Poly-Aluminium Choride (PAC) is considered as an effective combined coagulant and precipitating agent, which can recombine dissolved substances. With PACs different types of suspended particles can be eliminated from liquids.

It has the general formulation of Aln(OH)mCl3n-m

The PAC process is very corrosive due to the usage of Aluminum hydroxide. It is intensively mixed in the reactor with hydrochloric acid and settled by a relatively high temperature (180°C ) and increased pressure (8 bar) under water formation to PAC. By adding conditioners the chemical composition the final PAC product can be optimized and adapted for a specific application.