Coagulant selection should depend on water temperature and raw water quality characteristics such as particle concentrations and types , and the concentration and nature of natural organic matter (NOM). The dosage range of coagulants depend on the type of coagulants and pH of the wastewater. You can learn from this article
Article Evaluation study of a slaughterhouse wastewater treatment pl...
Dissolved air floatation ( DAF ) and coagulation- floatation units, are widely used for the removal of total suspended solids ( TSS ), colloids and fats from slaughterhouse watercourses. Adding 100mg/L polyaluminium chloride ( PACI )and applied voltage of 40 V results in the removal of 99% of COD AND BOD5.......dose of alum as coagulant in abattoir wastewater treatment For details consult https//pdfs.semanticscholar.org
I have used Alum (Dose: 250 to 300 mg/L) and cationic polyelectrolyte (Dose 1 mg/L) for treating slaughterhouse wastewater. The results are promising. The other operating parameters of DAF in my case are as follows:
Hydraulic loading rate (Including recycle): 5.69 m³/m².hr; recycle pressure: 6.5 kg/cm², Percentage Recycling Ratio 33 %; Air to Solid ratio: 0.016 mL/gm.