Distribution of organic matter forms and nitrogen in slaughterhouse wastewater

Abstract

This study addresses the characterization and fractionation of organic matter and nitrogen in effluents from the cattle slaughtering process, aiming to generate key information for optimizing their treatment. The methodology included the collection and physicochemical characterization of the effluents, followed by the fractionation of organic matter and nitrogen using sequencing batch reactors and applying Pearson correlations to the obtained results. High concentrations of COD (12,867 mg/L) and BOD₅,20 (5,282 mg/L) were identified, indicating moderate biodegradability. Likewise, total Kjeldahl nitrogen (TKN) reached 529 mg/L, and total phosphorus 13 mg/L, exceeding regulatory limits. The results showed that 21.2% of the COD corresponds to non-biodegradable fractions, and that inert and particulate organic nitrogen represents a significant proportion of the TKN, which limits the effectiveness of conventional biological treatments. It was concluded that, for efficient removal of the pollutant load, a combined treatment scheme is necessary. Pretreatment with dissolved air flotation (DAF) is recommended for the removal of solids and fats, followed by a biological process using sequencing batch reactors (SBR) for the elimination of biodegradable organic matter and nitrogen. Finally, coagulation-flocculation and activated carbon adsorption are proposed as complementary strategies for the removal of recalcitrant fractions. This integrated approach ensures compliance with environmental regulations and promotes sustainability in the meat processing industry.