ELIMINACIÓN DE MATERIA FOSFATADA PRESENTE EN AGUA RESIDUAL UTILIZANDO BIOCALCIO

Abstract

The physicochemical treatment (PT) of food industry wastewater was investigated. In the first stage, calcium magnesium acetate (CaMgAc4) was synthesized using eggshell (biocalcium), magnesium oxide and acetic acid in a 1:1:1 stoichiometric ratio. In the synthesis, the thermodynamic parameters (ΔH, ΔS and ΔG) indicated that the reaction was endothermic and spontaneous. The samples were characterized by infrared spectroscopy (IR), scanning electronic microscopy (SEM), X-ray diffraction (XRD) and electron X-ray dispersive spectroscopy (EDS). Subsequently, CaMgAc4 was used to precipitate the phosphate matter. IR analysis revealed that the main functional groups were representative of the acetate compounds and the presence of (OH-) groups and carbonates. In the physico-chemical treatment, a response surface design was used to determine the variables that influence the process (pH, time and concentration), and the response variable was phosphorus removal. The treatments were carried out in wastewater industry with an initial concentration of 658 mg/L TP. The optimal conditions of the precipitation treatment were pH 12, time 12 min, CaMgAc4 concentration of 13.18 mg/L, and TP removal efficiency of 100%, and carbonates, total nitrogen, sulfates, turbidity and color were also removed. These conditions allowed the total elimination (100%) of total phosphorus and phosphates. In addition, 81.43% BOD5 and 81.0% COD, 98.9% turbidity, 95.01% color, and 92% nitrogen matter were removed. These results indicated that it is possible to obtain a clean effluent industry that is substantially free of suspended matter and nutrients by chemical precipitation with CaMgAc4 synthesized from eggshell.