical hydrolysis of protein-rich waste, such as tannery by-products, offering an economical and eco-friendly alternative to conventional raw materials. This approach aligns with the principles of the circular economy by transforming industrial waste into valuable agricultural inputs. This study investigates the first stage of biostimulant production, alkaline hydrolysis at elevated temperatures, by analyzing the interplay between reaction kinetics, conversion efficiency, and operational costs. Through experimental data and kinetic modelling using a first-order reaction and the Arrhenius equation, key parameters such as activation energy and frequency factor were established. A techno-economic evaluation was conducted to determine optimal operating conditions, emphasizing the importance of the cost ratio between the reactor and evaporator. The results show that higher conversion rates and shorter reaction times are achievable with optimized temperature and cost parameters. Pilot-scale validation (100 L) confirmed process scalability, and preliminary field trials on maize demonstrated effects comparable to those of commercial products. These insights contribute to the advancement of scalable and cost-effective hydrolysis methods for producing biostimulants from waste protein sources.