...to dry, and then set on fire prior to the cultivation of the soil and the planting of crops. Sludge A viscous, semisolid mixture of bacteria- and virus-laden...settled solids removed from domestic and industrial wastewater at sewage treatment plants. Smog A dense, discolored haze containing large quantities of...

...treatment by-product as fertilizer. The HarperCollins Dictionary of Environmental Science defines sludge as a viscous, semisolid mixture of bacteria and virus-laden...metals, synthetic organic chemicals, and settled solids. US researchers, cited in a Worldwatch Institute report and in the book Toxic Sludge Is Good for You,...