Circular Economy in Bricks: Resource, Water, and Energy Savings via Refinery Oily Sludge.

Conventional clay brick manufacturing is highly resource-intensive, relying on virgin clay, large volumes of process water, and high fossil-fuel-driven firing temperatures (900-1200 °C), posing significant environmental pressures. This study introduces a methodological innovation by valorizing refinery oily sludge (ROS), a hazardous petroleum byproduct, to achieve simultaneous reductions in raw material, water, and energy consumption. Clay mixtures containing 0, 5, and 10 wt % ROS were extruded and fired at 950 and 1050 °C. The optimal 5 wt % ROS substitution reduced process water demand by 25% and firing energy consumption by over 30%, while nearly doubling brick production yield from 5.6 to 9.5 units/kg of clay. Minor color changes and efflorescence were observed, but the mechanical integrity remained unaffected. These findings demonstrate a scalable pathway for the ceramic industry to transform hazardous waste into a valuable resource, achieving integrated environmental and resource savings in line with circular economy and sustainability principles.