Removal of inorganic chemical species and organic matter from slaughterhouse wastewater via calcium acetate synthesized from eggshell.

The physicochemical treatment (PT) of slaughterhouse wastewater (SWW) was investigated. In the first stage, calcium acetate (Ca(Ac)) was synthesized in five different ways: (1) acetic acid (HAc) and chicken eggshell (CaAc1), (2) lime (CaAc2), (3) a 1:1 eggshell and lime mixture (CaAc3), (4) a 1:2 eggshell and lime mixture (CaAc4), and (5) calcium oxide via the calcination of eggshell (CaAc5). The synthesized Ca(Ac) samples were characterized by IR, SEM, XRD, and EDS. Subsequently, the samples were used to precipitate oxyanions and organic matter. The experiments were carried out at pH 4 and 12. For the treatment with CaAc1 at pH 4, an acid (HCl, HSO, or HAc) was also added. The best results for CaAc1 in acid media were attained with HCl, where removal efficiencies of 82.23% total suspended solids, 76% turbidity, 81.43% color, 53.86% Fe, 69.74% Cu, and 14.64% Na were observed. This treatment also removed ∼99% fecal and total coliforms, 26.49% COD, and 78.39% TOC. The experiments were also performed at pH 12 using CaAc1. These afforded removal efficiencies of 92.7% turbidity, 84.7% color, 40.5% phosphates (PO), and 64.7% sulfates (SO). In addition, this method removed metals, 35.37% COD and 99% fecal and total coliforms.