Which one is the part of inorganic impurities of sewage?

Phosphates are an inorganic impurity in sewage.

Phosphates are a type of chemical compound that contains the mineral phosphorus, which is often used in fertilizers, detergents, and other industrial applications. In sewage, phosphates can come from a variety of sources, including household cleaning products, agricultural runoff, and industrial wastewater.

Unlike plant waste, which is an organic material, and human excreta and urea, which are organic compounds and obtained from plants and animal sources, phosphates are an inorganic substance. This means that they do not contain carbon-hydrogen bonds and are not derived from living organisms.