Phosphate Removal from Swine Waste Waterwith Unburned Red Mud Ceramsite

Abstract

Red mud, a waste tailing from the alumina industry, was calcined at different temperatures. The calcined red mud was used to prepare the unburned ceramsite as adsorbent to remove phosphate from the effluent of swine waste water treated with a sequencing batch reactor (SBR). Adsorption of phosphate to the unburned ceramsite made of raw red mud and activated red mud was studied as a function of dosage, pH and reaction time. The adsorption of phosphate to the red mud unburned ceramsite both in-roasting and roasting fit the Langmuir isotherm. Calcination of red mud enhanced the adsorption capacity of unburned ceramsite greatly. The pH has an obvious effect on the removal and high pH favors the removal of phosphate. The adsorption mechanism is suggested to include surface complexation reactions, and the mechanism of phosphate removal may include co-precipitation. Due to their low cost and high capability, it is concluded that the red mud unburned ceramsite may be an efficient adsorbent to remove phosphate from swine waste water.