Water treatment residuals are the by-product from drinking water purification plants. Chemicals are added to raw water to remove organic matter, sediments, and other unwanted compounds. The resultant residuals often have a consistency similar to jello. These residuals are sometime treated with lime to make them easier to handle.
Water treatment residuals that are lime treated can be used agriculturally as a lime. Other water treatment residuals are sometimes used to bind phosphorus at the soil surface and prevent it from moving into surface water.