To create raw materials with additional value, a range of raw materials from waste products from the mineral sector can be recycled. At the tertiary step of wastewater treatment, iron solid waste can be converted into inorganic coagulants. Steel waste can be converted into ferric chloride (FC) and poly ferric chloride (PFC), which are crucial for tertiary treatment of sewage water. The variables influencing the amount of FC and PFC were produced as (Fe2O3) were assessed, including pH, contact time, hydrochloric acid concentration %, and HCl flow rate. The generated FC and PFC were characterized using FTIR, XRD, XRF, and SEM as a new material that was later employed to treat wastewater. The highest removal percentage of turbidity, TSS, TOC, and TKN from tertiary treatment of sewage water with FC were, 92.7 %, 97.2 %, 88.2 %, and, 94.4 %, respectively. The highest removal percentage of turbidity, TSS, TOC, and TKN for tertiary treatment of sewage water were, 97.7 %, 98.4 %, 90.5 %, and, 96.8 %, respectively using PFC. In conclusion, FC and PFC made from steel waste should be used more widely in the tertiary treatment of sewage water, surface water, agricultural wastewater treatment since it is an affordable, high-quality coagulant and protection of environment.