Eco-Friendly Multistage Treatment of Dairy Wastewater Using Natural Coagulants: Mechanisms, Performance Evaluation, and Future Perspectives-A Review

The dairy industry is one of the major agro-based sectors contributing significantly to global wastewater generation. Dairy effluent is characterized by high concentrations of organic matter, suspended solids, fats, and nutrients, resulting in elevated biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Conventional treatment methods using chemical coagulants such as alum and ferric salts are widely employed; however, these methods are associated with drawbacks including high sludge production, residual toxicity, and increased operational costs. In recent years, natural coagulants derived from plant-based materials, biopolymers, and agro-wastes have emerged as sustainable alternatives due to their biodegradability, low toxicity, and economic feasibility. This review critically examines the characteristics of dairy wastewater, mechanisms of coagulation, and the performance of various natural coagulants. Furthermore, their integration into multistage treatment systems and future prospects for large-scale applications are discussed, highlighting their potential for sustainable wastewater management.

Dairy wastewater, natural coagulants, sustainable treatment, coagulation-flocculation, eco-friendly wastewater management

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