Eficiência de coagulantes orgânicos e hidroxiapatita no tratamento de efluentes de frigorífico de suínos

Abstract

Pork is widely consumed in global cuisine, which drives its large-scale production. However, swine slaughterhouses generate large volumes of effluents with high concentrations of organic matter, chemical oxygen demand (COD), turbidity, color, nitrogen, copper, and zinc—pollutants that require treatment before being discharged into water bodies. The physicochemical treatment, using coagulants, is an effective conventional method for removing these pollutants. Inorganic coagulants are widely used, but organic coagulants, such as green coconut husk, Moringa oleifera seeds, and tannin (Tanfloc), have gained attention due to the biodegradability of the generated sludge and the lower production of metallic waste. The objective of this study was to evaluate the efficiency of these coagulants in removing pollutants from swine slaughterhouse effluents and to investigate the use of green coconut combined with other coagulants for nitrogen removal. Additionally, the removal of heavy metals with synthetic hydroxyapatite and hydroxyapatite derived from fish bones was assessed. In Step 1, the coagulants achieved nitrogen removal rates below 10%, with aluminum sulfate increasing nitrogen concentrations. For turbidity, all coagulants removed more than 80%, with aluminum sulfate reaching 87%. Color removal was above 79%, with aluminum sulfate achieving 84.76%. In COD removal, the organic coagulants stood out, with tannin removing 59.47%. In Step 2, with the addition of green coconut, only green coconut and Tanfloc + green coconut managed to remove 8% of the nitrogen. For turbidity and color, removal rates were above 80% and 76%, respectively. COD removal exceeded 44%, but the efficiency of green coconut was variable, impairing the performance of other coagulants in some cases. In Step 3, synthetic hydroxyapatite was slightly superior to fish bone-derived hydroxyapatite, but copper and zinc removal remained below 10%. It is concluded that the use of organic coagulants is promising for the treatment of swine slaughterhouse effluents. However, the combination with green coconut requires adjustments to optimize nitrogen removal, and hydroxyapatite proved to be limited in the removal of heavy metals, highlighting the need for further studies.