The dairy industry is a major sector of the food processing industry and generates large volumes of wastewater due to extensive water usage during milk processing operations such as pasteurization, homogenization, equipment washing, and sanitation. It is estimated that 2.5–10 L of wastewater is produced per litre of milk processed. Dairy wastewater is characterized by high concentrations of organic and inorganic pollutants, including dissolved sugars, proteins, fats, sus-pended solids, total dissolved solids (TDS), and nutrients, resulting in elevated biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Improper disposal of such effluent can cause serious environmental pollution, odour nuisance, and ecological imbalance, necessitating sustainable treatment solutions. This study focuses on the biotechno-logical valorization of solid waste materials by converting waste dried guava leaves and coconut shells into granular activated carbon for dairy wastewater treatment. Synthetic dairy wastewater was prepared to simulate actual effluent characteristics and treated using the solid waste–derived adsorbents. The performance of the adsorbents was evaluated based on their ability to remove COD, BOD, and TDS. The experimental results demonstrated that both activated carbons effectively reduced pollution levels, highlighting their potential as sustainable and low-cost adsorbents. Activated carbon prepared from guava leaves achieved removal efficiencies of 76% for COD, 78% for BOD, and 65% for TDS, while coconut shell–derived activated carbon exhibited higher removal efficiencies of 84% for COD, 80% for BOD, and 68% for TDS. The comparative analysis indicates that valorized solid waste–based adsorbents can serve as efficient alternatives to conventional treatment materials. Overall, the study confirms that waste-to-resource conversion through biotechno-logical valorization offers an environmentally friendly and sustainable approach for effective treatment of dairy wastewater.

Dairy Wastewater, BOD, COD, TDS, Activated Carbon