Treatment of residual water from a slaughterhouse: Efficiency of the coagulation - flocculation process.

Abstract

The objective of the present work was to evaluate the benefits and efficacy of the coagulation and flocculation treatment of wastewater from a slaughterhouse. For this, 500 ml samples were analyzed and aluminum sulfate (1%) and ferric chloride (1%) were used as coagulating agents, cationic polymer (1%) as a flocculating agent and highspeed gradients (150 – 300 rpm) and low speed (37 – 75 rpm). The initial concentrations of pollutants in the effluent were: pH (6.98 – 6.97), turbidity (436 – 537 NTU), SST (430.6 – 228.8 ppm), dissolved oxygen (1.17 – 2.11 mg/L), nitrates (0 – 7.5 mg/L). The best results were obtained with the addition of 6 ml of aluminum sulfate; 1 ml of the cationic polymer, a mixing speed of 200 rpm and a sedimentation time of 25 mi nutes, which decreased the turbidity concentrations 4.85 NTU, dissolved oxygen 9.16 mg/L and STD 333. 6 ppm. Likewise, the addition of 2 mL of ferric chloride, 0.75 mL of the cationic polymer, a fast mixing speed of 300 rpm and a sedimentation time of 35 minutes, allowed to obtain as a result 15.46 NTU, dissolved oxygen 9.45 mg/L, STD 224.7 ppm, nitrates 6 mg/L.