Application of Natural Adsorbents for Heavy Metal Removal from Wastewater

<jats:p>Since 1995, intensive oil exploration and production activities have been carried out in the Tamsag and Dornogovi oil basins of Mongolia, with the produced crude oil being exported to China. These operations generate significant quantities of liquid wastes, including drilling fluids, well completion and testing fluids, service fluids, produced water, and wastewater from water injection treatment processes. Such wastewaters often contain petroleum hydrocarbons and heavy metals, posing considerable risks to soil quality and aquatic ecosystems. This study investigates the potential use of biochar derived from animal bone waste as a natural adsorbent for the removal of heavy metals from domestic and technological wastewater generated in oil fields. The bone-derived biochar was produced via pyrolysis at 500°C and subsequently subjected to chemical activation using sulfuric acid (H₂SO₄) and sodium hydroxide (NaOH) to enhance its adsorption properties. The adsorption performance was evaluated by measuring oil adsorption capacity, surface characteristics, and changes in heavy metal concentrations. The experimental results indicate that H₂SO₄-activated biochar exhibited the highest oil adsorption capacity (26.2%) and effectively reduced the concentrations of nickel (Ni) and chromium (Cr) in the wastewater. These findings demonstrate that biochar produced from animal bone waste can serve as an environmentally friendly and cost-effective natural adsorbent for treating liquid waste generated in the petroleum industry.</jats:p>