Adsorption of Phosphate in Aqueous Phase by Biochar Prepared from Sheep Manure and Modified by Oyster Shells

Sheep manure and oyster shells as C and Ca sources, respectively, were used to obtain Ca-enriched biochar materials with a high dephosphorization efficiency. This approach is helpful for the utilization of livestock manure and shell solid waste as well as for creating highly adsorbent materials. The results show that as the Ca content in biochar was increased, the material's phosphate adsorption capacity increased. The maximum adsorption efficiency reached 94%. The highest adsorption capacity (calculated using Langmuir fitting) of the material containing 1:1 biochar/oyster shell weight ratio reached 146.3 mg P/g. With the increase of the pH value of phosphate solution, the adsorption capacity of the sample gradually increased to 89.5-93.3 mg P/g. The adsorption occurred mainly by complexation. The results of this work provide insights into livestock manure and shell solid waste utilization, which yields a material with useful adsorption properties that can be applied for the removal of phosphate and other inorganics from water.