Advanced pretreatment technologies and natural anti-scaling approaches for enhancing reverse osmosis membrane performance in industrial wastewater treatment

Reverse osmosis (RO) membrane technology has emerged as one of the most efficient and reliable technologies for industrial wastewater treatment due to its high rejection efficiency for dissolved salts, heavy metals, pathogens, and organic pollutants. Despite its widespread industrial applications, membrane fouling and scaling remain major operational challenges limiting RO membrane efficiency, permeate quality, membrane lifespan, and economic sustainability. The increasing complexity of industrial effluents generated from textile, petrochemical, pharmaceutical, food processing, mining, and metallurgical industries has intensified the need for advanced pretreatment technologies and environmentally friendly anti-scaling strategies. This review critically evaluates recent advances in pretreatment technologies and natural anti-scaling approaches employed for enhancing RO membrane performance in industrial wastewater treatment systems. The review examines conventional and advanced pretreatment methods including coagulation-flocculation, adsorption, ultrafiltration, nanofiltration, dissolved air flotation, advanced oxidation processes, electrocoagulation, membrane bioreactors, and hybrid pretreatment systems. Furthermore, the study discusses membrane fouling mechanisms, types of scaling, and the operational factors influencing membrane deterioration. Special emphasis is placed on natural anti-scalants derived from biodegradable polymers, plant extracts, biopolymers, and green chemicals as sustainable alternatives to conventional synthetic antiscalants. The review also explores emerging technologies such as nanomaterial-enhanced membranes, smart membranes, and integrated membrane systems for improved fouling resistance and process sustainability. Findings from recent studies indicate that advanced pretreatment and natural anti-scaling strategies significantly improve permeate flux, salt rejection efficiency, membrane longevity, and overall process economics while reducing environmental impacts. The review concludes that sustainable pretreatment integration and green anti-scaling technologies represent promising pathways toward achieving efficient and environmentally responsible industrial wastewater management.