What goes down your toilet can end up on farm fields across the United States. Biosolids, or sewage sludge, are the solid byproducts of the wastewater treatment process. Rich in nutrients, they can be ...

The oil inside your car's engine can sludge up with neglect and infrequent oil changes. Sludge is a nasty contaminant that can destroy an engine if not given attention, but timely oil changes are a ...

Using sewage sludge – one of two end products from any wastewater treatment plant (the other is effluent) – as fertilizer on food crops is a hotly debated food safety issue, but only among a very ...