Sludge is a thick, viscous material that often results from industrial processes, wastewater treatment, or the breakdown of organic matter. It typically contains a mixture of water, solids, and various contaminants, making it a byproduct of activities like sewage treatment and oil refining. In environmental contexts, sludge can pose challenges for disposal and management. Proper treatment methods, such as dewatering and composting, are essential to reduce its volume and toxicity. When managed correctly, some types of sludge can be repurposed as fertilizers or energy sources, contributing to sustainable practices.