A large compound formed of several orthophosphate molecules connected by phosphate-storing microorganisms.

Any of a broad familiy of inorganic phosphorus compounds that are commonly referred to as molecularly dehydrated phosphates or condensed phosphates, including hexametphosphate, tripolyphosphate (P3O105-), and pyrophosphate 2O7), among others. Unlike orthophosphate (PO43-), for which four oxygen atoms always surround a single central phosphate, polyphosphates are arranged as polymeric chains or occasionally rings that vary in their phosphorus-to-oxygen ratio and chain length with different commercial formulations. Polyphosphate is used as a sequestering agent to control iron and hardness, and as a coating agent that forms a thin passivating film on metal surfaces to control corrosion. Polyphosphates in solution are anionic and may be removed from water with anion exchange resins. However, polyphosphates that have reacted with a metal (e.g., iron) can form a sticky colloidal precipitate that must be filtered to be removed from water. Inorganic polyphosphates may tend to breakdown (hydrolyze) into orthophosphate groups plus molecules of shortened chain length over time and under extreme temperature and pH conditions. Upon breakdown these phosphate compounds can drop out any sequestered metal ions, such as iron and hardness, allowing them to precipitate from the water.

Polyphosphates are phosphate polymers linked between hydroxyl groups and hydrogen atoms. The polymerization that takes place is known as a condensation reaction. Phosphate chemical bonds are typically high-energy covalent bonds, which means that energy is available upon breaking such bonds in spontaneous or enzyme catalyzed reactions.

a salt or ester of polyphosphoric acid