Activated nanosilica was used as an adsorbent and filter media for wastewater treatment in the dairy industry. Wastewater was analyzed for different physicochemical parameters (BOD, COD, Na, Ca, K, P, total nitrogen, and chloride) of dairy industry wastewater before and after treatment. According to the findings, the removal percentages of BOD, COD, Na, Ca, K, P, total nitrogen, and chloride were as follows: 82.612, 84.905, 90.225, 96.25, 66.12, 90.272, 90.78, and 87.013% for activated silica and 90.094, 86.77, 93.33, 66.12, 89.849, 90.66, 90.78, and 87.013% for nano silica, respectively.. Also, activated and nanosilica reduced turbidity with removal percents of 94.07 and 97.525%, respectively. Dissolved oxygen increased after treatment with activated silica and nanosilica, and activated silica increased pH to 9.2, while nanosilica decreased pH to 3.6.