text: The oil and gas industry uses media filters for various purposes in both upstream and downstream operations. Nut shell filters are commonly used as a tertiary oil removal step for treatment of produced water. Sand filters are often used to remove fine solids following biological treatment and clarification of oil refinery wastewater. Multi-media filters are used for removing suspended solids from both produced water and refinery wastewater. The materials commonly used in multi-media filters are gravel, sand, garnet, and anthracite.