The document discusses the defluoridation of water using activated coffee husk and activated tea waste. It examines the effect of varying pH, contact time, adsorbent dosage, and initial fluoride concentration on the adsorption efficiency of these materials. For activated coffee husk, the maximum removal efficiency of 86.32% was achieved at pH 10, contact time of 180 minutes, adsorbent dosage of 10g, and initial fluoride concentration of 10mg/L. For activated tea waste, the maximum removal efficiency of 96.89% occurred at pH 2, contact time of 60 minutes, adsorbent dosage of 1g, and initial concentration of 10mg/L. Both materials showed good potential as