The wastewater was found to have a pH of 7.8. As mentioned in section 2.2, the wastewater used in this work was obtained from the slaughterhouse treatment plant after the step of chemical coagulation and prior to its aerobic biological treatment. This pH is optimum for the formation of the coagulant Fe(OH)3, according to reaction (10). During the water treatment, specifically in the coagulation step, FeCl3 and NaOH are added for the production of Fe(OH)3 as the main coagulant, resulting in the removal of a large amount of organics [50–52].