Harnessing agricultural and agro-industrial waste for eco-friendly scale inhibitors: a review

Scale formation presents a continual problem across various industries. Its effects are diverse, encompassing substantial economic losses and health and safety hazards. Thus, the necessity to devise effective ways to address this situation is clear. Given the global shift towards a circular and sustainable bioeconomy and the principles of green chemistry, the utilization of eco-friendly scale inhibitors is garnering increasing attention in both scientific and industrial domains. Agricultural and agro-industrial waste emerges as a promising source of active compounds, which can be extracted using simple, cost-effective processes. Recently, several studies have been published documenting the potential of waste as a source of green scale inhibitor in all scale forms (i.e. CaCO₃, CaSO₄, BaSO₄, etc.). Their mode of action is based on several mechanisms including inhibition of nucleation, modification of crystal morphology, and particle dispersion. However, despite their potential, the use of these wastes as scale inhibitors presents challenges, notably linked to the variability of their composition and the constraints of large-scale applications. However, a systematic review linking the variability in agricultural waste composition, its scale inhibition mechanisms, and its feasibility for industrial application is still lacking. This review aims to fill that gap. This document will be a valuable reference for researchers and industrialists engaged in the development of sustainable, cost-effective processes for scaling control and waste management.