Studies were conducted to evaluate potential applications of collagen dispersions in liquid-solid separation processes for water treatment and sludge dewatering. The collagen dispersion was prepared from fibrillar type I bovine hide buffered with organic acid. The results indicate that the collagen dispersion was effective as a coagulant for removing turbidity caused by colloidal clay particles and as a sludge conditioner for thickening and dewatering sludge from a water treatment plant. Coagulation of kaolin suspensions using the collagen reduced the initial turbidity of the suspension by 92%. Additions of collagen to sludge from a water treatment plant improved the settling rate during gravity thickening by a factor of five and improved the specific cake resistance of the sludge during filtration by a factor of three. Research is continuing on the mechanisms and kinetics of collagen dispersions in coagulation and sludge dewatering.