Polyaluminium chloride, Al-2(SO4)(3) and Fe-2(SO4)(3) coagulants were added (up to 0.8% by vol.) to pig slurry filtrate to coagulate suspended org. mater, remove turbidity and color as well as decrease the chem. O-2 demand. The Al-contg. coagulants were more efficient than the Fe-contg. one. Use of lowest dose of Al-based coagulants (0.125% by vol.) resulted in a decrease in turbidity by 97%, decrease in chem. O-2 demand by 67.5% and decrease in color intensity by about 89%.