An experimental laboratory was conducted to treat produced water by kapok fiber adsorbent, activated using sodium hydroxide (NaOH) 5% wt. and hot water at 100 oC followed by ultrafiltration membrane to reduce total dissolved solids (TDS), barium, and phenol concentration. The research variables were operating times of 30, 60, and 90 min, and the flow rate of produced water samples was 5 L/min, …